Sources of and genetic action of resistance in barley to different virulence types of Pyrenophora teres,
the causal organism of net blotch
by Michael Eidis Bjarko
A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE
in Plant Pathology
Montana State University
© Copyright by Michael Eidis Bjarko (1979)
Abstract:
Research was initiated in February, 1977 to study the reactions of different barley lines to isolates of
Pyrenophora teres.
Studies revealed that maximum sporulation of P. teres in culture could be obtained using V8 juice as a
growth medium while incubating the cultures under an eight hour photoperiod of 17-18° C.
Twenty-six isolates of P. teres, fifteen from the Middle East and eleven from Montana, were separated
into different virulence types based on the differential reactions of different barley lines. Seven distinct
Middle East virulence types and five Montana virulence types could be distinguished.
Nine of these virulence types were used to screen 147 barley lines for resistance to P. teres. Nine lines
were found to contain resistance to all nine virulence types. These lines were C.I. 1615, C.I. 4207, C.I.
5298, C.I. 5401, C.I. 5845, C.I. 7208, C.I. 9768, C.I. 13262 and Unitan. An additional twenty-two lines
were found to contain resistance to eight of the nine virulence types of P. teres.
Crosses involving resistant and susceptible barley lines were made, and the resulting F2 populations
were tested with different isolates of P. teres. It was found that at least five major genes exist in barley
for resistance to P. teres. Four lines, C.I. 5791, C.I. 9819, Unitan and Steptoe each contain at least three
genes for resistance.
Evidence for additive resistance to P. teres was found. Crosses between susceptible parents produced
F2 seedlings which were more resistant than either parent to the isolate of P. teres used in the test. STATEMENT OF PERMISSION TO COPY
In p r e s e n tin g t h i s t h e s i s in p a r t i a l f u lf il lm e n t o f th e
r e q u i r e m e n ts f o r an a d v a n c e d d e g r e e a t M ontana S t a t e U n i v e r s i t y , ,
I a g r e e t h a t t h e L i b r a r y s h a l l make i t
in s p e c tio n .
fre e ly a v a ila b le fo r
I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y in g
o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may b e g r a n t e d b y my m a io r
p r o f e s s o r , o r , i n h i s a b s e n c e , by t h e D i r e c t o r o f L i b r a r i e s .
i s u n d e r s to o d t h a t a n y c o p y in g o f p u b l i c a t i o n o f t h i s t h e s i s
f o r f i n a n c i a l g a in s h a l l n o t b e a llo w e d w ith o u t my w r i t t e n
p e rm is s io n .
S i g n a tu r e
D a te
Z, /9
7?
It
SOURCES OF AND GENETIC ACTION OF RESISTANCE IN BARLEY
TO DIFFERENT VIRULENCE TYPES OF
VyHdnophotia. toJiHA,
THE CAUSAL ORGANISM OF NET BLOTCH
b
y
•
M ic h a e l E i d i s B ja rk o
A t h e s i s s u b m itte d i n p a r t i a l f u l f i l l m e n t
o f t h e r e q u i r e m e n ts f o r t h e d e g re e
of
MASTER. OF SCIENCE
■
i.
P l a n t P a th o lo g y
A p p ro v ed :
C h a i r p e r s o n , G ra d u a te C oigm ittee
H ead, M ajo r D e p a rtm e n t
G ra d u a te Demn
MONTANA STATE UNIVERSITY
B ozem an, M ontana
M arch , 1979
Iii
ACKNOWLEDGMENT
I e x p r e s s my d e e p e s t a p p r e c i a t i o n and t h a n k s t o t h e f o llo w in g
p e o p le :
' D r. E .L . S h a rp f o r h i s s u p p o r t , e n c o u ra g e m e n t, an d g u id a n c e w h ile
s e r v i n g a s my. m a jo r p r o f e s s o r .
D r. T.W. C a r r o l l , D r. D .E . M a th re an d P r o f e s s o r R .F . E s l i c k f o r
t h e i r h e lp and a d v ic e w h i l e s e r v i n g on my g r a d u a t e c o m m itte e .
D r. H .E . B ockelm an f o r h i s p a t i e n c e , a d v ic e a n d e n c o u ra g e m e n t
th r o u g h o u t my g r a d u a t e c a r e e r .
My f e l l o w g r a d u a t e ' s t u d e n t s f o r t h e i r u n d e r s t a n d in g and s u p n o r t .
My p a r e n t s , A l b e r t a n d M a ria n , and my s i s t e r s , Ann, Mary J o ,
A l l i s o n and M e l i s s a , w hose c o n s t a n t lo v e an d e n c o u ra g e m e n t m eant so
m uch.
US-AID f o r f i n a n c i a l s u p p o r t .
TABLE OF CONTENTS
V ita
.....................................................
ii
A c k n o w le d g m e n t.........................................................
ill
T a b le o f C o n te n ts . . . ...........................................................................................................i v
L i s t o f T a b l e s ....................................................................................................................................
A b s t r a c t ..........................................................................................................
In tro d u c tio n
. . . . . . .
vi
. . .............................................................................................................................. I
L i t e r a t u r e R e v i e w ....................................................
C h a p te r I :
2
The E f f e c t o f D i f f e r e n t G row th M edia on t h e
S p o r u l a t i o n o f Vyunnophofia. teAQA ..........................
16
M a t e r i a l s an d M e t h o d s ................................................ ■. . .. ............................ ....
. 16
R e s u l t s a n d D i s c u s s i o n ...........................................
.1 7
C h a p te r 2:
E f f e c t o f P h o to p e r io d a n d Type o f G row th
Medium on t h e S p o r u l a t i o n o f P.
M a t e r i a l s a n d M ethods .....................................................
. . .................................. 20
R e s u l t s a n d D i s c u s s i o n .....................................................................
C h a p te r 3 :
20
.2 1
D e t e r m in a t io n o f D i f f e r e n t V i r u le n c e T ypes o f
Vytimophono, t & i t e .....................................................................
28
M a t e r i a l s a n d M e t h o d s ............................
28
R e s u lts and D is c u s s io n
30
C h a p te r 4 :
............................................
S c r e e n in g o f B a r le y L in e s f o r R e s i s t a n c e t o
Vytimopkoha tutizA ............................................................. ; .
39
M a t e r i a l s and M e t h o d s ............................................................................... ’ ..................39
R e s u l t s and D is c u s s i o n
40
V
T a b le o f C o n te n ts ( c o n t , )
C h a p te r 5 :
T e s tin g o f F- P o p u la tio n s f o r R e s is ta n c e to
D i f f e r e n t I s o l a t e s o f Vyh-dnophoha. t& illA .........................
M a t e r i a l s an d M ethods ........................................................................
R e s u lts
. . . . . . .
a n d D i s c u s s i o n .......................
54
54
56
D i s c u s s i o n ..........................................................................................................................................82
R e f e r e n c e s C i t e d ........................................................................ ....
. . ........................ ....
91
A p p e n d i x ....................................................................... .... ............................................................. 96
vi
LIST OF TABLES
•
T able.
1 - 1: D i f f e r e n t i a l s p o r u l a t i o n ( s p o r e s /m l) o f P. teAZA on e i g h t
t y p e s o f g ro w th m e d i a .................................. ..............................................................ig
2-
1 : S p o r u l a t i o n ( s p o r e s / m l ) o f P.
on d i f f e r e n t a g a r ty p e s
a t d i f f e r e n t p h o t o p e r i o d s . . . .................................. ■ ......................
24
2 -2 :
A v e ra g e s p o r u l a t i o n ( s p o r e s /m l) o f P. £2/l&> a t e a c h p h o to ­
p e r i o d ........................................................................ ....................... ............................ . 2 7
2 -3 :
A v e ra g e s p o r u l a t i o n ( s p o r e s /m l) o f P.
t y p e ......................................
£ qAQA> on e a c h a g a r
27
2-
4 : A n a ly s is ' o f v a r i a n c e t e s t .......................................................................................27
3-
1 : I s o l a t e s o f P.. £.2AZA in c l u d e d i n t h e c o l l e c t i o n and t h e
p l a c e o f o r i g i n o f e a c h ........................ .... . .................................................. 33
3 -2 :
V a r i e t i e s a n d C . I . l i n e s u s e d i n d e te r m i n in g t h e d i f f e r e n t
v i r u l e n c e t y p e s o f P. £eJL2A . ................................................
3 -3 :
V i r u le n c e t y p e s
o f th e M id d le E a s t i s o l a t e s o f P.
3 -4 :
V ir u le n c e t y p e s
o f t h e M ontana i s o l a t e s o f P.
3 -5 :
toAU .. . .
Key f o r i d e n t i f y i n g t h e v i r u l e n c e t y p e s o f t h e M id d le
E a s t e r n i s o l a t e s • ; ........................................... ' . ............................. . . . .
1 :.
4 -2 :
4 -3 :
35
tOAQA........................... 36
3 - 6 : Key f o r i d e n t i f y i n g t h e v i r u l e n c e t y p e s o f t h e M ontana
i s o l a t e s ' ......................
4-
34
R e la tiv e r e s is ta n c e , o f v a rio u s b a rle y l in e s to d i f f e r e n t
i s o l a t e s o f VyHmopkoKa toKOM ........................................
R e l a t i v e r e s i s t a n c e . o f b a r l e y l i n e s to v a r i o u s i s o l a t e s
• o f Vyh-tnopkotia. tOAQA ( r e s i s t a n t an d i n t e r m e d i a t e r e a c t i o n s
c o m b i n e d ) .................................................................................
37
38
.43
49
R e l a t i v e r e s i s t a n c e o f b a r l e y l i n e s <to n e t b l o t c h , i n
■ r e l a t i o n t o p r e v i o u s s c r e e n i n g t e s t s ........................ .. .............................. 52
v ii
L i s t o f T a b le s ( c o n t . )
T a b le
4-
4 : R e la tiv e r e s i s t a n c e o f b a r le y l i n e s to n e t b lo tc h , in r e l a ­
t i o n to p r e v i o u s s c r e e n i n g t e s t s ( r e s i s t a n t an d i n t e r m e d i a t e
r e a c t i o n s c o m b i n e d ) ........................ .... . .................................. ..........................53
5-
1 : R e a c ti o n s o f F„ p o p u l a t i o n s t e s t e d to d i f f e r e n t i s o l a t e s
o f P. t&i&A . 7 ................................................ .................................................... ..
69
5 -2 :
B a r le y l i n e s , w i t h p o s s i b l e genes, i n c o m m o n ........................................... 79
5 -3 :
P o s s i b l e n u m b ers o f g e n e s f o r r e s i s t a n c e i n e a c h l i n e
5 -4 :
E f f e c t o f s u s c e p tib le p a r e n ts o f e x p re s s io n o f r e s i s t a n c e
5 -5
E v id e n c e f o r a d d i t i v e r e s i s t a n c e t o P.
................. 80
. . .8 0
t<2/LQJ> ........................................81
v iii
ABSTRACT
"R esearch was i n i t i a t e d i n F e b r u a r y , 1977 t o s t u d y th e r e a c t i o n s
o f d i f f e r e n t b a r l e y l i n e s t o i s o l a t e s o f Vy>iQ,nopho>iCL tOA&t,.
S t u d ie s r e v e a l e d t h a t maximum s p o r u l a t i o n o f P. £eA<Lt> i n c u l ­
t u r e c o u ld b e o b t a i n e d u s i n g V8 j u i c e a s a g ro w th m edium w h ile i n c u ­
b a t i n g t h e c u l t u r e s u n d e r a n e i g h t h o u r p h o t o p e r io d o f 1 7 -1 8 ° C..
T w e n ty - s ix i s o l a t e s o f P. £oAZt>f f i f t e e n from th e M id d le E a s t and
e le v e n fro m M o n ta n a , w e re s e p a r a t e d i n t o d i f f e r e n t v i r u l e n c e t y p e s
b a s e d on t h e d i f f e r e n t i a l r e a c t i o n s o f d i f f e r e n t b a r l e y l i n e s .
Seven
d i s t i n c t M id d le E a s t v i r u l e n c e t y p e s a n d f i v e M ontana v i r u l e n c e t y p e s
c o u ld b e d i s t i n g u i s h e d .
N in e o f t h e s e v i r u l e n c e t y p e s w e re u s e d t o s c r e e n 147 b a r l e y l i n e s
f o r r e s i s t a n c e t o P. £.2A<LA>. N in e l i n e s w e re fo u n d t o c o n t a i n r e s i s ­
ta n c e to a l l n in e v ir u le n c e ty p e s .
T h e s e l i n e s w e re C . I . 1 6 15, C .I .
4 2 0 7 , C . I . 5 2 9 8 , C . I . 5 4 0 1 , C . I . 5 8 4 5 , C . I . 7 2 0 8 , C . I . 9 7 6 8 , C .I . 13262
and U n ita n .
An a d d i t i o n a l tw e n ty -tw o l i n e s w e re fo u n d t o c o n t a i n r e ­
s i s t a n c e t o e i g h t o f t h e n i n e v i r u l e n c e t y p e s o f P. t&iQA.
C r o s s e s i n v o l v i n g r e s i s t a n t a n d s u s c e p t i b l e b a r l e y l i n e s , were,
m ade, a n d t h e r e s u l t i n g F^ p o p u l a t i o n s w e re t e s t e d w i t h d i f f e r e n t
i s o l a t e s o f P.
.
I t was fo u n d t h a t a t l e a s t f i v e m a jo r g e n e s
e x i s t i n b a r l e y f o r r e s i s t a n c e t o P. teAZA. F o u r l i n e s , C . I . 5 7 9 1 ,
C . I . 9 8 1 9 , U n ita n an d S t e p to e e a c h c o n t a i n a t l e a s t t h r e e g e n e s f o r
re s is ta n c e .
E v id e n c e f o r a d d i t i v e r e s i s t a n c e t o P. t-QA-ZA w as f o u n d . C r o s s e s
b e tw e e n s u s c e p t i b l e p a r e n t s p ro d u c e d F^ s e e d l i n g s w h ic h w e re m ore r e ­
s i s t a n t t h a n e i t h e r p a r e n t t o t h e i s o l a t e o f P. tztiZA u s e d i n t h e t e s t .
INTRODUCTION
. N et b l o t c h o f b a r l e y , c a u s e d by
common on a l l c o m m e rc ia l v a r i e t i e s .
PyfninophoAa. £ qA qJ>, I s a d i s e a s e
I t i s fo u n d w h e re v e r b a r l e y i s
.grown, a n d i s e s p e c i a l l y s e v e r e u n d e r c o o l , hum id c o n d i t i o n s .
C hanges i n c u l t u r a l p r a c t i c e s , s u c h a s t h e e x t e n s i v e u s e o f i r r i ­
g a t i o n , minimum t i l l a g e , c o n tin u o u s c r o p p in g and e a r l y so w in g o f b a r ­
l e y , and r e s t r i c t i o n s on c h e m ic a l t r e a t m e n t , e s p e c i a l l y t h e m e rc u ry
s e e d t r e a t m e n t s , h a v e p r o d u c e d a n e n v iro n m e n t c o n d u c iv e t o th e g ro w th
an d s p r e a d o f t h i s o r g a n is m .
The so w in g o f s u s c e p t i b l e b a r l e y v a r i ­
e t i e s t h e n p r o v id e s a p o t e n t i a l f o r s e v e r e d i s e a s e e p id e m ic .
N et b l o t c h , a lo n g w i t h b a r l e y s c a l d
(Rh.yric.OApo^ cu m Ae.caLL&) , h a s
p ro d u c e d d e t r i m e n t a l e f f e c t s on t h e y i e l d and m a l t i n g q u a l i t y o f b a r l e y
grow n on t h e F a i r f i e l d Bench i n N o r t h c e n t r a l M o n tan a, w h ere y i e l d 1
l o s s e s i n 1973 w ere e s t i m a t e d t o b e a s h i g h a s 50% i n some f i e l d s .
D u rin g t h e 1 9 7 7 -7 8 g ro w in g s e a s o n i n C a l i f o r n i a , i n f e c t i o n by
P. te A d A
was so s e v e r e t h a t f i e l d s w ere b u rn e d r a t h e r th a n h a r v e s t e d .
T h is s tu d y was i n i t i a t e d
r e s i s t a n c e t o P.
of
£.2A.(IA.
i n o r d e r t o f i n d and e v a l u a t e s o u r c e s o f
A ls o , th e r e l a t i o n s h i p o f d i f f e r e n t i s o l a t e s
P. teAZA t o d i f f e r e n t s o u r c e s o f r e s i s t a n c e , a n d t h e g e n e t i c s o f
r e s is ta n c e to
P. toA-ZA was s t u d i e d .
LITERATURE. REVIEW
Vy>iQ.nophoH.a. tQAQA D r e c h s . i s t h e c a u s a l o rg a n is m o f n e t b l o t c h o f
b a rle y .
The i m p e r f e c t s t a g e o f t h i s
S a c c ., s y n .
fu n g u s,
Holm^intho^potUum tQAQA
VtiQ.Q.lnAZQAtX. £ oA.QA I t o . , i s p l a c e d i n t h e c l a s s H y p h o m y c e te s,
b a s e d on t h e f a c t t h a t t h e c o n i d i a a r e n o t b o rn e i n a n y form o f p y c n id ium o r a c e r v u l u s
( T a l b o t , 1 9 7 1 ). . The p ig m e n ta t io n o f t h e m ucelium an d
c o n i d i a p l a c e i t i n t h e f a m i ly D em ati a c e a e .
The g e n u s
HoImlnttko^potUum
i s r e c o g n i z e d c h i e f l y by t h e p r e s e n c e o f bro w n , s e p t a t e c o n id i o p h o r e s
an d l a r g e , b ro w n , p h ra g m o id c o n i d i a
( T a l b o t , 1 9 7 2 ).
The b in o m ia l HeZ-
minthoApotiium i-OAOM was f i r s t a p p l i e d by S a c c a rd o t o a fu n g u s c o l l e c t e d
on l e a v e s o f b a r l e y i n 1881 ( D r e c h s l e r , 1 9 2 3 ).
a s h a v in g 3 - s e p t a t e c o n d io p h o r e s a r i s i n g
The fu n g u s was d e s c r i b e d
i n a g ro u p o f f i v e from a
g r e e n s u b s tr a tu m an d b e a r i n g a t t h e t i p a s i n g l e c o n id iu m .
The c o n i d i a
w e re d e s c r i b e d a s d a r k g r e e n s t r u c t u r e s , t h i c k w a l l e d , 4 - 5 s e p t a t e ,
e l l i p s o i d a l o r s u b c y l i n d r i c a l and t a p e r i n g p e r c e p t i b l y to w a rd t h e
ro u n d e d e n d s .
The o r i g i n a l g e n u s
B e c a u se o f t h i s ,
Ho£imA.ntthoApotu.lM was e x tr e m e ly h e te r o g e n e o u s . ■
g ro u p s o f s p e c i e s h a v e b e e n s e g r e g a t e d from i t and
p l a c e d i n t o m ore d i s c r i m i n a t i n g g e n e r a .
p l a c e d by I t o i n t h e g e n u s
The n e t b l o t c h o rg a n is m was
VtvtahiZQAOL,- b a s e d p r i m a r i l y on t h e o r i g i n ,
d e v e lo p m e n t and m o rp h o lo g y o f t h e c o n d io p h o r e s a n d c o n i d i a
1962; T a lb o t, 1 9 7 3 ).
(S c h o e m a k e r,
VAQ.chiZQACL d i f f e r s from HoZmZntkoipotuiLm i n t h a t ,
t h e c o n i d i a d e v e lo p a t t h e t i p s o f s u c c e s s i v e l a t e r a l p r o l i f e r a t i o n s
-3 -
o f t h e .c o n id i o p h o r e s a n d a r e p s e u d o p le u r o g e n o u s .
c y l i n d r i c a l , a n d s u b h y a li n e t o p a l e .b ro w n .
They a r e phragm oid*
C o n i d i a l g e rm tu b e s a r e
l a t e r a l , u s u a l l y a m p h ig e n o u s , a n d may a r i s e from i n t e r c a l a r y a s w e l l
a s te rm in a l, c e l l s
( L u t t r e l l , 1 9 7 7 ; T a l b o t , 1973;. S c h o e m a k e r, 1 9 6 2 )..
The c o n i d i o p h o r e s o f
o f tw o to. t h r e e .
PysuLnophosia teA(L6 o c c u r s i n g l y o r i n g ro u p s
They a r e s t r a i g h t t o f l e x o u s , o f t e n s w o lle n a t t h e
b a s e an d a r e p a l e t o m id -b ro w n o r o l i v a c e o u s i n c o l o r .
1 2 0 -2 0 0 x 7 -1 1 pm.
They m e a s u re
The c o n i d i a a r e s t r a i g h t , c y l i n d r i c a l , w ith ro u n d e d
a p i c a l c e l l s an d c o n s t r i c t e d s e p t a .
d u c in g a s u b g lo b o s e a p p e a r a n c e .
The b a s a l c e l l i s i n f l a t e d , p r o ­
.T h e c o n i d i a a r e 1 -1 1 s e p t a t e , 3 0 -1 7 5
x 1 5 -2 3 pm and s u b h y a li n e to g r e e n f u l i g e n o u s i n c o l o r .
s e s s i l e and g e r m in a te fro m a n y o r a l l c e l l s
They a r e
(D r e c h s le r , 1923; L u t t r e l l ,
1 9 5 1 ; E l l i s , 1 9 7 1 ) . . Among t h e P y re n o p h o ra s p e c i e s , t h e i n f l a t e d b asalc e l l . and c o n s t r i c t e d s e p t a a r e u n iq u e t o
P.
The p e r f e c t , o r s e x u a l , s t a g e o f t h i s o rg a n is m p r o d u c e s a s c i
an d a s c o s p o r e s , p l a c i n g i t i n t h e s u b d i v i s i o n ' A sco m y co ti n a .
The a s c i
a r e b i t u n i c a t e , p l a c i n g i t i n t h e c l a s s L o c u lo a s c o m y c e te s and t h e
p re se n c e o f p se u d o p ara p h y ses p la c e s i t
b o t , 1 9 7 1 ).
in th e o rd e r P le o s p o r a le s
( T a l­
D r e c h s l e r (1 9 2 3 ) w as t h e f i r s t t o d e s c r i b e t h e a s c i -
g e ro u s s ta g e o f
VytlZYlophoKOL
He p la c e d i t i n t h e g e n u s
Vytvino-
phoKCL, b a s e d on t h e p r e s e n c e o f s e t a e on t h e p e r i t h e c l a l s u r f a c e .
■The a s c i o f
P. t&MUt a r e c lu b .s h a p e d o r s u b c y l i n d r i c a l , ro u n d e d
a t t h e a p e x an d w i t h a s h o r t s t a l k a t t h e b a s e .
They a r e b i t u n i c a t e .
-4 -
an d 1 8 0 -2 7 4 x 3 0 -6 1 ym.
The a s c o s p o r e s a r e l i g h t b ro w n , 1 8 -2 8 x 4 3 -6 1 ym,
e l l i p s o i d a l , w i t h t h r e e t r a n s v e r s e s e p t a a n d one o r tw o l o n g i t u d i n a l
s e p t a i n t h e m e d ia n c e l l s , b u t n o t i n t h e . t e r m i n a l c e l l s .
The s p o r e s
a r e much c o n s t r i c t e d a t t h e s e p t a , w i t h g e rm tu b e s f o rm in g from a n y o r
a ll c e lls
( D r e c h s l e r , 1 9 2 3 ; S m e d e g a r d - P e te r s e n , 1 9 7 2 ) . ■
Pysi&yiophoSLCL teASA a l s o p r o d u c e s p y c n id i a on h o s t t i s s u e and i n
c u ltu re .
They a r e g lo b o s e t o p e a r - s h a p e d , 6 4 -1 7 2 ym i n d i a m e te r , w i t h
a t h i n f r a g i l e w a ll.
age.
They a r e y e llo w t o brow n i n c o l o r , d e p e n d in g on
The s p o r e s a r e h y a l i n e , s p h e r i c a l o r e l l i p s o i d a l , n o n - s e p t a t e
an d I . 0 - 1 .9 x I . 4 - 3 .2 ym ( S m e d e g a r d -P e te r s e n , 1 9 7 2 ) .
The f u n c t i o n
o f t h e s e p y c n id i o s p o r e s i s n o t know n, a lt h o u g h i t i s th o u g h t th e y may
a c t a s s p e r m a ti a (M cD onald, 1 9 6 3 ; S m e d e g a r d -P e te r s e n , 1 9 7 2 ).
The h e t e r o t h a l l i c n a t u r e o f
1 9 6 3 ; S m e d e g a r d - P e te r s e n , 1 9 7 2 ).
P. •toAU h a s b e e n shown (M cD onald,
M o n o c o n id ia l o r m o n o a s c o s p o ric i s o ­
l a t e s d i d n o t p ro d u c e f e r t i l e p e r i t h e c i a when p a i r e d w i t h o t h e r t h a n
t h e i r o p p o s i t e m a tin g t y p e s .
M a tu re p e r i t h e c i a o f P.
tQAQJ* w ere p r o ­
d u c e d by g ro w in g m ix ed s u s p e n s io n s o f two c o m p a tib le s i n g l e - s p o r e
is o la te s .
A 1 :1 r a t i o o f t h e m a tin g t y p e s w as o b ta in e d .w h e n a s c o -
s p o r e p ro g e n y fro m p e r i t h e c i a w e re b a c k c r o s s e d t o p a r e n t a l i s o l a t e s
(M cD onald, 1 9 6 3 ).
P. teAZA. p r o d u c e s t h r e e t y p e s o f s p o r e s ; a s c o s p o r e s , c o n i d i a and
p y c n id io s p o re s .
The a s c o s p o r e s an d c o n i d i a w i l l r e a d i l y i n f e c t s u s ­
c e p tib le h o st tis s u e .
S u s p e n s io n s o f p y c n id i o s p o r e s h a v e n e v e r
-5 -
p ro d u c e d sym ptom s ( S m e d e g a r d -P e te r s e n , 1 9 7 2 ).
A ll t h r e e sp o re ty p e s
w i l l g e r m in a te an d grow on a r t i f i c i a l m e d ia , a lt h o u g h t h e g ro w th o f
p y c n i d i o s p o r e s i s i n i t i a l l y v e r y s lo w .
Once m y c e liu m h a s b e e n e s t a b ­
l i s h e d , g ro w th o f c u l t u r e s fro m p y c n id i o s p o r e s i s n o r m a l.
S u s p e n s io n s
o f.h o m o g e n iz e d m y celiu m from c u l t u r e s o r i g i n a t i n g from a n y o f t h e
th r e e sp o re ty p e s w i l l r e a d i ly i n f e c t b a r le y l e a f t i s s u e .
C o n id ib -
p h o r e s a n d c o n i d i a a r e p ro d u c e d fro m t h e sy m p to m a tic t i s s u e .
.
The fu n g u s o v e r w i n t e r s a s m y celiu m i n i n f e s t e d p l a n t d e b r i s and
in fe c te d seed .
I t a l s o o v e r w i n t e r s a s p e f i t h e c i a on i n f e s t e d s tr a w .
A lth o u g h s e e d l i n g i n f e c t i o n r e s u l t i n g from s e e d i s known to o c c u r
t h e e x t e n t t o w h ic h t h i s h a p p e n s i s unknown and a p p e a r s to be a f f e c t e d
v e r y m u c h 'b y t h e e n v ir o n m e n t.
I n D enm ark, S m e d e g a r d -P e te rs e n (1 9 7 4 )
fo u n d 18.5% a n d 13.8% o f t h e s e e d l i n g s o f t h e s u s c e p t i b l e b a r l e y
c u l t i v a r s Wing a n d L a u d a , r e s p e c t i v e l y , show ing sym ptom s due to
in fe c te d seed .
P i e n in g
( 1 9 6 8 ) , i n C an ad a, fo u n d o n ly 0.5% t o 1.5%
o f b a r l e y s e e d l i n g s show ing symptom s r e s u l t i n g from s e e d i n f e c t i o n .
S e e d lin g i n f e c t i o n fro m i n f e c t e d s e e d o c c u r s a t 1 0 -1 5 ° C, b u t n o t
a b o v e 20° C ( D r e c h s l e r , 1 9 2 3 ).
L e s io n s may d e v e lo p o n t h e c o l e o p t i l e
a s a r e s u l t o f i n f e c t e d s e e d , b u t morfe o f t e n i t i s t h e f i r s t , o r
p l u m u l a r , l e a f w h ic h i s a t t a c k e d .
K e n n e th ( i n S h i p to n , e t a l . , 1 973)
h as o b se rv e d t h a t i n f e c ti o n o f th e h u l l i s in c o n s e q u e n tia l.
For
s e e d l i n g i n f e c t i o n t o o c c u r t h e c a r y o p s i s i t s e l f m u st b e i n f e c t e d .
Even w i t h low p e r c e n t a g e s
( 0 .5 -1 .5 % ) o f t h e p l a n t s i n f e c t e d
—6—
v i a s e e d - b o r n e in o c u lu m , P i e n in g (1 9 6 8 ) o b s e rv e d t h a t w h ere l e a v e s
w ith p r im a r y i n f e c t i o n w e re n o t re m o v e d , tw ic e a s many p l a n t s w ere
i n f e c t e d t w e n t y - e i g h t d a y s a f t e r e m e rg en c e a s on p l o t s w h ere i n f e c t e d
l e a v e s w e re rem oved a s s o o n a s t h e y w e re n o t i c e d .
I t th e re fo re ap­
p e a r s t h a t t h e c h i e f d a n g e r o f s e e d - b o r n e in o c u lu m i s i n p r o v id i n g
a p o t e n t i a l f o r d i s e a s e s p r e a d th r o u g h o u t th e g ro w in g s e a s o n and t h e
u l t i m a t e p r o d u c t i o n o f c o n ta m in a te d p l a n t d e b r i s w h ic h c o u ld p r o v id e
.
:
•
a b u n d a n t in o c u lu m t h e f o ll o w i n g y e a r .
. I n f e c t e d s tr a w i s o f m a jo r im p o r ta n c e a s a s o u r c e o f p r im a ry i n o c ­
ulum .
P ie n in g
(1968) o b s e r v e d 42% o f t h e p l a n t s i n f e c t e d w ith P.
tdAZA i n a f i e l d w h e re t h e p r e v i o u s y e a r t h e s tr a w a n d s t u b b l e w ere
l i g h t l y d i s c e d , w h e re a s o n ly 8% o f t h e p l a n t s w ere i n f e c t e d i n a
f i e l d w h e re t h e s tr a w and s t u b b l e w e re p lo u g h e d u n d e r d u r in g t h e
p re v io u s y e a r.
E a r ly i n t h e g ro w in g s e a s o n , when e n v ir o n m e n ta l c o n d i t i o n s a r e
f a v o r a b l e , c o n i d i a a r e p ro d u c e d on i n f e s t e d p l a n t d e b r i s .
p e r i t h e c i a r e l e a s e a s c i and a s c o s p o re s .
In a d d itio n ,
The p e r i t h e c i a a r e a l s o o f t e n
d e n s e l y c o v e re d w i t h c o n i d i a w h ic h form on t h e t i p s . o f s e t a e an d c o n id i o p h o r e s b e tw e e n t h e s e t a e .
The r e l a t i v e im p o r ta n c e o f t h e s p o re
t y p e s a s p r im a r y in o c u lu m i s unknown a n d a p p e a r s t o v a r y w ith g eo ­
g r a p h i c l o c a t i o n a n d e n v iro n m e n t ( S h ip t o n , 1 9 6 6 ; S m e d e g a r d - P e te r s e n ,
1 9 7 2 ; S h i p to n , e t a l . , 1 973; P i e n i n g , 1 9 6 8 ).
The c o n i d i a ' and a s c o s p o r e s w i l l b o th g e r m in a te r e a d i l y on h o s t
—
tis s u e .
7—
The g e rm tu b e s g iv e r i s e t o a p p r e s s o r i a - l i k e s t r u c t u r e s , and
i n f e c t i o n may o c c u r a f t e r a m o is t p e r i o d o f a s few a s f i v e h o u r s , a l ­
th o u g h 1 0 -3 0 h o u r s o f m o is t u r e a p p e a r s n e c e s s a r y f o r maximum i n f e c t i o n
( S h ip t o n , e t a l . , 1 9 7 3 ) .
The p e n e t r a t i o n h y p h ae p a s s th r o u g h th e
e p id e r m a l c e l l s a n d e n l a r g e s l i g h t l y upon p a s s i n g th r o u g h t h e in n e r
c e l l w a ll.
D ev elo p m en t o f t h e h y p h a e i s t h e n i n t e r c e l l u l a r , w ith
c e l l d e a th o c c u r r i n g i n a d v a n c e o f t h e f u n g u s .
The r e s p i r a t i o n r a t e
o f s u s c e p t i b l e b a r l e y l e a v e s i n c r e a s e s , s i g n i f i c a n t l y e x c e e d in g t h a t
o f n o n -in fe c te d le a v e s a f t e r s ix te e n h o u rs.
The r e s p i r a t i o n r a t e
c o n t i n u e s t o i n c r e a s e , r e a c h i n g a maximum r a t e c o i n c i d i n g w ith t h e
a p p e a r a n c e o f v i s i b l e n e c r o s i s , a f t e r w h ic h t h e r a t e s h a r p l y d e c r e a s e s .
E x t e r n a l l y , symptom s may b e e v i d e n t w i t h i n two d a y s o f i n f e c t i o n
( S h ip t o n , e t a l . , 1 9 7 3 ; S m e d e g a r d - P e te r s e n , 1 9 7 6 , 1 9 7 7 b ) .
C o n id io p h o re s a r i s e d i r e c t l y fro m b e tw e e n e p id e r m a l c e l l s o r
s to m a ta and p ro d u c e c o n i d i a on t h e s u r f a c e o f p r im a r y l e s i o n s .
T h e se
c o n i d i a t h e n c a u s e s e c o n d a r y i n f e c t i o n o f t h e d e v e lo n in g f o l i a g e .
T h is p r o c e s s i s r e p e a t e d th r o u g h o u t t h e g ro w in g s e a s o n , a s lo n g a s
c o n d i t i o n s r e m a in f a v o r a b l e .
C o m p lete n e c r o s i s o f t h e l e a v e s may
o c c u r by f l o w e r i n g tim e ( S c h a l l e r , 1 9 5 5 ; S h ip to n , e t a l . , 1 9 7 3 ).
Symptoms in d u c e d by P.
teA U o c c u r on t h e b l a d e s a n d s h e a t h s o f
t h e l e a v e s a n d may e x te n d t o t h e f lo w e r s a n d g r a i n s .
The i n i t i a l
l e s i o n s a p p e a r a s m in u te s p o t s o r s t r e a k s w h ic h i n c r e a s e i n s i z e t o
fo rm n a rr o w , d a r k b ro w n , l o n g i t u d i n a l a n d t r a n s v e r s e s t r e a k s .
—8 —
p r o d u c in g a n e t - l i k e p a t t e r n .
te ris tic of
P.
T h is n e t t i n g a p p e a r a n c e i s c h a r a c ­
and i t i s from t h i s a p p e a r a n c e t h a t t h e d i s ­
e a s e g e t s i t s common name o f n e t b l o t c h ( D r e c h s l e r , 1 9 2 3 ; D ic k s o n ,
1 9 5 6 ).
Is o la te s of
P. teA U h a v e b e e n c o l l e c t e d w h ic h do n o t p ro d u c e
t h e c h a r a c t e r i s t i c n e t t i n g sym ptom s on h o s t t i s s u e , b u t i n s t e a d p r o ­
d u c e s p o t l e s i o n s v e r y s i m i l a r t o t h o s e p ro d u c e d by
japonicum.
P.
T h e se i s o l a t e s w ere c o n s i d e r e d t o b e
Pl/AenophoAa
P. t2AeA r a t h e r t h a n
j CLponiam b e c a u s e t h e y c o u ld b e c r o s s e d w i t h i s o l a t e s o f P.
t h a t p ro d u c e t h e n e t t i n g sym ptom s (M cD onald, 1 9 6 7 ) .
P e te rs e n
form a
(1 9 7 1 ) s u g g e s t e d t h e d e s i g n a t i o n
S m edegard-
PyA2.nophoAa. £2A<LA> D r e c h s .
mcLCuZcuta fo rm a n o v a f o r t h e s p o t ty p e o f P. £2Ji2A, an d VyAnno-
phoAa tQA<l6 D r e c h s . fo rm a teAni f o r t h e n e t t y p e .
The symptom s in d u c e d by t h e s p o t form o f
P. teAZA a l s o o c c u r on
t h e b l a d e s and s h e a t h s o f t h e l e a v e s an d c o n s i s t o f d a r k brow n, e l l i p ­
t i c a l o r f u s i f o r m l e s i o n s m e a s u rin g up to 3 x 6 mm i n s i z e and s u r ­
ro u n d e d by a c h l o r o t i c z o n e o f v a r y i n g w id th ( S m e d e g a r d -P e te r s e n , 1971)
The s p o t form o f
P. tzAQJi h a s b e e n fo u n d to b e m ore p r e v a l e n t
in . Denmark t h a n t h e n e t form ( S m e d e g a r d -P e te r s e n , 1 9 7 2 ) .
T ekauz and
B uchannon (1 9 7 7 ) h a v e o b s e rv e d t h e s p o t form i n t h e W in n ip e g , M annito b a r e g i o n an d b e l i e v e t h a t i t s d i s t r i b u t i o n i n d i c a t e s t h i s b i o ty p e
may h a v e b e e n i n t r o d u c e d i n t o t h e r e g i o n on c o n ta m in a te d b a r l e y s e e d .
I n c r o s s e s b e tw e e n s p o t a n d n e t t y p e s o f
P. t2A U , i t w as fo u n d t h a t
-9 -
sympfcom e x p r e s s i o n i s c o n t r o l l e d by two in d e p e n d e n t a l l e l i c p a i r s o f
g e n e s ' ( S m e d e g a r d -P e te r s e n , 1 9 7 6 ).
Vytumophoha. -teA.64 h a s b e e n fo u n d t o p ro d u c e two t o x i n s , b o th
low m o le c u la r w e ig h t p e p t i d e s ( S m e d e g a r d -P e te r s e n , 1 9 7 6 , 1 9 7 7 a ).
E x c e p t f o r t h e n e t t i n g o r s p o t t i n g l e s i o n s , b o th t o x i n s i n c i t e m ost
o f t h e sym ptom s i n c i t e d by t h e p a th o g e n i t s e l f ,
n e c r o s i s an d i n c r e a s e d r e s p i r a t i o n .
i.e .;
c h lo ro s is ,
The two t o x i n s do n o t seem t o
d e te r m in e p a t h o g e n i c i t y , h o w e v e r, b u t r a t h e r th e y c o n t r i b u t e t o t h e
v i r u l e n c e o f t h e o r g a n is m
( S m e d e g a r d -P e te r s e n , 1 9 7 6 , 1 9 7 7 a , 1 9 7 7 b ).
U nder f i e l d c o n d i t i o n s , t h e n e t t e d l e s i o n s o f
c o a l e s c e w i t h t im e , fo rm in g l o n g i t u d i n a l s t r i p e s .
P;. t2AQJ> w i l l
T h e se s t r i p e s c a n
e x te n d t h e l e n g t h o f t h e b l a d e and i n t o t h e l e a f s h e a t h .
The s t r i p e s
r e s e m b le t h o s e n o r m a lly p ro d u c e d by
Py/i&nophoA/l g/uxmj.ne.ci, t h e c a u s a l
o r g a n is m o f b a r l e y s t r i p e d i s e a s e .
O f te n t h e symptom s o f t h e two
d is e a s e s , a re v i r t u a l l y in d is tin g u is h a b le .
The m o rp h o lo g y o f b o th t h e
s e x u a l and a s e x u a l s t a g e s o f t h e s e two s p e c i e s i s a l s o v e r y s i m i l a r ,.
a lt h o u g h t h e r e a r e some d i f f e r e n c e s .
a re l a r g e r th a n th o s e o f
ascus
( S c h o e m a k e r, ,1 9 6 2 ).
The a s c o s p o r e s o f
P. gA.CUV.lne.CL
P. te/ieA , and o n ly f o u r a r e p ro d u c e d i n e a c h
The c o n i d i a o f
t h e s e p t a a n d h a v e a n e n la r g e d b a s a l c e l l .
P. t-OAQA a r e c o n s t r i c t e d a t
T hose o f
P. gA.amlne.CL- do
n o t h a v e a n e n l a r g e d b a s a l c e l l and a r e n o t c o n s t r i c t e d a t t h e s e p t a .
The c o n i d i a o f
P. gAjCLmlne.CL m e a s u re 3 1 -1 1 1 x 1 1 -2 4 pm and a r e 1-7
s e p t a t e , and a r e s m a lle r th a n th o s e o f
P. IeA eA ( D r e c h s l e r , 1923;
—1 0 —
L u t t r e l l 5 1 9 5 1 ).
t h a n P.
P..
teAU a l s o s p o r u l a t e s m ore r e a d i l y i n c u l t u r e
g/Lamlnm.
The v a r i a b i l i t y in t h e s e m o r p h o lo g ic a l c h a r a c t e r i s t i c s Iijakes i t
d i f f i c u l t t o d i s t i n g u i s h b e tw e e n t h e two s p e c ie 's u s in g t h e m o rp h o lo g ­
i c a l d i f f e r e n c e s a s a k ey (.S m e d e g a rd - P e te r s e n 5 1 9 7 6 ; M e tz , 1 9 7 8 ).
p ro b le m i s f u r t h e r c o m p lic a te d by t h e f a c t t h a t i s o l a t e s o f
an d
The
P. - tQA2A
P. QMjn^ihtCL c a n b e c r o s s e d i n c u l t u r e a n d p e r i t h e c i a c o n t a i n i n g
v ia b le a s c o s p o re s can be o b ta in e d
( S m e d e g a r d -P e te r s e n , 1 9 7 6 ).
The ■
m o st r e l i a b l e m ethod o f d i s t i n g u i s h i n g b e tw e e n t h e two s p e c i e s i s i n
t h e i r mode o f i n f e c t i o n .
P. ttflU w i l l c a u s e i n f e c t i o n and symptom
d e v e lo p m e n t when s p r a y e d on t h e f o l i a g e o f s u s c e p t i b l e b a r l e y ,
w h ile
P. QH.ami.Yl2.0L c a n n o t i n f e c t b a r l e y i n t h i s m a n n e r.
P. QH-Omivita.
i s a f l o r a l i n f e c t i n g p a th o g e n and becom es s y s t e m i c , w h i l e
P. tQAQJs
does n o t s y s te m ic a lly in f e c t b a rle y .
N et b l o t c h i s fo u n d w h e re v e r b a r l e y i s grow n.
It
i s o f econom ic
im p o r ta n c e i n N o rth a n d S o u th A m e ric a , E u r o p e , A u s t r a l i a , t h e M id d le
E a s t and A f r i c a
( S h ip to n 5 e t a l . , 1 9 7 3 ).
and q u a l i t y h as f r e q u e n tl y been s tu d ie d .
The e f f e c t , on g r a i n y i e l d
,
Stakm an (1 9 2 2 ) e s ti m a t e d
l o s s e s o f 5% a n d 3% s t a t e w i d e f o r Iow a an d S o u th D a k o ta , r e s p e c t i v e l y .
S h ip to n (1 9 6 6 ) o b s e r v e d a 17.4% d e c r e a s e i n y i e l d i n c o n tr o l , p l o t s a s
com pared t o p l o t s p r o t e c t e d w i t h t h e f u n g i c i d e M atteb.
s e rv e d a s i g t t i f i c a n t r e d u c tio n in m a ltin g q u a li ty .
He a l s o o b ­
P i e n in g and K a u f-
mann (1 9 6 9 ) m e a s u re d y i e l d l o s s e s o f 53.3% an d a m arked r e d u c t i o n i n
-1 1 -
k e r n e l num ber p e r s p i k e , i n d i c a t i n g t h a t t h e e f f e c t b e g a n i n t h e e a r l y
s t a g e s o f p l a n t g ro w th .
l o s s e s o f 26% due t o P.
C ad d el and W ilc o x so n (1 9 7 5 ) r e p o r t e d y i e l d
tOASA. ' S m e d e g a r d -P e te rs e n (1 9 7 4 ) r e p o r t e d
y i e l d l o s s e s o f 9.0% an d 11.1% i n t h e b a r l e y c u l t i v a r s Wing and L a u d a ,
r e s p e c t i v e l y , due m a in ly t o r e d u c t i o n i n . g r a i n s i z e and w e ig h t.
C u ltu r a l ch an g es have le d to a r e c e n t in c r e a s e in th e p re v a le n c e
Of n e t b l o t c h .
C hanges r e s u l t i n g i n a n i n c r e a s e i n o v e r w in t e r i n g
in o c u lu m , su c h a s minimum t i l l a g e and c o n tin u o u s c r o p p i n g , and c h a n g e s
w h ich h a v e h e lp e d p ro d u c e a n e n v iro n m e n t m ore c o n d u c iv e t o d i s e a s e
s p r e a d , i . e . , i r r i g a t i o n , e a r l y s o w in g , and t h e p l a n t i n g o f s u s c e p ­
t i b l e v a r i e t i e s h a v e a l l h e lp e d t o p ro d u c e a s i t u a t i o n w h ic h le n d s
i t s e l f t o p o t e n t i a l d i s e a s e e p id e m ic s ( S m e d e g a r d - P e te r s e n , 1971: S h ip t o n , e t a l . , 1 9 7 3 ).
T h e se c u l t u r a l p r a c t i c e s a r e m ore b e n e f i c i a l t h a n h a r m f u l.
t r o l o f t h i s d i s e a s e m u st t h e r e f o r e u t i l i z e o t h e r m e th o d s .
s p r a y s a r e e f f e c t i v e , b u t the; c o s t i s p r o h i b i t i v e .
Con­
F o lia r
S eed t r e a t m e n t i s
h e l p f u l , b u t w i l l n o t c o m p le te ly c o n t r o l t h e d i s e a s e .
The u s e o f r e ­
s i s t a n t v a r i e t i e s i s t h e m o st e f f i c i e n t and d e s i r a b l e m eans o f c o n t r o l ­
l in g n e t b lo tc h .
R e s is ta n t v a r i e t i e s , in a d d itio n to s u ffe rin g l e s s
y i e l d l o s s , a l s o slo w t h e s p r e a d o f d i s e a s e d u r in g t h e g ro w in g s e a s o n
and p r o v id e l e s s i n f e c t e d p l a n t d e b r i s , t h u s r e d u c i n g t h e s o u rc e o f
p r im a r y in o c u lu m f o r t h e f o ll o w i n g y e a r .
R e s i s t a n t v a r i e t i e s a p p a r e n t l y h a v e no e f f e c t on s p o r e g e r m in a tio n
-1 2 -
t h e num ber o f g e rm tu b e s p r o d u c e d , t h e l e n g t h and b r a n c h i n g o f germ t u b e s o r t h e num ber o f p e n e t r a t i o n s
( K e e lin g and B a n t t a r i . , 1 9 7 5 ).
I n h i b i t i o n o f h y p h a l g ro w th i s p ro n o u n c e d a f t e r p e n e t r a t i o n and many
i n f e c t i o n s do n o t p r o g r e s s bey o n d t h e p e n e t r a t e d c e l l .
The o rg a n is m
t h e r e f o r e c a u s e s fe w e r an d s m a l l e r l e s i o n s on r e s i s t a n t p l a n t s th a n
on s u s c e p t i b l e p l a n t s .
S p o r u l a t i o n o f t h e fu n g u s on e x c is e d l e a v e s
o f r e s i s t a n t p l a n t s was a l s o fo u n d t o b e l e s s t h a n on l e a v e s o f s u s - .
c e p tib le p la n ts
( K e e lin g a n d B a n t t a r i , 1 9 7 5 ).
T ekauz and B uchannon
(1 9 7 7 ) fo u n d t h a t t h e tim e r e q u i r e d f o r s p o r u l a t i o n o f c o n i d i a on
e x c is e d l e a v e s v a r i e d from l e s s t h a n t w e n ty - f o u r h o u r s w i t h s u s c e p ­
t i b l e v a r i e t i e s to n in e ty - s ix h o u rs f o r r e s i s t a n t v a r i e t i e s .
The f i r s t e x t e n s i v e s c r e e n i n g o f b a r l e y l i n e s f o r s o u r c e s o f
r e s i s t a n c e w as do n e b y S c h a l l e r an d W iebe ( 1 9 5 2 ).
b a r l e y l i n e s was t e s t e d t o C a l i f o r n i a i s o l a t e s o f
A t o t a l o f 4 ,5 2 6
P. toJiQA.
T w enty-
f i v e h i g h l y r e s i s t a n t l i n e s w ere f o u n d , w i t h t h e g r e a t e s t p e r c e n ta g e
o f t h e s e o r i g i n a t i n g i n M a n c h u ria .
B uchannon and M cDonald (1965)
■ te s te d 6 ,1 7 4 b a r l e y l i n e s f o r r e s i s t a n c e t o n e t b l o t c h .
Of t h e s e
th e y fo u n d f o r t y l i n e s , s e v e n te e n o r i g i n a t i n g i n E t h i o p i a , w h ich w e re
r e s i s t a n t in th e s e e d lin g s ta g e .to
M exico and t h e U n ite d S t a t e s .
is o la te s of
P. toA-HA fro m C an ad a,
Khan a n d Boyd (1 9 6 9 a ) u s e d s e v e n te e n
A u s t r a l i a n , i s o l a t e s t o s c r e e n 142 b a r l e y l i n e s w h ic h h a s p r e v i o u s l y
been r e p o r te d to be r e s i s t a n t to n e t b lo tc h .
and tw e n ty -tw o r e s i s t a n t l i n e s ,
T w elve h i g h l y r e s i s t a n t
from b o th M a n c h u ria and E t h i o p i a ,
-1 3 -
w e re fo u n d , w ith t h e E t h io p i a n l i n e s g e n e r a l l y e x h i b i t i n g a .h ig h e r
d e g re e o f r e s i s t a n c e t h a n t h e M a n c h u ria n l i n e s .
E ig h ty b a r l e y l i n e s ,
o u t o f 2 ,6 0 8 l i n e s t e s t e d , w ere fo u n d by C ad d el an d W ilc o x so n (19 7 5 )
t o . b e r e s i s t a n t t o M oroccan i s o l a t e s o f
P.
M e tc a lfe , e t a l .
( 1 9 7 8 ), e v a l u a t e d 226 E t h i o p i a n b a r l e y l i n e s and fo u n d t h i s r e g i o n t o
b e a good s o u r c e .o f r e s i s t a n c e to i s o l a t e s o f
P. £<ZJIQA fro m C anada.
I s o l a t e s fro m v a r i o u s g e o g r a p h ic a r e a s d i f f e r s i g n i f i c a n t l y i n
p a th o g e n ic ity .
The p h y s i o l o g i c s p e c i a l i z a t i o n o f
P. toAU becam e
a p p a re n t w ith th e s c re e n in g o f d i f f e r e n t b a rle y l i n e s .
.The l i n e s fo u n d
by S c h a l l e r and W iebe (1952) t o b e r e s i s t a n t t o C a l i f o r n i a i s o l a t e s
of
P. t2AgJ> w e re s u s c e p t i b l e t o C a n a d ia n i s o l a t e s (B uchannon and Mc­
D o n a ld , 1 9 6 5 ) .
M ost b a r l e y l i n e s r e s i s t a n t t o
P. t&i&A e ls e w h e r e i n
t h e w o r ld p ro v e d t o b e s u s c e p t i b l e o r m o d e r a te ly s u s c e p t i b l e to Mor­
occan i s o la te s
fo rm o f
( C a d d e l an d W ilc o x s o n , 1 9 7 5 ).
I n g e n e r a l , t h e s p o t. .
P. tdAZA fo u n d i n C anada i s l e s s v i r u l e n t t h a n t h e n e t ty p e s
when l e s i o n c h a r a c t e r i s t i c s a n d e x t e n t o f c h l o r o s i s a r e com pared
(T ekauz an d M i l l s , 1 9 7 4 ).
T h is i s n o t t h e c a s e i n D enm ark, w here t h e .
s p o t fo rm i s m ore p r e v a l e n t th a n t h e n e t form ( S m e d e g a r d -P e te r s e n ,.
1 9 7 1 , 1 9 7 6 ).
Khan an d Boyd (1 9 6 9 a ) s e p a r a t e d i s o l a t e s o f
P. teAU .
from W e ste rn A u s t r a l i a i n t o t h r e e d i f f e r e n t v i r u l e n c e t y p e s u s in g
two d i f f e r e n t i a l v a r i e t i e s .
The f i r s t s tu d y to d e te r m in e t h e g e n e t i c s o f r e s i s t a n c e to
was done by S c h a l l e r
( 1 9 5 5 ).
P. tQJiZA
He fo u n d t h a t T if a n g c o n t a i n s a s i n g l e
—1 4 —
i n c o m p le t e ly d o m in a n t' g e n e f o r r e s i s t a n c e e f f e c t i v e a g a i n s t a . C a l i f o r n i a
is o la te .
The sym bol P t was s u g g e s te d f o r t h i s g e n e .
Mode an d S c h a l l e r
' I
(1 9 5 8 ) d e s i g n a t e d t h e r e s i s t a n c e g e n e i n T if a n g P t ^ .
They found C . I .
4 7 9 7 , C . I . 739 a n d C . I . 4929 c o n t a i n a s i n g l e g en e f o r r e s i s t a n c e , d e ­
s i g n a t e d P t g , and C . I . 2750 an d C . I . 4922 c o n t a i n two g e n e s f o r r e s i s ­
t a n c e , d e s i g n a t e d P tg an d P t ^ .
I t w as fo u n d t h a t P t^ a n d P tg a r e c l o s e l y
l i n k e d , w i t h a 2.57% r e c o m b in a t io n ,
P t_ i s in d e p e n d e n t o f P t 1 and P t 0 .
j
I
Z
Khan and Boyd (1 9 6 9 c ) fo u n d C . I . 2 3 3 0 , C . I . 4797 and, T if a n g t o c o n t a i n
tHAQA.
a s i n g l e g en e f o r r e s i s t a n c e to a W e ste rn A u s t r a l i a n i s o l a t e o f P.
C .I .
9819 a n d C . I . 5791 c o n ta i n e d two d o m in a n t g e n e s f o r r e s i s t a n c e t o
th is is o la te .
A l l f i v e v a r i e t i e s h a v e a common g e n e f o r r e s i s t a n c e t o
t h i s i s o l a t e o f P.
'
T if a n g a n d C . I . 4797 c a r r y l i n k e d g e n e s , P t^ a n d P t g , r e s p e c ­
t i v e l y , f o r r e s i s t a n c e to a C a lif o r n ia i s o l a t e o f
lin e s a ls o c a rry an a l l e l i c
fro m W e s te rn A u s t r a l i a .
P.
.
T h ese two
gene fo r r e s i s t a n c e to i s o l a t e s o f
P. to A Z A
S in c e n e i t h e r T if a h g n o r C . I . 4797 c a r r y th e
g e n e P t ^ , t h e common g e n e e f f e c t i v e a g a i n s t t h e A u s t r a l i a n i s o l a t e
w ould n e e d t o b e a f o u r t h g e n e .
T h is g en e was d e s i g n a t e d P t^ by Khan
and Boyd ( 1 9 6 9 c ) .
B o cklem an, e t a l .
( 1 9 7 7 ), u t i l i z i n g t r i s o m i c a n a l y s i s , found
T if a n g t o c o n t a i n a s i n g l e d o m in a n t g e n e f o r r e s i s t a n c e e f f e c t i v e
a g a i n s t a T u n i s ia n i s o l a t e o f
chrom osom e 3.
P. -teA.64.
The g e n e w as l o c a t e d on
C .I . 7584 a l s o c o n t a i n s a s i n g l e d o m in a n t g e n e f o r
.
-1 5 -
r e s i s t a n c e , l o c a t e d on chrom osom e 2 , e f f e c t i v e a g a i n s t t h i s i s o l a t e .
C . I . 9819 c o n t a i n s two d o m in a n t g e n e s , on chrom osom es 3 and 5 , e f f e c t i v e
a g a i n s t t h i s i s o l a t e o f P.
teJl&A.
E n v iro n m e n t a p p e a r s t o a f f e c t t h e e x p r e s s i o n o f r e s i s t a n c e t o P.
t'&iU.
H igh i n o c u l a t i o n a n d p o s t - i n o c u l a t i o n t e m p e r a t u r e s b r i n g a b o u t
a b rea k d o w n i n r e s i s t a n c e
1 9 7 7 ).
(Khan a n d B oyd, 1 9 6 9 ; T ekauz and. B u ch an n o n ,
L ig h t i n t e n s i t y , h i g h p r e - i n o c u l a t i o n t e m p e r a t u r e s and s p o re
c o n c e n t r a t i o n w i l l a l s o a f f e c t t h e e x p r e s s i o n o f r e s i s t a n c e i n some
v a rie tie s
(Khan a n d B oyd, 1 9 6 9 b ).
C o n s is te n c y o f e x p r e s s i o n o f r e s i s t a n c e i s a l s o a v a r i e t a l c h a r ­
a c t e r i s t i c a n d i s d e p e n d e n t on t h e g e n e t i c b a c k g ro u n d o f t h e h o s t .
T h is i s e s p e c i a l l y i m p o r ta n t when l i n e s a r e c r o s s e d .
The p e n e tr a n c e
and e x p r e s s i v i t y o f t h e r e s i s t a n c e g e n e s a r e h i g h l y d e p e n d e n t upon
t h e g e n e t i c b a c k g ro u n d o f t h e p a r e n t s u s e d i n t h e c r o s s , e v e n t h e b a c k ­
g ro u n d o f a s u s c e p t i b l e p a r e n t (K han, 1 9 6 9 ; Khan and B oyd, 1969b,
1 9 6 9 c).
Khan ( 1 9 6 9 ) , u s i n g . C .I .
5791 a s a r e s i s t a n t p a r e n t and A t l a s
a n d D am pier a s s u s c e p t i b l e p a r e n t s showed t h a t
h o s t r e a c ti o n and
F0 s e g r e g a t i o n p a t t e r n s a r e c o n s i d e r a b l y i n f l u e n c e d by t h e c h o ic e o f
s u s c e p t i b l e p a r e n t , w i t h l e s s r e s i s t a n c e b e in g e x p r e s s e d i n th e A t l a s x
C .I . 5791 c r o s s t h a n t h e D am pier x C . I . 5791 c r o s s .
C h a p ter I
THE EFFECT OF DIFFERENT GROOTH MEDIA ON
THE SPORULATION OF ?ytimopkoha t<>AQA
F o r a l l I n o c u l a t i o n s done i n t h i s s t u d y , c o n d i a l s u s p e n s io n s w ere
u s e d a s in o c u lu m .
S in c e a n a d e q u a te c o n c e n t r a t i o n o f c o n i d i a i n t h e
s u s p e n s io n i s n e e d e d t o o b t a i n a s a t i s f a c t o r y i n f e c t i o n , a n d h e n c e good
symptom d e v e lo p m e n t, i t
i s i m p o r ta n t t h a t t h e c u l t u r e s o f P .
d u c e a d e q u a te am o u n ts o f c o n i d i a .
t&lM p r o ­
I n t h i s e x p e r im e n t, d i f f e r e n t t y p e s
o f g ro w th m ed ia w e re t e s t e d t o d e te r m in e w h ic h t y p e w ould be m ost f a v ­
o r a b l e f o r s p o r u l a t i o n o f P.
.
M a t e r i a l s a n d M ethods .
One i s o l a t e o f P .
im e n t.
, P t S ( S id n e y , M t.), was u s e d i n th e e x p e r ­
E ig h t d i f f e r e n t t y p e s o f g ro w th m ed ia w e re t e s t e d , V8 i u i c e a g a r
P o t a t o d e x t r o s e a g a r ( D i f c o ) , M o d if ie d E c k e r t 's M edium , C z a p e c k *1s a g a r
( D i f c o ) , B a r le y l e a f e x t r a c t a g a r , M y c o p h il a g a r (BBL), Lima b e a n a g a r
( D i f c o ) , a n d R ic e c e r e a l a g a r .
I
S ix r e p l i c a t i o n s of. t h e e x p e r im e n t w e re c a r r i e d o u t .
For t h e i n i ­
t i a l t r a n s f e r o f P> -£eA&6 to t h e d i f f e r e n t a g a r t y p e s , s i n g l e s p o r e ,
t r a n s f e r s from l e a f t i s s u e w e re m ade.
T r a n s f e r s f o r s u b s e q u e n t .r e p l i c a ­
t i o n s w e re d o n e a s m ass s p o r e t r a n s f e r s u s i n g a d i s s e c t i n g n e e d l e , and
R e c ip e s o f t h e s e a g a r t y p e s a r e i n c l u d e d i n t h e a p p e n d ix .
-1 7 -
t r a n s f e r l n g s p o r e s t o f o u i s p o t s on e a c h p e t r i p l a t e .
T r a n s f e r s to
f r e s h p l a t e s w e r e . made u s in g s p o r e s o n ly fro m p l a t e s o f t h e same a g a r
ty p e .
S p o re s w e re t r a n s f e r r e d t o f o u r p l a t e s o f e a c h a g a r t y p e , t h r e e
o f t h e s e t o b e u s e d f o r c o u n tin g a n d t h e f o u r t h a s a s o u r c e f o r t h e n e x t
tra n s fe r.
S p o re s w e re c o u n te d s e v e n d a y s a f t e r t r a n s f e r r i n g .
C o u n ts w e re
made by f l o o d i n g t h e p l a t e s w i t h d i s t i l l e d w a t e r , s c r a p i n g th e s p o r e s
l o o s e w i t h a m ic r o s c o p e s l i d e a n d s t r a i n i n g t h e s u s p e n s i o n th ro u g h
th r e e la y e r s o f c h e e s e c lo th .
was u s e d p e r t h r e e p l a t e s .
A t o t a l o f 65 ml o f d i s t i l l e d w a te r
The s p o r e c o n c e n t r a t i o n o f t h e r e s u l t i n g
s u s p e n s i o n was th e n m e a s u re d u s in g a Howard Mold C o u n tin g Chamber
(H a u s s e r S c i e n t i f i c ) .
T h re e c o u n ts w e re m ade, w ith t h e a v e r a g e o f
th e s e u sed a s th e sp o re c o n c e n tra tio n f o r th a t a g a r ty p e .
The c u l t u r e s w e re grow n i n a n i n c u b a t i o n cham ber w i t h a 12 h o u r
p h o t o p e r i o d and a te m p e r a t u r e o f 1 7 -1 8 ° C.
R e s u l t s a n d D is c u s s i o n
T a b le I show s t h e s p o r e c o n c e n t r a t i o n s f o r e a c h a g a r ty p e a t e a c h
t r a n s f e r an d a l s o t h e a v e r a g e num ber o f s p o r e s p e r nil f o r t h e d i f f e r ­
e n t ag ar ty p e s .
An a n a l y s i s o f v a r i a n c e w as p e rfo rm e d on th e d a t a i n
t h i s t a b l e , . a s shown b e lo w . '
-1 8 -
SOURCE
SS
T o ta l
2 4 4 .2 9 3
X
IO 8
A gar Type
1 3 2 .7 4 5
X
IO8 .
E rro r
1 1 1 .5 4 8
X
IO8
.
DE
MS
F
47
—------
—---- —
“ ■
—.
6 .8
2 .2 5
7
40
1 8 .9 6 4
IO8
X
1 .0 5
2 .7 8 9 x IO8
The r e s u l t s I n d i c a t e t h a t t h e r e i s a s i g n i f i c a n t d i f f e r e n c e . i n t h e
s p o ru la tio n o f
P. toAZb w i t h r e s p e c t t o a g a r t y p e .
To d e te r m in e w h ic h a v e r a g e s w e re s i g n i f i c a n t l y d i f f e r e n t , a D u n c a n 's
M u l t i p l e Range t e s t w as u t i l i z e d .
The r e s u l t s o f t h i s
t e s t a re in d ic a te d
i n T a b le I .
Lima b e a n a g a r (LBA), V8 j u i c e a g a r (V 8 ), M y c o p h il a g a r (MyA) an d
B a r le y l e a f e x t r a c t a g a r (BLEA) a l l a llo w e d a b u n d a n t s p o r u l a t i o n o f
P.
.
P o t a to d e x t r o s e a g a r (PDA), M o d ifie d E c k e r t 's Medium (MEM)
and R ic e c e r e a l a g a r (RCA) w e re l e s s f a v o r a b l e f o r s p o r u l a t i o n , w h ile
C z a p e c k 's a g a r (CzA) was l e a s t s u i t a b l e a s a g ro w th m edium .
• The r e s u l t s i n d i c a t e t h a t t h e ty p e o f g ro w th medium u s e d h a s a
s i g n i f i c a n t e f f e c t on t h e s p o r u l a t i o n o f
P.
.
P . t-QAU s p o r u l a t e s
w e l l enough on LBA, V8, BLEA and MyA t h a t any o f t h e s e s h o u ld b e a d e q u a te
a s a g ro w th medium f o r t h i s o r g a n is m .
T a b le 1 - 1 .
D if f e r e n tia l s p o ru la tio n
( s p o r e s /m l)
of
P.
toAeJ> on e i g h t ty p e s o f g ro w th m e d ia .
MEDIUM
1st
tra n s fe r
2nd
tra n s fe r
3 rd
tra n s fe r
4 th
tra n s fe r
5th
tra n s fe r
6 th
tra n s fe r
a v e ra g e
( s p o r e s /m l)
I
LBA
5 9 ,0 8 1 .9
4 9 ,9 2 8 .4
2 1 ,8 2 8 .6
5 2 ,2 0 7 .7
6 2 ,3 8 8 .1
4 9 ,8 1 9 ,9
4 9 ,2 0 0 .8 A2
'
6 6 ,1 0 0 .9
4 7 ,6 4 9 .1
3 3 ,2 8 5 .6
4 8 ,9 5 1 .5
5 4 ,1 6 1 .5
4 2 ,3 3 0 .6
4 8 ,7 4 6 .5 A
MyA ■■ ■■
5 7 ,6 3 4 .7
3 2 ,9 2 3 .8
2 8 ,4 6 1 .6
3 4 ,1 1 7 .7
7 8 ,5 1 0 .6
1 0 ,4 9 2 .2
4 0 ,3 5 6 .8 A
BLEA
4 1 ,2 4 5 .2
6 2 ,8 4 4 .7
8 ,3 2 1 .4
2 7 ,7 5 0 .1
7 3 ,8 0 7 .2
2 6 ,6 6 4 .7
4 0 ,1 0 5 .6 A
PDA
4 7 ,3 9 5 .8
2 3 ,0 4 6 .7
1 2 ,0 6 0 .0
1 9 ,8 9 9 .0
7 5 ,1 4 5 .9
2 7 ,9 6 7 .1
3 4 ,2 5 3 .9 AB
MEM ’ -
2 0 ,8 7 5 .9
8 ,3 2 1 .4
7 ,8 3 9 .0
2 5 ,5 7 9 .3
6 ,9 8 2 .7
2 2 ,0 6 9 .8
1 5 ,2 7 8 .0 BC
RCA
1 8 ,9 2 2 .1
1 3 ,9 2 2 .1
7 ,8 3 9 .0
1 0 ,9 6 2 .5
3 3 ,6 4 7 .4
3 ,2 5 6 .2
1 4 ,6 8 7 .1 BC
CzA
3 ,0 0 2 .9
1 ,0 8 5 .4
1 ,6 8 8 .4
1 ,4 4 7 .2
1 ,0 8 5 .4
3 6 1 .8
V8
1 ,4 4 5 .2 C
I)
LBA: Lim a b e a n a g a r , V 8: V8 j u i c e a g a r . MyA: M y c o p h il a g a r , BLEA: B a r le y l e a f e x t r a c t
a g a r , PDA: P o t a t o d e x t r o s e a g a r , MEM: M o d ifie d E c k e r t 's M edium, RCA: R ice- c e r e a l a g a r ,
CzA: C z a p e c k 's a g a r
2)
A v e ra g e s f o llo w e d by d i f f e r e n t l e t t e r s d i f f e r s i g n i f i c a n t l y a t P = .0 5 p r o b a b i l i t y l e v e l .
C h a p ter 2
EFFECT OF PHOTOPERIOD AND TYPE OF GROWTH MEDIUM
ON THE SPORULATION OF P. tQAQA
I n t h e p r e v i o u s e x p e rim e n t d i f f e r e n t t y p e s o f g ro w th m ed ia w e re
t e s t e d f o r t h e i r e f f e c t i v e n e s s i n in d u c in g t h e s p o r u l a t i o n o f P.
B ased on t h e am ount o f s p o r u l a t i o n ,
t<lA.2A.
f o u r a g a r t y p e s w e re found t o b e
p a rtic u la rly e ffe c tiv e .
I n t h i s e x p e r i m e n t , t h e s e f o u r a g a r t y p e s , M y c o p h il a g a r (BBL),
Lima b e a n a g a r ( D i f c o ) , VB j u i c e a g a r and B a r le y l e a f e x t r a c t a g a r ,
w ere a g a i n u s e d .
T h e se w ere t e s t e d o v e r a r a n g e o f p h o t o p e r i o d s i n a n
e f f o r t t o d e te r m in e a n optim um p h o t o p e r i o d and a g a r t y p e .
M a t e r i a l s a n d M ethods
The same i s o l a t e u s e d p r e v i o u s l y , P t S ( S id n e y , MT), was u s e d i n
t h i s e x p e r im e n t.
The f o u r t y p e s o f g ro w th m ed ia w e re p r e p a r e d f o l l o w i n g
t h e p r o c e d u r e s i n A p p en d ix A.
S ev en d i f f e r e n t p h o t o p e r i o d s w ere u s e d ;
no l i g h t , 8 h r . , 12 h r . , 16 h r . , 20 h r . , 22 h r . , and 24 h r . o f l i g h t .
T e m p e ra tu re i n t h e g ro w th cham ber was m a in ta in e d a t 1 7 -1 8 ° C, w ith a
p h o t o p e r i o d o f 24 h r . o f l i g h t .
C u l t u r e s grown u n d e r s h o r t e r p h o to ­
p e r i o d s w e re p l a c e d i n c a r d b o a r d b o x e s and w rap p ed i n alum inum f o i l
d u r in g t h e d a r k p e r i o d .
p e rio d .
A ll f o u r a g a r t y p e s w ere t e s t e d a t e a c h p h o to ­
S p o re s w e re i n i t i a l l y
th e . f o u r a g a r t y p e s .
t r a n s f e r r e d from l e a f t i s s u e to p l a t e s o f
T h e se c u l t u r e s w ere th e n grow n a t t h e d i f f e r e n t
p h o to p e rio d s f o r sev en d a y s.
The am ount o f s p o r u l a t i o n was t h e n
—2 1 —
d e te r m in e d i n t h e m an n er d e s c r i b e d p r e v i o u s l y .
Four s u c c e s s iv e r e p l i ­
c a t i o n s w e re r u n .
R e s u l t s and D i s c u s s i o n
T a b le 2 -1 ( a - g ) show s t h e s p p r u l a t i o n o f P. -teA.e-6 on t h e d i f f e r e n t ■
a g a r ty p e s a t each p h o to p e rio d .
The v a l u e s w e re u s e d t o d e te r m in e t h e
a v e r a g e s p o r u l a t i o n a t e a c h p h o to p e r io d o v e r a l l a g a r t y p e s (T a b le 2 - 2 )
and f o r e a c h a g a r ty p e o v e r a l l p h o t o p e r i o d s (T a b le 2 - 3 ) .
An a n a l y s i s
o f v a r i a n c e t e s t w as t h e n com puted t o d e te r m in e w h ic h a v e r a g e s w ere s i g ­
n ific a n tly d iffe re n t
t i o n o f P.
( T a b le 2 - 4 ) .
B e c a u se o f t h e e x tr e m e ly low s p o r u l a ­
teAZA u n d e r c o n d i t i o n s o f no l i g h t , th e d a t e i n T a b le 2 -1 ( a )
w e re n o t i n c l u d e d .
The r e s u l t s o f t h e a n a l y s i s o f v a r i a n c e t e s t i n d i c a t e t h a t t h e
d i f f e r e n c e s w i t h i n r e p l i c a t i o n s , p h o t o p e r i o d s , r e p l i c a t i o n s x n h o to p e r i o d i n t e r a c t i o n a n d r e p l i c a t i o n x a g a r t y p e i n t e r a c t i o n w ere s t a t i s t i ­
c a l l y s i g n i f i c a n t , w h ile t h e d i f f e r e n c e s w i t h i n a g a r t y p e s and a g a r t y p e
x p h o t o p e r i o d i n t e r a c t i o n w ere n o t s t a t i s t i c a l l y
s ig n ific a n t.
T h e se r e ­
s u l t s i n d i c a t e t h a t t h e d i f f e r e n t a g a r t y p e s d id n o t s i g n i f i c a n t l y a f ­
f e c t t h e s p o r u l a t i o n o f P.
c u l t u r e s o f P..
£<Lfvi6, w h i l e t h e p h o to p e r io d u n d e r w h ich t h e
£<L>tU w ere grow n d id h a v e a s i g n i f i c a n t e f f e c t upon
s p o ru la tio n .
A D u n c a n 's M u l t i p l e R ange T e s t was u t i l i z e d t o d e te r m in e w h ich
p h o to p e rio d s d i f f e r e d s i g n i f i c a n t l y
show t h a t t h e s p o r u l a t i o n o f P.
(T a b le 2 - 2 ) .
The r e s u l t s o f t h i s t e s t
£ qAZ& u n d e r a p h o to p e r io d o f e i g h t h o u r s
-2 2 -
was s i g n i f i c a n t l y h i g h e r t h a n t h e s p d r u l a t i o n u n d e r a n y o t h e r p h o to ­
p e rio d .
The r e s u l t s a l s o i n d i c a t e t h a t s p o r u l a t i o n i n c r e a s e s s i g n i '
f i c a n t l y a s t h e p h o t o p e r i o d d e c r e a s e s . . B ecau'se o f t h e v e r y low s p tif u .
,
■'
l a t i o n w i t h no l i g h t , i t i s e v i d e n t t h a t some l i g h t i s n e c e s s a r y :
The
r e s u l t s o b ta in e d in t h i s t e s t i n d ic a te t h a t o f th e sev en d i f f e r e n t
p h o to p e rio d s t e s t e d , an e ig h t h o u r p h o to p e rio d i s b e s t f o r s p o r u la tio n
of P.
.
T h e se r e s u l t s a l s o i n d i c a t e t h a t i t w o u ld b e w o r th w h ile
t o t e s t the. s p o r u l a t i o n o f
P . . tQA2M grow n u n d e r p h o t o p e r i o d s s h o r t e r
th a n e ig h t h o u rs .
T h e re i s a p a u c i t y o f s t u d i e s i n v o l v i n g t h e e f f e c t o f e n v iro n m e n t
i
on s p o r u l a t i o n o f P. -teA.^6. O n e s i r o s a n . and B a n t t a r i (1 9 6 9 ) s t u d i e d
t h e e f f e c t o f l i g h t an d t e m p e r a t u r e on s p o r u l a t i o n .
U sin g p h o to p e r io d s
o f no l i g h t , 12 h r . l i g h t and 24 h r . l i g h t , th e y fo u n d a 12 h r . p h o to ­
p e r i o d m o st c o n d u c iv e t o s p o r u l a t i o n .
They a l s o s t u d i e d t h e e f f e c t o f
l i g h t q u a l i t y , and fo u n d t h a t u l t r a v i o l e t l i g h t w i t h w a v e le n g th s o f
3 1 0 -3 5 5 pm was n e c e s s a r y f o r c o n id i o p h o r e f o r m a ti o n .
C o n id ia p r o d u c t i o n
was m o st f a v o r e d i n t h e a b s e n c e o f l i g h t o r i n t h e a b s e n c e o f l i g h t o f
w a v e le n g th s 3 5 5 -4 9 5 pm.
I t a p p e a r s t h a t s t i m u l a t i o n o f c o n id io p h o r e
p r o d u c t i o n i s c r i t i c a l , and o n c e t h i s i s a c c o m p lis h e d , p r o d u c t i o n
.
o f c o n i d i a i s n o t l i g h t d e p e n d e n t.
'
'
.
One, m ig h t b e a b l e t o o b t a i n m a x i­
mum s p o r u l a t i o n by g ro w in g t h e c u l t u r e s i n o n ly u l t r a v i o l e t l i g h t .
A lth o u g h n o t s i g n i f i c a n t l y s o , t h e s p o r u l a t i o n o f
m y c o p h il a g a r was h i g h e r t h a n on t h e o t h e r a g a r t y p e s .
P. X.QJ12A on
For th is
\
-2 3 -
r e a s o n t h e e n t i r e c o l l e c t i o n was t r a n s f e r r e d t o p l a t e s o f m y c o o h il a g a r .
T h is r e s u l t e d i n a d i f f e r e n t i a l r a n g e o f r e a c t i o n s o f t h e i s o l a t e s to
t h i s a g a r ty p e .
I t a p p e a r e d t h a t c e r t a i n i s o l a t e s grew a n d s o o r u l a t e d
w e l l on i t . w h i l e , o t h e r s s p o r u l a t e d v e r y p o o r ly .
S in c e a l l i s o l a t e s
s p o r u l a t e d r e a s o n a b l y w e l l on V8 j u i c e a g a r and s i n c e t h e s p o r u l a t i o n
o f P.
‘
t& lte on ‘t h e two a g a r s i n t h i s t e s t w as n o t s i g n i f i c a n t l y d i f ­
f e r e n t , i t was d e c id e d t h a t t h e c u l t u r e s w ould b e m a i n ta i n e d o n ■V 8.
ju ic e a g a r.
U sin g V8 j u i c e a g a r a s a g ro w th m edium , and u s in g a b h p to p e r io d
o f 8 h r . p r o d u c e s h i g h l y s p o r u l a t i n g c u l t u r e s o f P.
teJUlA.
A d e q u a te ly
h ig h c o n c e n t r a t i o n s o f c o n i d i a a r e o b t a i n e d to , p ro d u c e r e a d a b l e , d i f ­
fe re n tia tin g
sym ptom s on b a r l e y p l a n t s .
■ ,<
I
I• I
-2 4 -
T a b le 2 - 1 .
S p o r u l a t i o n ( s p o r e s /m l) o f P. tdh.2A Ion d i f f e r e n t a g a r t y p e s
a t d i f f e r e n t p h o to p e rio d s
2 - 1 ( a ) ; No l i g h t
A gar ty p e
V8
•
I
4 th
tra n s fe r
1 st
tra n s fe r
2nd
tra n s fe r
3 rd
tra n s fe r
0 .0
1 0 8 .5
. 1 0 8 .5
. 0 .0
5 4 .3
4 7 0 .3
0 .0
' 1 0 8 .5
'■ 1 4 4 .7
. 2 5 3 .3
4 7 0 .3
■2 4 2 .4
2 4 1 .5
1 0 8 .5
1 ,1 9 3 .9
1 ,0 8 5 .4
5 9 7 .0
LBA
0 .0
HyA
0 .0
BLEA
0 .0
.
.
a v e ra g e
. ( s p o r e s /m l)
^VS = V8 j u i c e a g a r , LBA = Lima b e a n , a g a r , MyA = M y c o p h il a g a r , BLEA =
B a r le y l e a f e x t r a c t a g a r
2 - 1 ( b ) ; 8 H ours o f l i g h t
A gar ty p e
V8
1st
tra n s fe r
3 6 1 .8 ■
2nd
tra n s fe r
. 3 rd
tra n s fe r
4 th
tra n s fe r
a v e ra g e
( s p o r e s /m l)
6 2 ,5 9 1 .4
4 5 ,1 0 4 .4
7 9 ,1 3 3 .6
4 6 ,7 9 2 .8
LBA
5 ,4 2 7 .0
5 5 ,2 3 4 .8
5 8 ,1 2 9 .2
7 9 ,2 3 4 .2
4 9 ,5 0 6 .3
MyA
2 ,0 6 2 .3
9 9 ,6 1 5 .8
7 8 ,4 0 2 .1
7 0 ,7 9 2 .2
6 2 ,7 1 8 .1
BLEA
6 ,1 5 0 .6
4 7 ,3 9 5 .8
4 1 ,6 0 7 .0
9 1 ,6 5 6 .0
4 6 ,7 0 2 .4
I
-25-
2 - l ( c ) ; 12 H ours o f l i g h t
1 st
tra n s fe r
2nd
tra n s fe r
V8
4 6 ,0 5 7 .1
LBA
MyA
A gar ty p e
■ BLEA
3 rd
tra n s fe r
4 th
tra n s fe r
a v e ra g e
( s p o r e s /m l)
■ 1 7 ,3 6 6 .4
5 ,8 9 7 .3
6 4 ,6 4 1 .6
3 3 ,4 9 0 .6
4 0 ,1 5 9 .8
1 7 ,6 1 9 .7
9 ,2 9 8 .3
6 1 ,8 6 7 .8
3 2 ,2 3 6 .4
1 6 ,6 4 2 .8
' 1 1 ,5 7 7 .6
3 6 1 .8
8 4 ,7 8 1 .8
2 8 ,3 3 3 .5
8 ,9 3 6 .5
7 2 3 .6
4 2 ,3 3 0 .6
3 0 ,2 1 5 .4
3 rd
tra n s fe r .
4 th
tra n s fe r
a v e ra g e
( s p o r e s /m l)
6 8 ,8 7 0 .7 ■
2 - l ( d ) ; 16 H ours o f l i g h t
1st
tra n s fe r
2nd
tra n s fe r
V8
3 4 ,7 3 2 .8
5 ,4 2 7 .0
1 4 ,3 6 3 .7
3 6 ,0 5 9 .4
2 2 ,6 4 5 .7
LBA '.
3 9 ,3 2 7 .7
1 0 ,4 9 2 .2
7 ,3 4 4 .'5
3 4 ,8 5 3 .4
2 3 ,0 5 4 .5
MyA
1 9 ,5 3 7 .2
1 3 ,1 3 3 .3
3 ,5 0 9 .5
8 6 ,3 4 9 .6
3 0 ,6 3 2 .4
BLEA
5 1 ,0 1 3 .8
3 ,9 7 9 .8
5 ,4 2 7 .0
3 1 ,4 7 6 .6
2 2 ,9 7 4 .3
. . 2nd
tra n s fe r
3 rd
tra n s fe r
4 th
tra n s fe r
a v e ra g e
( s p o r e s /m l)
A gar ty p e
2 - 1 ( e ) ; 20 H ours o f l i g h t
A gar t y p e .
1st
tra n s fe r .
V8
2 1 ,9 6 1 .3
7 ,4 8 9 .3
4 ,9 5 6 .7
2 0 .1 4 0 .2
1 3 ,6 3 6 .9
LBA
1 5 ,4 4 8 .9
1 2 ,7 7 1 .5
9 ,2 9 8 .3
4 1 .8 4 8 .2
1 9 ,8 4 1 .7
MyA
BLEA
8 3 2 .1
3 0 ,2 8 2 .7 .
. 3 ,3 6 4 .7
6 0 ,4 2 0 .6
2 3 ,7 2 5 .0
5 4 ,3 7 8 .5
3 ,3 6 4 .7 .
1 ,7 0 0 .5
3 7 ,3 8 6 .0
2 4 ,2 0 7 .4
'
I
■ 'i
—2 6 —
\
2 -l(f);
22 H ours o f l i g h t
1 st
tra n s fe r
2nd
tra n s fe r
3 rd
tra n s fe r
4 th
tra n s fe r.
a v e ra g e
( s p o r e s /m l)
V8
2 5 ,2 1 7 .5
2 0 ,0 6 9 .8
2 0 ,6 2 2 .6
1 1 ,5 7 7 .6
1 9 ,3 7 1 .9
LBA
1 4 ,7 2 5 .3
6 ,6 2 0 .9
1 0 ,8 5 4 .0
1 0 ,6 1 2 .8
1 0 ,7 0 3 .3
MyA
2 ,1 7 0 .8
1 2 ,3 0 1 .2
2 0 ,8 7 5 .9
3 2 ,3 2 0 .8
1 6 ,9 1 7 .2
6 1 ,6 1 4 .5
6 ,5 1 2 .4
1 6 ,6 4 2 .8
1 1 ,5 7 7 .6
2 4 ,0 8 6 .8
2nd
tra n s fe r
3 rd
tra n s fe r
4th
tra n s fe r
a v e ra g e
( s p o r e s /m l)
1 7 ,1 1 3 .1
1 3 ,2 7 8 .1
3 ,7 3 8 .6
1 2 ,4 8 5 :1
A gar ty p e
BLEA
2 - l ( g ) ; 24 H ours o f l i g h t
A gar ty p e
■1 s t
tra n s fe r
V8
1 5 ,8 1 0 .7
.
. LBA
6 ,9 8 2 .7
5 ,1 7 3 .7
8 ,2 1 2 .9
1 2 ,1 8 0 .6
8 ,1 3 7 .5
MyA •
1 ,1 9 3 .9
1 0 ,4 9 2 .2
17 ,7 2 8 ., 2
' 1 8 ,4 5 1 .8
1 1 ,9 6 6 .5
BLEA
5 ,3 1 8 .5
1 2 ,3 0 1 .2
4 ,0 8 8 .3
1 3 ,0 2 4 .8
8 ,6 8 3 .2 .
-27-
T a b le 2 .2
A v erag e s p o r u l a t i o n
( s p o r e s / m l ) o f P.
p h o to p e rio d .
t&uZA a t e a c h
■
P h o to
p erio d
1st
tra n sfe r
2nd
tra n sfe r
3rd
tro n o fo r
4 th
tro n o fo r
overoitG
8
12
16
.20
22
24
3 ,5 0 0 .4
4 2 ,9 3 2 .6
3 6 ,1 5 2 .9
2 3 ,1 5 5 .2
2 5 ,9 3 2 .0
7 ,3 2 6 .5
6 6 ,2 0 9 .4
1 3 ,8 7 5 .1
8 ,2 5 8 .1
1 3 ,4 7 7 .1
1 1 ,3 7 6 .1
1 1 ,2 7 0 .1
5 5 ,8 1 0 .4
4 ,0 7 0 .3
7 ,6 6 1 .2
4 ,8 3 0 .1
1 7 ,2 4 8 .8
1 0 ,8 2 6 .0
8 0 ,1 9 9 .0
6 3 ,4 0 5 .5
4 7 ,1 8 4 .8
3 9 ,9 4 8 .8
1 6 ,5 2 2 .2
1 1 ,8 4 9 .0
5 1 ,4 2 9 .8
3 1 ,0 7 0 .9
2 4 ,8 1 4 .3
2 0 ,3 5 2 .8
1 7 ,7 6 9 .8
1 0 ,3 1 8 .1
hr
hr
hr
hr
hr
hr
( a p o r e s / m l ) o f P . te A te o n e a c h a g a r
Ou n c a n ' □ K u l t l p l e
Range Toot
p -.O ie e
P = .05*
A
B
BC
CD
CDE
E
A
B
BC
BCD
CD
D
T ab le 2 -3 .
A verage s p o r u l a t i o n
Agar ty p e
let
tra n o fe r-
2 nd
tran sfer
3rd
tran o fer
4 th
tran sfer
average
D u n c a n 's M u ltip le
Range T e s t
P - . 05*
7 ,0 7 3 .2
2 0 ,3 4 5 .2
2 4 ,0 2 3 .5
4 1 ,2 2 4 .4
2 9 ,5 6 7 .1
17;9 8 5 .5
2 1 ,6 7 6 .2
1 3 ,7 4 8 .4
2 0 ,7 1 7 .0
1 7 ,1 8 9 .5
1 7 ,3 7 0 .5
1 1 ,6 9 8 .2
5 8 ,8 5 2 .8
4 0 ,0 9 9 .5
3 5 ,8 7 8 .5
3 7 ,9 0 8 .6
2 9 ,0 5 2 .5
2 3 ,9 0 4 .9
2 4 ,7 3 7 .2
2 6 ,1 4 4 .9
A
A
A
A
MyA
LBA
V8
BLEA
*,
**
T h o se v a l u e s n o t f o l l o w e d by s i m i l a r l e t t e r s d i f f e r s i g n i f i ­
c a n tly a t p r o b a b i l i t y P = .05, o r P = .01, r e s p e c ti v e l y .
T ab le 4.
A n aly sis of V arian ce T e s t.
R e p s (R)
P h o to p e rio d
R x P
A g a r (A)
R xA
P x A
RPA ( E r r o r )
(P)
DF
3
5
15
3
9
15
45
95
.
. SS
1 ,0 0 0 ,1 2 0 .0
1 ,6 3 1 ,0 3 0 .0
2 ,0 2 9 ,0 7 0 .0
3 6 ,7 1 8 .4
6 2 7 ,4 7 5 .0
1 2 9 ,3 2 8 .0
5 5 2 ,8 6 3 .0
6 ,0 0 6 ,6 1 0 .0
+ S i g n i f i c a n t a t P = . 01
t
N o n - s i g n i f i c a n t a t P = . 05 o r P = . 01
MS
3 3 3 ,3 7 4 .0
3 2 6 ,2 0 7 .0
1 3 5 ,2 7 1 .0
1 2 ,2 3 9 .5
6 9 ,7 1 9 .5
8 ,2 6 1 .8 4
1 2 ,2 8 5 .9
F v alu e
2 7 .1 3 5 +
2 6 .5 5 1 +
1 1 .0 1 0 +
0 .9 9 6 +
5 .6 7 5 +
0.7 0 2 +
--- +
ty p e.
C h a p te r 3
DETERMINATION OF DIFFERENT VIRULENCE TYPES OF
? yA.&nopkoM. te A z i
I n t h e s p r i n g o f 1 9 7 7 , when t e s t i n g o f b a rle y x v a r i e t i e s f o r t h e i r
r e a c t i o n t o n e t b l o t c h was f i r s t i n i t i a t e d ,
of
VyA-ZYlQpkofux t.zA.zt> w e re a v a i l a b l e .
sev en d i f f e r e n t i s o l a t e s
F o u r o f t h e s e i s o l a t e s w ere from
M ontana an d t h r e e h ad b e e n c o l l e c t e d i n t h e M id d le E a s t .
By t h e summer
o f 1 9 7 7 , t w e n t y - s i x i s o l a t e s w e re a v a i l a b l e , f i f t e e n o r i g i n a t i n g i n t h e
M id d le E a s t and e l e v e n fro m v a r i o u s p a r t s o f M o n tana.
I t w as p o s s i b l e t o t e s t a l i m i t e d num ber o f v a r i e t i e s t o a l l
t w e n t y - s i x i s o l a t e s , b u t when a s c r e e n i n g t e s t was s e t up t o s c r e e n
l a r g e numbers o f b a r l e y l i n e s t o P.
i t n e c e s s a r y t o u s e fe w e r i s o l a t e s .
tzA.Z6f l i m i t s on s p a c e and tim e made
To i n s u r e t h a t t h e re d u c e d num ber
o f i s o l a t e s w ould b e r e p r e s e n t a t i v e o f t h e e n t i r e c o l l e c t i o n , th e
c o l l e c t i o n was s e p a r a t e d i n t o d i f f e r e n t v i r u l e n c e t y p e s .
M a t e r i a l s and M ethods
The t w e n t y - s i x i s o l a t e s w e re s e p a r a t e d i n t o d i f f e r e n t v i r u l e n c e
g ro u p s b a s e d on t h e d i f f e r e n t i a l r e a c t i o n s o f f i f t e e n b a r l e y v a r i e t i e s
w h ic h h ad b e e n t e s t e d t o t h e i s o l a t e s d u r in g t h e summer o f 1977.
The v a r i e t i e s w e re grow n i n m e t a l f l a t s , 1 4 " x l0 " x 3 " , w ith tw e lv e
v a r i e t i e s p la n te d p e r f l a t .
Ten s e e d s o f e a c h v a r i e t y w e re p l a n t e d i n
s i x row s a c r o s s t h e w id th o f t h e f l a t , w i t h two v a r i e t i e s p e r row .
p l a n t s w e re grow n i n a g r o w t h .cham ber w i t h a 150 /2 4 °C d a r k / l i g h t
t e m p e r a t u r e , and a 12 h o u r p h o t o p e r i o d .
The
-2 9 -
The i s o l a t e s o f P . -te/L&4 w e re grow n on V 8 - j u ic e a g a r , i n a n i n c u ­
b a t i o n cham ber w i t h a t e m p e r a t u r e o f 1 7 -1 8 °C and a 12 h o u r p h o t o p e r i o d .
The i s o l a t e s w e re s u b c u l t u r e d u t i l i z i n g t h e m ass s p o r e t r a n s f e r m eth o d
m e n tio n e d p r e v i o u s l y .
I s o l a t e s t o b e u s e d a s i n p c u l a w e re t r a n s f e r r e d
on t h e same d a y t h e b a r l e y t o b e i n o c u l a t e d was p l a n t e d .
The b a r l e y
w as t h e n i n o c u l a t e d s e v e n d a y s l a t e r w i t h t h e s e v e n d a y o ld c u l t u r e s .
The in o c u lu m c o n s i s t e d o f a s u s p e n s i o n o f c o n i d i a a n d some m y c e l i a l
fra g m e n ts .
As a s u r f a c t a n t , a s o l u t i o n o f 1% Tween 20 a t a p p r o x i ­
m a te ly '0 .1 ml o f s u r f a c t a n t , t o 100 m l o f in o c u lu m (0.1% ) was u s e d .
The in o c u lu m was a p p l i e d u s in g a n a to m iz e r d r i v e n by c o m p re s se d a i r .
A p p ro x im a te ly 1 5 -1 8 m l o f in o c u lu m w e re u s e d p e r f l a t .
o f 10
.
A minimum
s p o r e s / m l seem ed n e c e s s a r y t o o b t a i n a d e q u a te i n f e c t i o n .
3
S p o re c o n c e n t r a t i o n s o f 2 0 -3 0 x 10
o b ta in .
s p o r e s / m l w e re n o t d i f f i c u l t t o .
No s t a n d a r d i z a t i o n o f t h e s p o r e c o n c e n t r a t i o n was a tt e m p t e d .
w i t h c o n c e n t r a t i o n s a p p r o a c h in g 8 0 -9 0 x 10
3
s p o re s /m l u sed in th e
in o c u la tio n s .
I n o c u l a t e d p l a n t s w e re in c u b a t e d i n a dew cham ber a t 100% r e l a t i v e
/
h u m id ity i n d a r k n e s s f o r 24 h o u r s .
The t e m p e r a t u r e o f t h e w a te r b a t h
was 35°C an d t h e w a l l t e m p e r a t u r e o f 7°C .
The r e s u l t i n g a i r te m p e ra ­
t u r e was 2 4 -2 7 °C .
R e a d in g s on p l a n t i n f e c t i o n w e re made s e v e n d a y s a f t e r i n o c u l a t i o n .
R e a c tio n t y p e s w e re b a s e d on a s c a l e o f 0 - 4 :
0:
no o b s e r v a b l e i n f e c t i o n
-3 0 -
1:
p i n - p o i n t t o v e r y s l i g h t l y e l o n g a t e d . l e s i o n s • ( 1 - 2 mm) w ith no
o b s e rv a b le c h lo r o s is
2:
s l i g h t l y e lo n g a t e d l e s i o n s , w i t h no n e t t i n g sym ptom s, l i m i t e d
am o u n ts o f c h l o r o s i s
3:
e lo n g a t e d l e s i o n s fo rm in g n e t t i n g sym ptom s, e a s i l y o b s e r v a b l e
c h l o r o s i s , no n e c r o s i s
4:
w e l l d e v e lo p e d , n e t t e d l e s i o n s , w i t h e x t e n s i v e c h l o r o s i s and
n e c ro s is o f le a f tis s u e
The i s o l a t e s w e re t h e n g r o u p e d , b a s e d on t h e s i m i l a r i t i e s arid
d i f f e r e n c e s o f t h e r e a c t i o n s o f t h e b a r l e y v a r i e t i e s and C. I . n u m b e rs.
The i s o l a t e s an d t h e i r o r i g i n a r e l i s t e d
i n T a b le 3 - 1 .
v a r ie tie s u tiliz e d as d if f e r e n tia ls a re lis te d
The b a r l e y
i n T a b le 3 - 2 .
R e s u lts and D is c u s s io n
The M id d le E a s t e r n i s o l a t e s w e re s e p a r a t e d fro m t h e M ontana i s o ­
la te s ,
s i n c e t h e tw o .g r o u p s a s a w h o le p ro d u c e d d i f f e r e n t r e a c t i o n s on
se v era l v a r ie tie s .
F o r e x a m p le , S h a b e t , F i r l b e c k s I I I , B e t z e s , and
I n g r i d w e re s u s c e p t i b l e t o a l l M ontana i s o l a t e s , y e t c o n ta i n e d r e s i s t a n c e
t o s e v e r a l M id d le E a s t e r n i s o l a t e s .
C . I . 7 5 8 4 , C . I . 9776 and S t e p to e
w e re r e s i s t a n t t o a l l M ontana i s o l a t e s , y e t w e re s u s c e p t i b l e to some
M id d le E a s t e r n i s o l a t e s . ,
B e c a u se o f t h e n o n d i s c r ! m i n a to r y r e a c t i o n s of.
t h e s e v a r i e t i e s a n d l i n e s t o t h e M ontana i s o l a t e s , t h e y w e re o f l i t t l e
use as d i f f e r e n t i a l s .
H en ce, i t was n e c e s s a r y t o u t i l i z e o t h e r v a r i e t i e s
—31 —
i n o r d e r t o d e te r m in e v i r u l e n c e t y p e s o f t h e M ontana i s o l a t e s .
T a b le 3 -3 show s t h e M id d le E a s t e r n i s o l a t e s g ro u p e d i n t o t h e i r
r e s p e c t i v e v i r u l e n c e t y p e s , b a s e d on t h e r e a c t i o n s o f f o u r t e e n b a r l e y
lin e s .
V i r u le n c e t y p e A c o n t a i n s f i v e i s o l a t e s , t h e o t h e r t y p e s c o n t a i n
fro m o n e t o t h r e e i s o l a t e s .
The r e a c t i o n s o f t h p s e v a r i e t i e s and l i n e s
w h ic h a r e m o st u s e f u l i n s e p a r a t i n g t h e i s o l a t e s i n t o t h e d i f f e r e n t
v ir u le n c e ty p e s a r e c i r c l e d .
F o r e x a m p le , C . I . 9776 i s s u s c e p t i b l e
t o t y p e B, w h i l e S h a b e t , B e tz e s an d I n g r i d a r e a l l r e s i s t a n t .
Type D
i s t h e o n ly v i r u l e n c e ty p e t o w h ic h M o n a -A riv a t i s r e s i s t a n t .
B oth
C . I . 7584 a n d T if a n g a r e s u s c e p t i b l e t o ty p e E, w h i l e ty p e F i s t h e
o n ly v i r u l e n c e ty p e t o w h ic h C . I . 7 5 8 4 , C . I . 9776 and S t e p to e a r e a l l
s u s c e p t i b l e a n d b o t h S h a b e t an d I n g r i d a r e r e s i s t a n t .
A rim ont i s r e ­
s i s t a n t o n ly t o v i r u l e n c e t y p e G.
T a b le 3 -4 show s t h e v i r u l e n c e t y p e s o f t h e M ontana i s o l a t e s o f
P.
teA-QJ), b a s e d on t h e r e a c t i o n s o f e i g h t b a r l e y v a r i e t i e s and l i n e s .
H ere a g a i n , t h o s e l i n e s an d v a r i e t i e s m o st u s e f u l i n s e p a r a t i n g t h e
.
d i f f e r e n t v ir u le n c e ty p e s a re c i r c l e d .
T if a n g i s s u s c e p t i b l e o n ly to
ty p e C.
C . I . 9819 e x h i b i t s ty p e 4 sym ptom s o n ly t o t h o s e i s o l a t e s i n
ty p e D.
B o th Lud an d P i r o l i n e a r e i n t e r m e d i a t e i n r e a c t i o n to ty p e E,
w h i l e Lud i s r e s i s t a n t t o i n t e r m e d i a t e i n r e a c t i o n t o ty p e B and P i r o l i n e
is s u s c e p tib le .
U sin g d i f f e r e n t i a l v a r i e t i e s a d ic h o to m o u s k e y was s e t up w i t h
w h ic h i t was p o s s i b l e t o d i s t i n g u i s h t h e v i r u l e n c e t y p e s o f t h e M id d le
-
E a s te rn i s o l a t e s
( T a b le 3—5 ) .
3 2
-
A l l s e v e n v i r u l e n c e t y p e s c o u ld b e s e p a r ­
a t e d u s i n g f i v e d i f f e r e n t i a l b a r l e y l i n e s ; C . I . 9 7 7 6 , . C . I . 7584, A r im o n t,
M o n a -A riv a t a n d B e t z e s .
A n o th e r d ic h o to m o u s k e y , u t i l i z i n g a d i f f e r e n t s e t o f d i f f e r e n t i a l s ,
was s e t up f o r d e te r m i n in g t h e v i r u l e n c e t y p e s o f t h e M ontana i s o l a t e s
t.Zh.QA ( T a b le 3 - 5 ) .
o f P.
The f i v e M ontana v i r u l e n c e t y p e s c o u ld b e
d i s t i n g u i s h e d u s in g f o u r d i f f e r e n t i a l b a r l e y l i n e s ; L u d , P i r o l i n e ,
T if a n g a n d C . I . 9 8 19.
The s e p a r a t i o n o f t h e i s o l a t e s i n t o v i r u l e n c e t y p e s w as done p r i ­
m a rily to o b ta in i s o l a t e s r e p r e s e n t a ti v e o f th e e n t i r e c o ll e c t i o n .
was d e te r m in e d t h a t n i n e i s o l a t e s o f P .
in a s c re e n in g t e s t .
It
c o u ld b e e f f i c i e n t l y u s e d
N in e i s o l a t e s w e re t h e r e f o r e c h o s e n , e a c h fro m a
d i f f e r e n t v iru le n c e ty p e .
B e c a u s e t h e i s o l a t e s h ad b e e n s e p a r a t e d i n t o
m ore t h a n n i n e v i r u l e n c e t y p e s , t h e i s o l a t e s w e re c h o s e n fro m t h e n i n e
m o st v i r u l e n t g r o u p s .
T h e se g ro u p s a r e i n d i c a t e d i n T a b le s 3 -5 a n d 3 -6
by a s t e r i k s .
T h is w ork i s n o t v ie w e d a s a f i n a l c o n c lu s i o n i n d e a l i n g w i t h t h e
v ir u le n c e ty p e s o f .th e s e i s o l a t e s .
I t i s u s e f u l a s a m eth o d f o r s e l e c t ­
in g r e p r e s e n t a t i v e i s o l a t e s fro m a l a r g e c o l l e c t i o n f o r u s e i n s c r e e n i n g
te s ts .
K now ledge o f t h e d i f f e r e n t v i r u l e n c e t y p e s o c c u r r i n g i n an o r ­
g a n ism i s v a l u a b l e i n t h a t i t p r o v i d e s a t o o l by w h ic h b r o a d b a s e d
so u rc e s o f r e s i s ta n c e can be s e le c te d .
-
T a b le 3 - 1 .
3 3
-
I s o l a t e s o f P . £.QJiQJt> I n c lu d e d i n t h e c o l l e c t i o n and th e
p la c e o f o r ig in o f each .
Is o la te
O r i g in
Pt 8
T u n i s ia
P t 8 o rig
P t 10
"
L ebanon
P t I O o rig
"
P t T -I
T u n i s ia
T u n is I
"
T u n is 75
Mor I
.
"
M orocco
Mor 14
"
Mor 15
"
Mor 18
Pt 6
T u rk e y
ELS 7 7 - 5
M orocco
ELS 7 7 -6
Jo rd a n
■ ELS 7 7 -9
Egypt
Mt 7 7 -1
F a i r f i e l d , M t.
Mt 7 7 -2
"
Mt 7 7 -3
F o rt
Mt 7 7 -4
B e n to n , M t.
' C r e s t o n , M t.
Mt 7 7 -5 1
S id n e y , M t.
Mt 7 7 -6
M o c c a s s in , M t.
Mt 7 7 -7
H u n tle y , .Mt.
Pt S
P t S -2
S id n e y , M t.
"
Pt R
R u d y a rd , M t.
Pt B
B a k e r , M t.
-3 4 -
T a b le 3 - .
V a r i e t i e s and C . I . l i n e s u s e d i n d e te r m i n in g t h e d i f f e r e n t
v i r u l e n c e t y p e s o f P.
U n ita n
T if a n g
S t e p to e
C . I . 5791
Shabet
C . I . 9819
Dekap
C . I . 9776
X n g tid
C . I . 7584
B e tz e s
A rim o n t
F irlb e c k s I I I
M o n a -A riv a t
H o rsfo rd
. b a rk e r
Lud
P iro lin e
P a llis e r
H ypana
Table 3 - 3 .
Virulence types o f the Middle East isolates o f P. tHA<US>
V ariety or C .I.
Nu m b er
Iso la te 1
7584
9776
9819
5791
T ifa n g
S tep to e
C n itan
D ek ap
F irlb e c k s
III
Shabet
B e tz e s
In g rid
A riaont
M on aA riv at
Type A
Pt 8
Pt S o rig *
P t 10
P t IO o rig
P t T -I
1 .2
1 .2
1 .2
2 .3 .1
1 .2
I
1 .2
1 .2
2 .1
2 .3
2 ,3
2 ,1
3 ,2
2 .1
2 .1
2 .1 ,3
2 .1
3 ,2 ,4
1 .2
2 .1
1 ,2
2
1 .2
1 .2
1 .2
1 .2
2
I
1 .2
2 .1 .3
2 .1
1 .2
2 .1
1 .2
4
4
4 .3
4
4 ,3
4 .3
3 .4
3 .4
3 ,4
4 .3
4 .3
4 ,3
4
4 .3
4
4
4,3
4
4.3
4
4
4.3
4
4.3
4.3
4.3
4
4
4.3
4.3
4 .3
3 ,4
4 .3
2 .3 ,4
3.2
1 .2
2 .1
1 .2
1 .2
2 .1
1 .3 .2
2 .1 .3
2 .1
2 .1
2
4 .3
4 .3
3 .2 .4
2 .4 .3
2 .3 .1
2 .3
1 . 2.3
1 . 2.3
1.2
1.2
4.3
4,3
4 .3
4
1.0
Type B
Mor 1 5 *
Mor 18
2 .3
1 .2
Type C
H S 77-6*
ELS 7 7 - 9
1 .2
2 .1
2 .1
2 .3
1 .3 ,2
2 .1 .3
1 .3 .2
1 .2
1 .2
2 .1
3 .2
1 .2
3 .2
3 ,2 .4
3 .4
3 .4
3
2 .3
3 .2 .4
—
1 . 3,2
2.1
2.1
2. 1.3
4,3
3. 2,4
3 .4 .2
3 ,2
Type D
T a la
2 .3 .1
2 .1
2 .1
1 .2
1 .3 .2
2 .1
2 ,1
4 .3
2 .3
3 .4
3 . 4.2
1.2
4.3
12,1,31
Type E
Mor I *
EU
1 .2
2 .1
I
O
2 .3
2 .1
4
4 .3
4 .3
3.2
4.3
4
4
Type F
Mor 1 4 *
* .3
4 .3
2 .1
2 .1 .3
3 .2
i3 .4 ,2 |
3 .2
4
4
3 , 2.4
B
* ,3
4
Type C
P t6
ELS 7 7 - 5
T u n i s 75
3 .4
2
3 .2
1 .2
2 .1
2 .1
2 .3
3 .2
3 .2
1 .2
2 .1
2 ,1
3 .2 .4
2 .3
2 .3
2 .3
2 .3
2 .3
1 .2
2 .3
1 ,2
3
3 ,4 ,2
3 .2
2
2 .3 .1
2 .3
3. 2.4
3.2
2.1
2.1
2.3
2.1
2 ,1 .3
2 .1
1 .2
3 .4
3.4
3 ,2
1.
2.
_______
2 , 1.3
2.3
2.1
T h o s e i s o l a t e s f o l l o w e d b y a n a s t e r i k w e r e u s e d I n t h e s c r e e n i n g o f b a r l e y l i n e s f o r r e s i s t a n c e t o P . -teAeA ( C h a p t e r 4 ) .
T hose r e a c t i o n s c i r c l e d w ere e s p e c i a l l y u s e f u l i n d e t e r m i n in g t h e d i f f e r e n t v i r u l e n c e t y p e s o f th e M iddle E a s t i s o l a t e s
o f P. t l A U .
T a b le 3 - 4 .
V ir u le n c e t y p e s o f t h e M ontana i s o l a t e s o f P .
teAZA
V a r i e t y o r C . I . Number
Is o la te 1
C . I . 9819
C . I . 5791
T if a n g
U n ita n
b a rk e r
Lud
Type A
P t R*
Mt 7 7 -2
2 ,1
2 ,1 ,3
1 ,2
1 ,2
3 ,2
1 ,3
2 ,1
2 ,1
4 ,3
3 ,4
4
4 ,3
Type B
Pt S
P t S -2
P t B*
2 ,3 ,1
1 ,2
2 ,1 ,3
2 ,1
2 ,1 ,3
2 ,1
3 ,2
1 ,2
1 ,2
2 ,3
2 ,1
2 ,1
4 ,3
3 ,4
3 ,2 ,4
ITITlf
2 ,1 ,3
3 ,2
3 ,4
4 .3
3 .4
4
4
4
Type C
Mt 7 7 -1
Mt 7 7 -5 1 *
1 ,2
2 ,1
2 ,3
2 ,1
pn
LU
2 ,3
2 ,1
3 ,4
4 ,3
3 ,2 ,4
3 ,4 ,2
3 ,4
4
4 ,3
4
Type D
Mt 7 7 -3 *
Mt 7 7 -4
2 ,4 ,3
3 ,2 ,4
3 ,4
2 ,3
i
—
2 ,1
2 ,1
2 ,3 ,4
2 ,3
3 ,2 ,4
3 ,4
2 ,3
3 ,4
4
4 ,3 ,2
2 ,3
2 ,3
2 ,3
2 ,3 ,1
1 ,2
3
2 ,3
3 ,2
3 ,2
3
2 .3
2 .3
1.
2.
4 ,3
4
2 ,3
2 ,3
Dekap
4
4
4
4 ,3
T hose i s o l a t e s f o llo w e d by a n a s t e r i k w e re u s e d i n t h e s c r e e n i n g o f b a r l e y l i n e s f o r r e ­
s i s t a n c e t o P. £eAU ( C h a p te r 4 ) .
T h o se r e a c t i o n s c i r c l e d w e re e s p e c i a l l y u s e f u l i n d e te r m i n in g t h e d i f f e r e n t v i r u l e n c e
t y p e s o f t h e M ontana i s o l a t e s o f P . -teAeA.
-3 6 -
Type E
Mt 7 7 -6
Mt 7 7 -7
P iro lin e
-
T a b le 3 - 5 .
,
3 7
-
Key f o r I d e n t i f y i n g t h e v i r u l e n c e t y p e s o f t h e M id d le
E a s te rn i s o l a t e s .
V ir u le n c e ty p e
H o st R e a c tio n
C . I . 9776 s u s c e p t i b l e
C . I . 7584 s u s c e p t i b l e . . .................................. ....................... ...
. . .T y p e F
C . I . 7584 r e s i s t a n t . ................................................................... . . . .T ype B
C . I . 9776 r e s i s t a n t
C . I . 7584 s u s c e p t i b l e .
C . I . 7584 r e s i s t a n t
................................................................................ Type E
A rim o n t r e s i s t a n t ......................................
A rim orit s u s c e p t i b l e
M o n a -A riv a t r e s i s t a n t .......................
M o n a -A riv a t s u s c e p t i b l e
Type G
Type D
B e tz e s s u s c e p t i b l e ......................................................... Type A.
B e tz e s r e s i s t a n t ...........................................
Type C
-
■T a b le 3 - 6 .
38
-
Key f o r i d e n t i f y i n g t h e v i r u l e n c e ty p e s , o f t h e M ontana i s o l a t e s ;
T
H o st R e a c tio n
V i r u le n c e ty p e
Lud r e s i s t a n t
P iro lin e r e s is ta n t. .
. . . ; . . . . ,
. . . . . . .T y p e E
P i r o l i n e s u s c e p t i b l e . . . ............................. .... ............................................T y p e B
Lud s u s c e p t i b l e
T if a n g s u s c e p t i b l e .
T if a n g r e s i s t a n t '
.............................
................... ....
C . I . 9819 s u s c e p t i b l e . .
................................................ ....
C . I . 9819 r e s i s t a n t . .................................. ....................... ....
.T y p e C
.T y p e D
.T y p e A
C h a p te r 4
SCREENING OF BARLEY LINES FOR RESISTANCE TO Vy/ienophoJUL .t e / l U
The virulence types previously designated for isolates of PijAerio-
pkoACL te A e 6 were utilized in this experiment to screen barley lines and
varieties for resistance to net blotch.
It was anticipated that the
testing of lines ,against nine separate isolates, each representing a
different virulence type, would result in the discovery of lines which
contain resistance to a wide range of virulence types.
Materials and Methods
One h u n d re d an d f o r t y - s e v e n l i n e s o f b a r l e y w e re s c r e e n e d i n t h i s
te s t.
T h e se l i n e s c o n s i s t e d o f t h r e e m a jo r g r o u p s .
The l a r g e s t g ro u p
i n c l u d e d 78 l i n e s p r e v i o u s l y fo u n d t o b e r e s i s t a n t t o M oroccan i s o l a t e s
o f P.
teA U ( C a d d e l and W ilc o x s o n , 1 9 7 5 ).
A n o th e r g ro u p o f f o r t y l i n e s
h ad p r e v i o u s l y b e e n fo u n d to b e r e s i s t a n t i n C anada t o N o rth A m erican
i s o l a t e s o f P.
teAe6 ( B uchannon and M cD onald, 1 9 6 5 ).
The t h i r d g ro u p
c o n s i s t e d o f 23 v a r i e t i e s c o m m e rc ia lly grow n i n t h e s t a t e o f M ontana and
n o t p r e v i o u s l y s c r e e n e d f o r r e s i s t a n c e t o P. -teAeA.
S eed o f t h e s e l i n e s
was obtained either from seed stocks on hand or from Dr. J. C. Craddock,
'i
Beltsville, Md.
The lines were planted in metal flats and grown under conditions
previously described.
Eleven lines plus the susceptible check, Dekap,
were planted in each flat.
A r e p r e s e n t a t i v e i s o l a t e was c h o s e n fro m e a c h o f t h e n i n e v i r u l e n c e
-40-
ty p e s in d ic a te d in th e p re v io u s e x p e rim e n t.
T h ese i s o l a t e s w e re :
P t R (R u d y a rd , M t.)
Mor I
P t B ( B a k e r , M t.)
Mor 14 (M orocco)
Mt 7 7 -3 ( F o r t B e n to n , M t.)
Mor 18 (M orocco)
Mt 7 7 -5 1 ( S id n e y , M t.)
ELS. 7 7 -6 ( J o r d a n )
P t S o r ig
(M orocco)
(T u n is ia )
The i s o l a t e s w e re c u l t u r e d i n t h e same m anner d e s c r i b e d p r e v i o u s l y ,
e x c e p t t h a t a p h o t o p e r i o d o f 8 h r . , r a t h e r th a n 12 h r . , was u s e d .
In ­
o c u l a t i o n p r o c e d u r e s a n d r e c o r d i n g o f t h e d i s e a s e r e a c t i o n s w e re a l s o
p e rfo rm e d a s p r e v i o u s l y d e s c r i b e d .
The d i s e a s e r e a c t i o n s o f t h e b a r l e y l i n e s w e re s e p a r a t e d i n t o t h r e e
g ro u p s:
R e s is ta n t:
L in e s e x h i b i t i n g t y p e I o r ty p e 2 r e a c t i o n s , o r a
c o m b in a tio n o f t y p e I and ty p e 2 r e a c t i o n s .
In te rm e d ia te :
L in e s e x h i b i t i n g a c o m b in a tio n o f ty p e 2 and
ty p e 3 r e d a c tio n s .
S u s c e p tib le :
L in e s e x h i b i t i n g ty p e 3 o r ty p e 4 r e a c t i o n s , o r
a c o m b in a tio n o f ty p e 3 and ty p e 4 r e a c t i o n s .
R e s u l t s an d D i s c u s s i o n
The r e s u l t s o f t h e s c r e e n i n g t e s t a r e shown i n T a b le s 4 -1 and 4 - 2 .
The b a r l e y l i n e s a r e g ro u p e d i n two d i f f e r e n t way's.
I n T a b le 4 - 1 , t h e
l i n e s a r e g ro u p e d a c c o r d in g t o t h e num ber o f v i r u l e n c e t y p e s a g a i n s t
w h ic h t h e y a r e r e s i s t a n t .
I n T a b le 4 - 2 , th e y a r e g ro u p e d a c c o r d in g t o
-41-
t h e num ber o f v i r u l e n c e t y p e s a g a i n s t w h ic h th e y e x h i b i t a r e s i s t a n t o r
a n i n t e r m e d i a t e ty p e o f r e a c t i o n .
Of t h e 147 l i n e s t e s t e d , o n ly t h r e e w e re r e s i s t a n t t o a l l n in e
v i r u l e n c e t y p e s ( T a b le 4 - 1 ) .
th e n in e v iru le n c e ty p e s .
F o u r m ore l i n e s w e re r e s i s t a n t t o e i g h t o f
T h i r t y l i n e s , 20.4% o f t h e t o t a l , w e re r e - :
s i s t a n t t o s i x o r m ore v i r u l e n c e t y p e s .
C o n s id e r in g b o t h r e s i s t a n t
an d i n t e r m e d i a t e r e a c t i o n s i n o n e c l a s s , n i n e l i n e s w e re e f f e c t i v e
a g a in s t a l l n in e v ir u le n c e ty p e s
( T a b le 4 - 2 ) .
An a d d i t i o n a l tw e n ty
l i n e s show ed r e s i s t a n t o r i n t e r m e d i a t e r e a c t i o n s t o e i g h t v i r u l e n c e
ty p e s.
As s t a t e d e a r l i e r , t h e l i n e s i n v o lv e d i n t h i s s c r e e n i n g t e s t
c o n s i s t m a in ly o f t h r e e m a jo r g r o u p s .
Of t h o s e l i n e s fo u n d t o b e r e ­
s i s t a n t t o N o r th A m e ric an i s o l a t e s o f P.
teAZA, s e v e n t e e n l i n e s , 42.5% .
o f t h e t o t a l , w e re r e s i s t a n t t o s i x o r m ore v i r u l e n c e t y p e s (T a b le 4 - 3 ) .
Of t h o s e l i n e s p r e v i o u s l y fo u n d r e s i s t a n t t o M oroccan i s o l a t e s o f
P. teAZ6, 10 l i n e s , 12.8% o f th e t o t a l , w e re r e s i s t a n t t o a t l e a s t s i x .
v iru le n c e ty p e s .
O nly two o f t h e 23 c o m m e rc ia l v a r i e t i e s w ere r e s i s ­
t a n t t o s i x o r m ore v i r u l e n c e t y p e s .
Tw enty o f t h e t w e n t y - t h r e e , v a r i ­
e t i e s w e re r e s i s t a n t t o t h r e e o r fe w e r o f t h e v i r u l e n c e t y p e s .
The l i n e s r e p o r t e d t o b e r e s i s t a n t i n C anada h a d b e e n t e s t e d i n
t h e g r e e n h o u s e t o i s o l a t e s fro m C a n a d a , M exico and t h e U .S .
The r e ­
s i s t a n c e fo u n d t o b e e f f e c t i v e a g a i n s t t h o s e i s o l a t e s a p p e a r e d to a l s o
b e r e l a t i v e l y e f f e c t i v e a g a i n s t t h e i s o l a t e s u s e d i n t h i s s c r e e n in g t e s t
—42—
T h irty -o n e l i n e s ,
77.5% o f t h e t o t a l , show ed r e s i s t a n t o r i n t e r m e d i a t e
r e a c t i o n s t o a t l e a s t s i x . o f t h e v i r u l e n c e ty p e s ( T a b le 4 - 4 ) .
I n M orocco, n a t u r a l i n f e c t i o n i n t h e f i e l d was r e l i e d upon t o p r o ­
d u c e r e a d a b l e sym ptom s on t h e p l a n t s .
The r e s i s t a n c e fo u n d e f f e c t i v e in,
M orocco was l e s s e f f e c t i v e a g a i n s t t h e w id e r r a n g e o f v i r u l e n c e ty p e s
u sed in t h i s t e s t .
T w n e ty -n in e l i n e s , 37.2% o f t h e t o t a l , w e re r e ­
s i s t a n t o r i n t e r m e d i a t e i n r e a c t i o n t o s i x o r m ore v i r u l e n c e t y p e s .
.
O v e r a ll, th e s e l i n e s a r e r e l a t i v e l y l e s s e f f e c t i v e th a n th o s e te s te d
i n C an ad a, b u t a r e c o n s i d e r a b l y m ore r e s i s t a n t t h a n t h e c o m m e rc ia l
v a r i e t i e s w h ic h h a d n o t p r e v i o u s l y b e e n s c r e e n e d f o r n e t b l o t c h r e ­
s is ta n c e
( T a b le 4 - 4 ) .
T h e se r e s u l t s i n d i c a t e th e v a l u e o f u s in g a w id e
r a n g e o f v i r u l e n c e t y p e s when s c r e e n i n g f o r d i s e a s e r e s i s t a n c e .
The barley lines exhibiting resistant or intermediate reactions,
to eight or nine virulence types were crossed into a male sterile
facilitated recurrent selection population being developed for.net
blotch resistance.
It is anticipated that these lines will provide a .
source of broad-based resistance effective against a wide range of
virulence types of this organism.
/
-43-
T a b le 4 - 1 .
R e la tiv e r e s i s t a n c e o f v a r io u s b a rle y l i n e s to d i f f e r e n t
i s o l a t e s o f VtjH.<mopkoha toAdA.
B a r le y l i n e
I>t R
Pt B
Mt
7 7 -3
I s o la te s
Mt
Pt
7 7 -5 1 S b r ig
Mor I
Mor 14
Mor 18
ELS
7 7 -6
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
I
R
R
R
R
R
R .
R
R
I
R
R
R
S
R
R
R
R
I
R
R
S
R
R
R
R
R
S
R
R
R
R
R
R
R
R,
R
S
R
R
I
R
S
I
R
S
R
R
L in e s r e s i s t a n t t o n i n e v i r u l e n c e t y p e s
C . I . 1615 (C)
C . I . 5845 (C)
C . I . 9768 (C)
R
R
R
R
R
R
R
R
R
R
■R
R
L in e s r e s i s t a n t t o e i g h t v i r u l e n c e t y p e s
C .I .
C .I .
C .I .
C .I .
5791
6388
12821
14023
(C)
(C)
(M)
(C)
R
R
R
S
R
R
R
R
S
S
R
R
R
R
S
R
L in e s r e s i s t a n t t o s e v e n v i r u l e n c e t y p e s
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
4207
5401
6475
7208
7447
9669
9751
9819
(M)
(C)
(C)
(C)
(M)
(M)
(M)
(C)
I
I
R
I
R
S
R
R
R
R
R
R
R
R
S
R
R
R
I
I
R
I
R
S
R
R
R
R
R
R
S
R
L in e s r e s i s t a n t t o s i x v i r u l e n c e ty p e s
C .I .
C .I .
C .I .
C .I .
I)
2235
5276
5298
5404
(C)
(M)
(M)
(C)
R
I
I
I
I
R
R
R
R
R
R
R
I
R
R
R
T h o se l i n e s f o llw e d by (C) w e re t e s t e d t o N o rth A m erican i s o l a t e s ,
t h o s e f o llo w e d by (M) w e re t e s t e d t o M oroccan i s o l a t e s , t h o s e f o l ­
low ed by (M t.) a r e t h e M ontana grow n v a r i e t i e s , t h o s e n o t f o llo w e d
by an y l e t t e r a r e n o t in v o lv e d w i t h an y o f t h e t h r e e m a jo r g r o u p s .
R
■PR
I
iS
-4 4-
T a b le 4 -1
(c o n t.)
Is o la te s
B a r le y l i n e
Pt R
Pt B
Mt
7 7 -3
Mt
7 7 -5 1
L in e s r e s i s t a n t t o s i x v i r u l e n c e ty p e s
C . r . 5822 (C)
C . I . 7504 (C)
C . I . 7584 (C)
C . I . 9776 (C)
C . I . 9825 (C)
C . I . 9827 (M)
C . I . 10379 (M)
C . I . 12860 (M)
S t e p to e (M t.)
T if a n g
U n ita n (Mt .)
I
I
R
R
I
S
S
S
R
I
R
R
R
R
R
I
S
R
R
R
R
R
R
I
R
R
R
R
R
R
R
R
R
'
R
R
S
I
R
R
R
R
R
S
R
Pt
B o rlg
ELS
Mor I
Mor 14
Mor 18
7 7 -6
I
R
.R
S
R
R
R
R
R
R
R
I
S
( c o n t.)
R
R
R
.R
R
R
R
R
R
R
R
.
R
R
S
R
R
I
I
I
I
■S
I
R
R
S'
S
R
R ’
S
I
S
R
I .•
R
R
S
R
R
R
I '
R
I
L in e s r e s i s t a n t t o f i v e v i r u l e n c e ty p e s
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
7272 (C)
7744 (M)
8332 (C)
8333 (C)
9647 (C)
9648 (C)
10903 (M)
11631 (M)
R
S
I
R
S
S
S
I
R
R
R
R
R
R
R
R
R
S
R
R
S
R
R
I
I
R
R
. R
R
R
S
R
I
R
R
R
R
R
R
R
R
R
R
S
I
’ I
R
R
I
I.
S
S
R
I
S
S
R
R
R
R
R
I
R
I
I
R
R
. R
I
R
R
I
S
R
S
S
R
I
S
I
I ■
R
S
I
R
S
S
R
S
I
R
R
R
R
R
I
R
R
R
S
I
R
R
, R
R
I
I
I
S
I
S
I
S
L in e s r e s i s t a n t to f o u r v i r u l e n c e t y p e s
• C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
1064 (M)
4373 (M)
5810 (C)
6496 (M)
9408 (M)
9440 (C)
9505 (C)
9758 (M)
10070 ' (M)
10778 (M)
S
S
R
S
S
I
I
R
S
S
I
S
R
I
S
R
I
S
R
R
I
I
S
I
R
R
R
R
S
S
R
S
I
R
I
R
R
S
S
S
R
S
I
R
S
I
I
-R
R
-4 5 -
T a b le 4 - 1
(cen t).
B a r le y l i n e ____ P t R
Pt B
Mt
7 7 -3
Is o la te s
Mt
Pt
7 7 -5 1 S o r lg
Mor I
Mor 14
Mor 18
ELS
77-^6
I
R
S
R
R
R
■I .
R
R
R
.S
R
R
R
I
S
I
R
R
R
I
R
R
R
R
I
S
S '
R
I
R
R
S
R
R
R
S
I
R
R
R
R .
I
I
I
R
. I
S
S
I
R
S
S
S
I
R
R
I
S
,s
L in e s r e s i s t a n t t o f o u r v i r u l e n c e t y p e s ( c o n t . )
C . I . 10781
C . I . 13244
C . I . 13727
C . I . 14127
C . I . 14265
F r e j a (M t. )
(M)
(M)
(M)
(M)
(M)
S
S
I
I
R
S
R
I
R
•' ■---"
R
S
S
I
R
S
S
S
S
R
S
S
S
S
R
R
I
S
S
S
L in e s r e s i s t a n t t o t h r e e v i r u l e n c e t y p e s
C . I . 1261 (M)
C . I . 3430 (C)
C . I . 4428 (C)
C . I . 4544
C . I . 5196 (M)
C . I . 5199 (M)
C . I . 6868 (M)
C . I . 7296 (M)
C . I . 7297 (C)
C . I . 7324
C . I . 7339 (M)
C . I . 8868 . (M)
C . I . 9214 (C)
C . I . 9215 (M)
C . I . 9263 (C)
C . I . 9567 (M)
C . I . 9698 (M)
C . I . 9741 (M)
C . I . 10075 (M)
C . I . 11977 (M)
C . I . 11978 (M)
C . I . 12875 (M)
C . I . 13262 (M)
C . I . 13749 . (M)
C . I . 14103 (M)
C . I . 14295 (M)
E r b e t (M t. )
S
S
.
•
R
R
I
S
S
S
R
I
R
S
S
I
I
R
R
R
R
S
R
S
S
S
S
S
S
S
I
S
S
S
S
S
I
S
S
S
S
S
R
I
R
R
R
I
S
S
R
I
I
R
R
S
S
S
R
S
R
I
S
S
S
R
R
I
R
I
S
I
S
S
I.
I
I
S
I
S
I
—
S
—
R
R
R
S
R
S
S
S .
S
R
S
R
R
I
I
I
R
S
S
R
S
I
R
S
S
S
I
R
R
R
R
R
R
I
R
S
S
R
R
R
R
I
R
R
S
S
S
I
I
I
R
R
S
S
S
I
S
'
I
S
S
I
I
R
R
R
S
R
R
I
I
'S
I
I
I
I
R
S
S
I
S
S
I
S
R
R
----R
R
S
S
S
S
R.
R .
S
'R
S
I
S
I
R
R
I'
I
:
S
I
I
R
I
R
S
S
S
R
I
S
I
1 . R
S
S
I
S
S
S
R
—4 6—
T a b l e 4^-1 ( c e n t . )
B a r le y l i n e
Mt
7 7 -3
P t R ']? t B
Is o la te s
Mt
Pt
7 7 -5 1 S o r ig
L in e s r e s i s t a n t t o t h r e e v i r u l e n c e t y p e s
I n g r i d (M t.)
K la g e s (M t. )
M anker (M t. )
S
S
S
S
S
I
'
S
S-
S
S
S
S
Mor I
Mor 14
S
I
S
S
S
R
R
R
R
R
S
S
I
R
I
I
R
R
R
R
R
R
R
I
S
I
S
S
S
I
S
S
S
I
R
R
S
R
S
S
S
I
I
S
S
S
S
S
I
I
R
S
I
R
S
R
I
S ’
S
S
S
S
I
S
R
I
R
R
R
I
S
S
I
S
I
I
R
. I
R
S
R
I
R.
S
S
.S
R
R
R
S
R
S
I
I
I
I
I
S
R
S
S
S
I
S
. I
I
S
I
I
S
I
S
ELS
7 7 -6
Mor 18
(c o n t. )
.
R
R .
S
. R
R
R
L in e s r e s i s t a n t t o two v i r u l e n c e t y p e s
C . I . 4638 (C)
C . I . 5108 (C)
C . I . 8270 (C)
C . I . 9584 (C)
C . I . , 9592 (C)
C . I . 9693 (C)
C . I . 9702 (M)
C . I . 9831 (C)
C . I . 9881 (M)
C . I . 10786 (M)
C . I . 11056 (M)
C . I . 11121 (M)
C . I . 11546 (M)
C . I . 11578 (M)
C . I . 12949 (M)
C . I . 13797 (M)
C . I . 14033 (M)
G e o rg ia (M t.)
Lud (M t.)
P i r o l i n e (M t.)
S
S
S
S
S
S
S
I
I
S
S
S
I
I
S'
S
R
S
S
S
I
I
R
R
S
S
I
I
S
S
R
S
R
S
R
S
I
S
R
S
R
S
S
S
S
I
I
I
S
S
S
S
S
R
R
S
S
I
S
R
I
R
I
R
I
I
S
S
S
I
S
S
S
S
S
S
S
S
-
S
I
I
S
S
S
I
I
I '
S
S
S
S
S
R
I
I
I
I
S
L in e s r e s i s t a n t t o one v i r u l e n c e ty p e
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
1197
2216
2330
5057
5172
5376
5809
8952
(M)
(C)
(M)
(M)
(C)
(M)
I
S
S
S
S
S
S
S
I
S
S
S
S
S
R
I
I
I
S
S
S
S
S
I
I
S
S
R
I
S
I
S
R
S
I
S
I
I
I
I
'
.
I
S
S
S
R
R
S
R
-4 7 -
(c e n t.)
B a r le y l i n e ____ P t R
Pt B
Mt
7 7 -3
I s o la te s ■
Mt
Pt
7 7 -5 1 B o rlg
L in e s r e s i s t a n t t o o n e v i r u l e n c e ty p e
C . i ; 9327 (M)
C . I . 9569 (M)
C . I . 9669 (C)
C . I . 10615 (M)
C . I . 10624 (M)
C . I . 10905 (M)
C . I . 12034 (M)
C . I . 12674 (M)
C . I . 12894 (M)
C . I . 14218 (M)
C . I . 14273 (M)
B e tz e s (M t.)
H e c to r (M t.)
H o r s f o r d (M t.)
H ypana (M t.) .
P a l l i s e r (M t.)
S h a b e t (M t. )
I
S
S
S
S
S
S
S
I
S
S
S
S
S
S
S
S
S
S
R
S
I
R
S
S
R
S
S
S
:
s
S
■I
S
S
S
. S
S
S
I
S ■
I
S
■
S
S
S
S
S
S
I
S
S
S
R
S
R
S
S
S■
S
S
S
S
I
R
S
S
S
S
Mor I
Mor 14
Mor 18
ELS
7 7 -6
S
R
S
S
S
I
5S
R
( c o n t.)
R
S
I
S
R
I
S
S
S
I
I
S
S
I
S
I
S
S
I
I
S
S
S
I
S
S
S
. S
S
S
R
S
:
R
S
S
S
S
S
S
• S
S
I
S
S
I
S
S
S
S
S
R
I
S'
H H
T a b le 4 - 1
S
S
S
S
S
S
S
I
R
R
S
S
S
I
S
I
S
S■
L in e s w i t h no r e s i s t a n c e t o an y o f t h e v i r u l e n c e t y p e s
C . I . 4179 (M)
C . I . 5187 (M)
C . I . 7725 (M)
C . I . 9345 (M)
C . I . 9350 (M)
C . I . 10132 (M)
C . I . 10364 (M)
C . I . 10367 (M)
C . I . 14093 (M)
C . I . 14354 (M)
A rim o n t (M t.)
Compana (M t. )
Dekap (M t. )
F irlb e c k s I I I
K a r l (M t.)
S
S
S
S
S
S
S
S
I
S
S .
S
S
S
S
S
S
I
S
•S
. S
S
S
S
I
S ■ ■I
S
S
I
S
---—
S
—
S
S
S
S
S
S
S
S
S
S
S
S .
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S
I
S
I
I
S
S
■I
I
I
S
S
S
S
S
I
S
I
I
I
S
I
I
S
S
S'
S
S
S
S
.S
S
S
S
S
S
S
S
S
S
S
S
\ s
S
I
S
S
S
S '
S
S
S
■S
- S
.
S
S
S
S
S.
I
S
I
S
■S
S
S
I
S
S
S
S
S
S
S
S
-4 8 -
T a b le 4 - 1 ( c e n t . )
Isolates
B a r le y l i n e
Pt R
Pt B
Mt
7 7 -3
Mt
7 7 -5 1
■
Pt
S o r ig
Mor I
L in e s w i t h no r e s i s t a n c e to an y o f t h e v i r u l e n c e ty p e s
D a rk e r (M t. )
M o n a -A riv a t
V an g u ard (M t. )
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
I
S
S
Mor 14
Mor 18
-E L S
7 7 -6
I
S
I
■" S
S
I
(c d n t. )
S
S
I
C
- 4 9-
T a b le 4 - 2 .
V
R e la tiv e r e s is ta n c e o f b a rle y l in e s to v a rio u s i s o l a t e s o f
( r e s i s t a n t and i n t e r m e d i a t e r e a c t i o n s com b in ed ) .
PySiznopkom
R e s i s t a n t o r i n t e r m e d i a t e t o n i n e v i r u l e n c e ty p e s
C . I . 1615 (C)
C . I . 4207 (M)
C . I . 5298 (M)
C . I . 9768 (C)
C . I . 13262 (M)
U n ita n (M t. )
C . I . 5401 (C)
C . I . 5845 (C)
C . I . 7208 (C)
R e s i s t a n t o r i n t e r m e d i a t e t o e i g h t v i r u l e n c e ty p e s
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
1064
2235
5404.
5791
5822
6388
6475
6496
(M)
(C)
(C)
(C)
(C)
(C)
(C)
(M)
.
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
7272
7296
7297
7504
9440
9698
9699
9819
(C)
(M)
(C)
(C)
(C)
(M)
(M)
(C)
'
C . I . 9825 (C)
C . I . . 9831 (C)
C .I . 12821 (M)
C .I . 12860 (M)
C .I . 14023 (C)
S te p to e (M t.)
R e s i s t a n t o r i n t e r m e d i a t e to s e v e n v i r u l e n c e ty p e s
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
1197
5276
7447
7744
8332
9505
(M)
(M)
(M)
(C)
(C)
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
9647
9648
9702
9751
9758
9776
(C)
(C)
(M)
(M)
(M)
(C)
C .I . 9827
'C . I . 1 0 3 7 9
C . I . 11631
C . I . 13727
T ifa n g
(M)
(M)
(M)
(M)
R e s i s t a n t o r i n t e r m e d i a t e to s i x v i r u l e n c e t y p e s
C .I .
C .I .
C .I .
C .I ;
C .I .
C .I .
3430
4373
4638
5809
5810
7584
(C)
(M)
(C)
(C)
(C)
(C)
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
8333 (C)
9215 (M)
9263 (C)
9408 (M)
9881 (M)
10075 (M)
C .I .
C .I .
C .I .
C .I .
••
10781.
10903
13244
14265
(M)
(M)
(M)
(M)
R e s i s t a n t o r i n t e r m e d i a t e t o f i v e v i r u l e n c e ty p e s
C . I . 1261 (M)
C . I . 4428 (C)
C . I . 5172 (M)
C . I . 8952 (M)
C . I . 9567 (M)
C . I . 9584 (C)
C . I . 11978 (M)
C . I . 12875 (M)
C . I . 14033 .(M)
-50-
T a b le 4 - 2
(c o n t.)
R e s is ta n t o r in te r m e d ia te to f iv e v ir u le n c e ty p e s
C .I .
C .I .
C .I .
C .I .
5196
5199
6868
7339
(M)
(M)
(M)
(M)
C .I .
C .I .
C .I .
C .I .
9741
10070
11546
11578
(M)
(M)
(M)
(M)
( c o n t.)
C .I . 14127 (M)
. C . I . 14295 (M)
R e s is ta n t o r in te r m e d ia te to fo u r v ir u le n c e ty p e s
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
5108
7324
8270
8868
9214
9592
9669
(C)
(C)
(M)
(C)
(C)
(C)
C . I . 9693 (C)
C . I . 10778 (M)
C . I . 11977 (M)
C . I . 12674 (M)
C . I . 13749 (M)
C . I . 14103 (M)
F r e j a (M t. )
R e s i s t a n t o r i n t e r m e d i a t e t o t h r e e v i r u l e n c e : ty p e s
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
2216
4544
5057
5187
5376
9345
9350
(M)
(C)
(M)
(M)
(M)
(M)
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
C .I .
9569 (M)
10367 (M)
10624 (M)
10786 (M)
10905 (M)
11121 (M)
12034 (M)
Hypana (M t.)
K la g e s (M t.)
Lud (M t. ) .
M anker (M t. )
. P i r o l i n e ( M t.)
.. !
C . I . 12949 (M)
C . I . 13797 (M)
C . I . 14273 (M)
E r b e t (M t. )
G e o rg ie (M t.)
I n g r i d (M t.)
V anguard (M t. )
R e s i s t a n t o r i n t e r m e d i a t e t o two v i r u l e n c e t y p e s
C .I .
C .I .
C .I .
C .I .
C .I .
2330
9327 (M)
10364f (M)
10615 (M)
11056 (M)
C . I . 12894 (M)
C . I . 14093 (M)
C . I . 14218 (M)
H e c to r (M t.)
H o r s f o r d (M t.)
R e s i s t a n t o r i n t e r m e d i a t e t o o n e v i r u l e n c e ty p e
C . I . 4179 (M)
C . I . 7725 (M)
C . I . 10132 (M)
C . I . 14354 (M)
B e tz e s (M t.)
K a r l (M t.)
b a r k e r (M t.)
P a l l i s e r (M t. )
S h a b e t (M t. )
-51-
T a b le 4 - 2 ( c o n t . )
S u s c e p tib le to a l l n in e v ir u le n c e ty p e s
A rim o n t (M t.)
Compana (M t. )
E r b e t (M t. )
F irlb e c k s I I I
M o n a -A riv a t
(M t.)
-5 2 -
T a b le 4 - 3 .
R e la tiv e r e s i s t a n c e o f b a r le y l i n e s to n e t b lo tc h , in r e l a ­
t i o n t o p r e v i o u s s c r e e n i n g 't e s t s .
R e s is ta n t
to
L in e s
P re v io u s ly
T e s te d t o
M oroccan^
I s o la te s
L in e s
P re v io u s ly
T e s te d t o
N. A m erican
Is o la te s
M ontana
Grown
V a rie tie s
O th e r s
T o ta l
N in e t y p e s
O
3 (7.5% )
0
0
3 (2.0% )
E ig h t ty p e s
I (1.3% )
3 (7.5% )
0
0
4 (2.7% )
S even t y p e s
4 (5.1% )
4 (10.0% )
0
0
8 (5.4% )
S ix t y p e s
5 (6.4% )
7 (17.5% )
2 (8.7% )
I
15 (10.2% )
F iv e t y p e s
3 (3.8% )
5 (12.5% )
0
0
8 (5.4% )
Four ty p e s
12 (15.4% )
3 (7.5% )
I (4.3% )
0
16 (10.9% )
T h re e t y p e s
19 (24.4% )
5 (12.5% )
4 (17.4% )
2
30 (20.4% )
Two ty p e s
10 (12.8% )
7 (17.5% )
3 (13.0% )
0
20 (13.6% )
One ty p e
14 (17.9% )
3 (7.5% )
6 (26.1% )
2
25 (17.0% )
None
10 (12.8% )
0
7 (30.4% )
I
18 (12.2% )
78 (100%)
40 (100%)
23 (100%)
6
147 (100%),
g C ad d el a n d W ilc o x s o n , 1 9 7 5 .
B uchannon a n d M cD onald, 1 9 6 5 .
.
-5 3 -
T a b le 4 - 4 . R e l a t i v e r e s i s t a n c e o f b a r l e y l i n e s t o n e t b l o t c h , i n r e l a ­
t i o n t o p r e v i o u s s c r e e n i n g t e s t s ( r e s i s t a n t an d i n t e r m e d i a t e r e a c t i o n s
c o m b in e d ) .
R e s is ta n t
or In te rm e d ia te
to
P re v io u s ly
T e s te d t o
M oroccan
I s o la te s
P re v io u s ly
T e s te d t o
N. A m erican
Is o la te s
M ontana
Grown
V a rie tie s
O th e r s
T o ta l
N in e t y p e s
3 (3.8% )
5 (12.5% )
I
(4.3% )
0
9 (6.1% )
E ig h t ty p e s
,7 (9.0% )
14 (35.0% )
I (4.3% )
0
22 (15.0% )
Seven ty p e s
10 (12.8% )
5 (12.5% )
0
2
17 (11.6% )
S ix t y p e s
9 (11.5% )
7 (17.5% )
0
0
16 (10.9% )
F iv e t y p e s
17 (21.8% )
2 (5.0% )
0
0
19 (12.9% )
Four ty p e s
6 (7.7% )
6 (15.0% )
6 (26.1% )
I
.19 (12.9% )
T h re e t y p e s
15 (19.2% )
I (2.5% )
4 (17.4% )
i
21 (14.3% )
Two t y p e s
7 (9.0% )
0
6 (26.1% )
I
14 (9.5% )
One ty p e
4 (5.1% )
0
I (4.3% )
0
5 (3.4% )
None
0
0
4 (17.4% )
I
5 (3.4% )
78 (100%)
40 (100%)
23 (100%)
.
6
147 (100%)
C h a p te r 5
TESTING OF F^ POPULATION FOR RESISTANCE TO DIFFERENT ISOLATES
OF Vyn.iLyiopkofia. tzK-Lt,
Once s o u r c e s o f r e s i s t a n c e a r e i d e n t i f i e d , i t i s u s e f u l t o o b t a i n
i n f o r m a t i o n on t h e g e n e t i c s o f r e s i s t a n c e in v o lv e d i n t h e s e s o u r c e s
of re s is ta n c e .
I n f o r m a t io n c o n c e r n in g t h e num ber o f r e s i s t a n c e g e n e s
a v a i l a b l e , l i n e s w i t h common g e n e s f o r r e s i s t a n c e an d t h e mode o f
a c tio n o f th e s e genes i s n e c e s s a ry to e f f i c i e n t l y e x p lo it th e s e
p o t e n t ia l so u rc e s o f r e s i s ta n c e .
C r o s s e s w e re made b e tw e e n r e s i s t a n t l i n e s , b e tw e e n r e s i s t a n t
an d s u s c e p t i b l e l i n e s a n d b e tw e e n s u s c e p t i b l e l i n e s .
F^ p o p u la ­
t i o n s o f t h e s e c r o s s e s w e re t e s t e d t o d i f f e r e n t i s o l a t e s o f
Pyfl&no-
phofia teALA i n a n e f f o r t t o o b t a i n i n f o r m a t i o n r e g a r d i n g t h e g e n e t i c s
o f r e s i s t a n c e i n v o lv e d i n t h e s e c r o s s e s .
M a t e r i a l s and M ethods
I n t h e summer o f 1 9 7 7 , t h e c o m m e rc ia l v a r i e t i e s , U n i t a n , S t d p t o e ,
F i r l b e c k s I I I , H ypana an d G e o rg ia w e re c r o s s e d i n a l l p o s s i b l e com­
b in a tio n s w ith each o th e r .
E ach o f t h e s e v a r i e t i e s w as a l s o c r o s s e d
w i t h t h e v a r i e t i e s B e tz e s a n d T if a n g and t h e l i n e s , C .I* 9 8 19,
C . 1 . 9 7 7 6 , C . I . 7584. a n d C . I . 5 7 9 1 .
The c o m m e rc ia l v a r i e t i e s w ere
c h o s e n on t h e b a s i s o f e a r l i e r t e s t s w h ic h i n d i c a t e d t h e s e v a r i e t i e s
c o n ta i n e d r e s i s t a n c e t o P.
teAeA .
T en F^ s e e d s o f e a c h o f t h e s e
c r o s s e s w e re t h e n s e n t t o A riz o n a an d grow n d u r in g t h e w i n t e r o f ■
-55-
1 9 7 7 -7 8 .
The f o u r m o st v ig o r o u s
p l a n t s w e re c h o s e n , w h e re p o s s i b l e ,
f o r h a r v e s t i n g F^ s e e d .
F^ s e e d o f c r o s s e s made by D r. H a ro ld B ockelm an d u r in g the. summer
o f 1976. w e re a l s o t e s t e d
T h e se c r o s s e s w e re :
T if a n g X C . I . 4544
C . I . 5791 X T if a n g
C . I . 9819 X C . I . 1197
T if a n g X C . I . 2330
C . I . 7584 X T if a n g
C . I . 9819 X C . I . 5791
T if a n g X C . I . 5791
C . I . 9819 X T if a n g
C . I . 7584 X C . I . 9819
T if a n g X C . I . 7584
C .I .
7584 X C . I .
5791
C . I . 7584 X 'C . I . 1197
T if a n g X C . I . 9819
C .I .
9819 X C . I .
2235
C . I . 7584 X C . I . 9776
T if a n g X C . I . 9776
C .I .
2235 X C . I .
9819
C . I . 2235 X T if a n g
C .I .
9819 X C . I .
9776
T e s t i n g o f t h e Fg s e e d was p e rf o r m e d i n t h e g r e e n h o u s e .
T w en ty -
f i v e Fg s e e d s w e re p l a n t e d i n e a c h o f s i x row s a c r o s s t h e w id th o f
m e t a l f l a t s 1 4 " x 1 0 " x 3 " , w i t h h a l f row s p l a n t e d w i t h t e n s e e d s o f
e a c h p a r e n t , a s u s c e p t i b l e c h e c k (D e k a p ), a n d , when a v a i l a b l e , F^
seed.
F o u r f l a t s o f e a c h c r o s s W ere p l a n t e d f o r e a c h i s o l a t e to
w h ic h t h e c r o s s was t e s t e d , w i t h e a c h f l a t c o n t a i n i n g Fg s e e d fro m o n e
o f t h e f o u r F^ p l a n t s h a r v e s t e d i n A r iz o n a .
The i s o l a t e s o f P.
teAU
u s e d i n t h e t e s t s w e re grow n on V8 j u i c e a g a r i n a n i n c u b a t i o n cham ber
a t 1 7 - 1 8 ° C, w i t h a n e i g h t h o u r p h o t o p e r i o d .
C u l t u r e s w e re t r a n s ­
f e r r e d on t h e same d ay t h e s e e d w as p l a n t e d .
I n o c u l a t i o n to o k p l a c e
when t h e p l a n t s w e re 7 -8 d a y s o l d .
C o n i d i a l s u s p e n s i o n s w e re u s e d
-5 6 -
a s in o c u lu m w i t h 0 .1 ml o f 1% Tween 20 ad d ed p e r 100 m l o f in o c u lu m .
The in o c u lu m was s p r a y e d on t h e p l a n t s u s in g an a t o m iz e r d r i v e n by
c o m p re s se d a i r .
fla t.
F i f t e e n t o e i g h t e e n ml o f in o c u lu m w e re u s e d p e r
The s p o r e c o n c e n t r a t i o n was n o t s t a n d a r d i z e d , w i t h c o n c e n t r a ­
t i o n s r a n g i n g fro m 1 0 ,0 0 0 r- 9 0 ,0 0 0 s p o r e s p e r m l.
In o c u la te d p la n ts
w e re p l a c e d i n a dew cham ber a t 100% r e l a t i v e h u m id ity an d no l i g h t .
The w a l l t e m p e r a t u r e was k e p t a t 7° C, and t h e w a te r b a t h a t 35. C,
w i t h a. r e s u l t i n g a i r te m p e r a t u r e o f 24 - 2 7 ° C.
A f t e r 2 0 -2 4 h o u r s ,
t h e p l a n t s w e re rem oved fro m t h e dew cham ber and p l a c e d on b e n c h e s .
in an is o l a ti o n g ree n h o u se .
D is e a s e symptom s w e re r e a d 7 -8 d a y s a f t e r
in o c u la tio n .
R e s u l t s an d D i s c u s s i o n
T a b le 5 - 1 l i s t s
fe re n t is o la te s .
used.
th e r e s u l t s o f th e t e s t s o f th e c r o s s e s to d i f ­
The t e s t s a r e g ro u p e d on t h e b a s i s o f th e i s o l a t e
T h e r e f o r e , c r o s s e s a r e l i s t e d m ore t h a n o n c e , w ith th e r e a c t i o n s
o f th e p a re n ts ,
g e n e r a t i o n (w h e n e v er a v a i l a b l e ) an d F^ g e n e r a t i o n
to th e d i f f e r e n t i s o l a t e s l i s t e d a c c o rd in g ly .
The d i f f e r e n t r e a c t i o n
t y p e s o f t h e p a r e n t s a n d F^ g e n e r a t i o n s a r e l i s t e d .
The r e a c t i o n
t y p e s o f t h e F^ g e n e r a t i o n s a r e s e p a r a t e d i n t o r e s i s t a n t and s u s c e p ­
t i b l e t y p e s , w i t h t h e r e a c t i o n t y p e s I , 2 and 3 c o n s i d e r e d r e s i s t a n t
and r e a c t i o n ty p e 4 c o n s id e r e d s u s c e p t i b l e .
‘
-5 7 -
B a r le y l i n e s w i t h g e n e s i n common.
The d e t e r m i n a t i o n o f common
genes fo r r e s is ta n c e in d i f f e r e n t b a rle y lin e s i s r e l a ti v e ly s tr a ig h t ­
fo rw a rd .
The
g e n e r a t i o n o f a c r o s s b e tw e e n two r e s i s t a n t b a r l e y
l i n e s s h o u ld c o n t a i n no s u s c e p t i b l e p l a n t s i f
common g e n e f o r r e s i s t a n c e .
■
t h e two p a r e n t s s h a r e a
B e c a u se o f t h e p o s s i b i l i t y o f m ixed s e e d ,
t h e o c c u r r e n c e o f a s m a ll am ount o f o u t c r o s s i n g , and t h e a p p e a r a n c e
o f o f f t y p e s ,' s u s c e p t i b l e p l a n t s c a n o c c u r i n c r o s s e s b e tw e e n l i n e s
s h a r i n g a common g e n e f o r r e s i s t a n c e .
H ow ever, t h e p e r c e n t a g e o f s u s ­
c e p t i b l e p l a n t s i n t h e F^ g e n e r a t i o n s h o u ld b e low e n o u g h t h a t t h e
r a t i o o f r e s i s t a n t to s u s c e p tib le p la n ts w i l l n o t e a s i l y f i t th e ex­
p e c te d r a t i o o f a n y p r o b a b l e gene m o d e ls .
Of t h e c r o s s e s t e s t e d i n t h i s s t u d y , f o u r a p p e a r e d t o s h a r e a
common g e n e f o r r e s i s t a n c e a g a i n s t e v e r y i s o l a t e o f
t h e y w e re t e s t e d .
T h e se c r o s s e s w e r e :
P. it2A2A t o w h ic h
U n ita n x S t e p t o e , Q .1 . 5791
x U n i t a n , C . I . 5791 x S t e p to e a n d T if a n g x C . I . 9819 ( T a b le 5 - 2 ) .
The r e s u l t s o f t h e s e t e s t s i n d i c a t e t h a t U n i t a n , S t e p to e and
C . I . 5791 c o n t a i n much t h e same g e n e t i c i n f o r m a t i o n f o r r e s i s t a n c e
t o P.
t.eAQJ).
T h e re i s e v id e n c e t h a t S t e p to e and C . I . 5791 do n o t
c o n t a i n i d e n t i c a l g e n e s f o r r e s i s t a n c e , th o u g h .
When t h e c r o s s e s
C . I . 9819 x C . I . 5791 an d C . I . 9819 x S t e p to e w e re t e s t e d t o Mor 1 5 ,
C . I . 9819 and C . I . 5791 a p p e a r e d t o s h a r e a common g e n e f o r r e s i s ­
t a n c e , w h i l e t h e F^ g e n e r a t i o n o f t h e c r o s s C . I . 9819 x S t e p to e s e g ­
r e g a t e d i n a 1 5 :1 r a t i o
of
r e s i s t a n t to s u s c e p tib le p l a n t s
(T a b le 5 - 1 ) .
—5 8 -
T h is i n d i c a t e d t h a t C. I . 9819 a n d S t e p t o e e a c h c o n t a i n a s i n g l e d i f ­
f e r e n t d o m in a n t g e n e f o r r e s i s t a n c e .
T h is i s a l s o e v id e n c e t h a t C . I .
5791 a n d S t e p to e do n o t c o n t a i n t h e sam e g e n e s f o r r e s i s t a n c e .
The
c r o s s U n ita n x S t e p to e was t e s t e d t o Mor 15 and t h e r e i s e v id e n c e
t h a t t h e s e two v a r i e t i e s s h a r e a common g en e e f f e c t i v e a g a i n s t t h i s
is o la te
( T a b le 5 - 1 ) .
S in c e b o t h U n ita n an d S t e p to e a p p e a r t o c o n t a i n
o n ly o n e d o m in a n t g en e f o r r e s i s t a n c e t o Mor 1 5 , t h i s s u g g e s t s t h a t
U n ita n a n d C . I . 5791 a l s o do n o t c o n t a i n i d e n t i c a l g e n e s f o r r e s i s ­
ta n c e .
The c r o s s T if a n g x C . I , 9819 a n d i t s r e c i p r o c a l , C . I . 9819 x
T i f a n g , a l s o a p p e a r e d t o h a v e common g e n e s f o r r e s i s t a n c e t o t h r e e
i s o l a t e s o f P.
X.2AU.
T if a n g i s s u s c e p t i b l e t o s e v e r a l i s o l a t e s ,
f o r e x a m p le Mt 7 7 -1 an d Mt 7 7 -5 1 , w h ile C . I . 9819 i s r e s i s t a n t , i n ­
d i c a t i n g t h a t C . I . 9819 c o n t a i n s a d d i t i o n a l g e n e s f o r r e s i s t a n c e o t h e r
th a n th o s e i t s h a re s w ith T ifa n g .
O th e r c r o s s e s show ed e v id e n c e f o r
s h a r i n g g e n e s f o r r e s i s t a n c e to som e, b u t n o t a l l , o f t h e i s o l a t e s
t o w h ic h th e y w e re t e s t e d , i n d i c a t i n g t h e l i n e s i n v o lv e d i n t h e s e
c r o s s e s d id n o t c o n t a i n i d e n t i c a l g e n e s f o r r e s i s t a n c e .
I n s e v e r a l c r o s s e s , su c h a s S t e p to e x C . I . 9776 a n d U n ita n x
C . I . 9 7 7 6 , t h e num ber o f s u s c e p t i b l e p l a n t s t h a t a p p e a r e d i n t h e F 2
g e n e r a t i o n p ro d u c e d a r a t i o w h ic h f i t a g en e m odel c o n s i s t i n g o f t h r e e
d o m in a n t g e n e s .
B e c a u se t h e p a r e n t s do c o n t a i n m ore t h a n one. gene
f o r r e s i s t a n c e , t h i s ty p e o f g e n e m o d el i s v e r y p o s s i b l e .
The g en e
-59-
ra tio
f o r t h r e e d o m in a n t g e n e s an d a s i t u a t i o n i n w h ic h a few s u s ­
c e p tib le p la n ts a p p e a r in th e
g e n e r a t i o n o f a c r o s s i n w h ich th e
p a r e n t s s h a r e a common g en e f o r r e s i s t a n c e c a n n o t r e a d i l y be d i s t i n ­
g u is h e d w i t h o u t t e s t i n g
lin e s .
T h e r e f o r e , c r o s s e s o f t h i s 't y p e
a r e l i s t e d a s h a v in g p o s s i b l e g e n e s i n common (T a b le 5 - 2 ) .
Number o f g e n e s f o r , r e s i s t a n c e t o P.
teA n i.
I t . was p o s s i b l e , from
t h e d a t a , t o d e te r m in e a minimum num ber o f g e n e s f o r r e s i s t a n c e i n e a c h
l i n e , b u t due to t h e p o s s i b i l i t y , a n d p r o b a b le o c c u r r e n c e , o f g e n e s f o r
r e s i s t a n c e b e in g e f f e c t i v e a g a i n s t m ore t h a n one i s o l a t e o f P.
a d e f i n i t e num ber o f g e n e s c o u ld n o t be d e te r m in e d
S te p to e .
tetiQA,
(T a b le 5 - 3 ) .
C r o s s e s w i t h s u s c e p t i b l e v a r i e t i e s i n d i c a t e d t h a t S t e n to e
c o n t a i n s tw o .d o m in a n t g e n e s f o r r e s i s t a n c e t o s e v e r a l i s o l a t e s , i n c l u d ­
in g Mt 7 7 -3 and Mt 7 7 - 6 .
T h e re i s a l s o e v id e n c e t h a t S t e o to e s h a r e s
a common g e n e f o r r e s i s t a n c e w i t h B e tz e s e f f e c t i v e a g a i n s t Mor 1 8 .
S in c e B e tz e s i s s u s c e p t i b l e t o Mt 7 7 -6 and Mt 7 7 - 3 , t h i s common g en e
m u st b e d i f f e r e n t t h a n t h e two g e n e s e f f e c t i v e a g a i n s t t h e s e i s o l a t e s .
T h e r e f o r e , S t e p to e p r o b a b ly c o n t a i n s a t l e a s t t h r e e d o m in a n t g e n e s
f o r r e s i s t a n c e t o P.
U n ita n .
te A U .
U n ita n a l s o c o n t a i n s two dom inant, g e n e s f o r r e s i s t a n c e
e f f e c tiv e a g a in s t s e v e ra l i s o l a te s ,
i n c l u d i n g P t S - 2 and Mt 7 7 - 3 ,
b a s e d on c r o s s e s w i t h s u s c e p t i b l e v a r i e t i e s .
U n ita n a l s o p r o b a b ly
s h a r e s w i t h B e tz e s a common g e n e f o r r e s i s t a n c e e f f e c t i v e a g a i n s t Mor 18
S in c e B e tz e s i s
s u s c e p t i b l e t o P t S -2 a n d Mt 7 7 - 3 , U n i t a n , l i k e S t e p t o e ,
—6 0 —
p r o b a b l y c o n t a i n s a t l e a s t t h r e e d o m in a n t g e n e s f o r r e s i s t a n c e .
C .I . 9 8 1 9 .
C .I . 9819 s h a r e s common g e n e s f o r r e s i s t a n c e t o P t S-2
w i t h T if a n g and U n ita n .
I t a l s o s h a r e s a g en e f o r r e s i s t a n c e e f f e c t i v e
a g a i n s t Mor I w i t h T i f a n g , b u t n o t U n ita n .
T h is g e n e e f f e c t i v e a g a i n s t
Mor I i s t h e r e f o r e d i f f e r e n t t h a n t h e o n e e f f e c t i v e a g a i n s t P t S -2 .
C .I .
9819 i s r e s i s t a n t t o Mt 7 7 - 1 , an i s o l a t e t o w h ic h T if a n g i s s u s ­
c e p tib le .
The g e n e i n C . I .
9819 e f f e c t i v e a g a i n s t Mt 7 7 -1 i s t h e r e ­
f o r e d i f f e r e n t t h a n e i t h e r t h e g e n e f o r r e s i s t a n c e t o Mor I o r t h e
g e n e e f f e c t i v e a g a i n s t P t S -2 .
C . I . 9819 t h e r e f o r e c o n t a i n s a t l e a s t
t h r e e d o m in a n t g e n e s f o r r e s i s t a n c e .
C .I . 5 7 9 1 .
C .I .
C . I . 5791 s h a r e s a common g en e f o r r e s i s t a n c e w ith
7584 e f f e c t i v e a g a i n s t Mor 1 8 .
n a n t g e n e s f o r r e s i s t a n c e t o Mor I .
C . I . 5791 a l s o c o n t a i n s two domi-r
C . I . 7584 i s s u s c e p t i b l e t o Mor I .
T h e r e f o r e , t h e g e n e f o r r e s i s t a n c e s h a r e d by C .I . 5791 and C .I . 7584 i s
d i f f e r e n t from t h e two g e n e s l o c a t e d i n C . I . 5791 w h ic h a r e e f f e c t i v e
a g a i n s t Mor I .
C .I . 5791, th e n , c o n ta in s a t l e a s t th r e e genes f o r r e ­
s i s t a n c e t o P.
T ifa n g .
.
T if a n g a n d C .I . 7584 h a v e a g en e i n common e f f e c t i v e
a g a i n s t P t S -2 .
to P t 8.
gen es.
They e a c h c a r r y s i n g l e d i f f e r e n t g e n e s f o r r e s i s t a n c e
A t h i r d g e n e c a n n o t b e p o s i t i v e l y s e p a r a t e d from t h e s e two
T if a n g c o n t a i n s a t l e a s t two g e n e s f o r r e s i s t a n c e .
C .I . 7 5 8 4 .
C . I . 7584 c o n t a i n s a g e n e i n common w i t h T if a n g f o r
r e s i s t a n c e t o P t S - 2 , p l u s a s i n g l e d o m in a n t g en e e f f e c t i v e a g a i n s t P t 8
—6 1 —
d i f f e r e n t th a n t h a t i n T i f a n g .
C .I .
7584 c o n t a i n s a t l e a s t two g e n e s
fo r re s is ta n c e .
C .I . 1 197.
C . I . 1197 and C . I . 9819 s h a r e a common g e n e f o r r e ­
s i s t a n c e t o Mor 1 5 , y e t h av e d i f f e r e n t g e n e s f o r r e s i s t a n c e to
7 7 -1 .
C . I . 1197 and C . I . 7584 h a v e a g e n e i n common f o r r e s i s t a n c e to A ust I ,
b u t a r e d i s s i m i l a r i n r e s i s t a n c e t o Mor 1 5 .
From t h i s
i t c a n be c o n ­
c lu d e d t h a t C .I . 1197 h a s a t l e a s t two g e n e s f o r r e s i s t a n c e .
C .I . 9776.
C . I . 9776 and C . I . 7584 s h a r e a common g e n e f o r r e ­
s i s t a n c e t o P t S -2 .
s u s c e p tib le .
C .I .
9776 i s r e s i s t a n t t o Mor I and C .I . 7584 i s
C . I . 9776 m u st t h e r e f o r e c o n t a i n a n o t h e r g e n e f o r r e ­
s i s t a n c e o t h e r t h a n t h e o n e i t s h a r e s w i t h C . I . 75 8 4 .
h a s a t l e a s t two g e n e s f o r r e s i s t a n c e t o P.
C .I . 2235.
H en ce, C .I . 9776
t&i&A.
C r o s s e s w i t h C . I . 9819 t e s t e d t o P t T - I and Mt 7 7 -1
i n d i c a t e t h a t C . I . 2235 h a s a t l e a s t one d o m in a n t g en e f o r r e s i s t a n c e to
P. to f ld t,.
B e tz e s .
B e tz e s s h a r e s a common g e n e f o r r e s i s t a n c e to Mor 18
w i t h S t e p to e a n d U n ita n .
B e tz e s a l s o h a s a g en e i n common w ith
G e o r g ie e f f e c t i v e a g a i n s t ELS 7 7 - 6 .
I t c a n n o t b e d e te r m in e d w h e th e r
o r n o t t h i s i s t h e same g e n e o r d i f f e r e n t g e n e s .
l e a s t one gene f o r r e s i s t a n c e to
G e o r g ie .
B e tz e s c o n t a i n s a t
P. :t2A eJ> ,
G e o rg ie h a s a t l e a s t o n e g en e f o r r e s i s t a n c e i n common
w i t h B e t z e s , e f f e c t i v e a g a i n s t ELS 7 7 - 6 .
F irlb e c k s I I I .
F i r l b e c k s I I I c o n t a i n s a t l e a s t one d o m in a n t gene
-6 2 -
e f f e c t i v e a g a i n s t Mor 1 8 , d i f f e r e n t t h a n t h a t fo u n d i n B e t z e s . '
C . I . 2330 a n d C . I . 4 5 4 4 .
C . I . 2330 and C .I . 4544 e a c h s h a r e a
common g e n e f o r r e s i s t a n c e w i t h T if a n g e f f e c t i v e a g a i n s t P t S -2 .
T h is
i s t h e o n ly i s o l a t e t o w h ic h t h e s e l i n e s w ere t e s t e d .
T o t a l num ber o f r e s i s t a n c e g e n e s .
The t o t a l num ber o f d i f f e r e n t
r e s i s ta n c e genes a v a ila b le in th e s e b a rle y l in e s c a n n o t be d e te rm in e d .
fro m t h e s e d a t a .
A minimum num ber o f r e s i s t a n c e g e n e s c a n be d i s ­
t i n g u i s h e d , h o w e v e r.
U n i t a n , C .I . 9819 a n d C . I . 5791 a l l h a v e a t
l e a s t th re e genes fo r r e s is ta n c e .
I n d i r e c t e v id e n c e s u g g e s t s t h a t w h i l e
C .I . 9819 and C . I . 5791 s h a r e a common g e n e f o r r e s i s t a n c e t o Mor 1 5 , .
C .I . 5791 an d U n ita n do n o t .
C . I . 5791 and U n ita n p r o b a b ly do s h a r e a
common g e n e f o r r e s i s t a n c e t o M o r. I , w h ile C .I . 9819 a n d U n ita n do
not
(T a b le 5 - 1 ) .
T h is s u g g e s t s t h a t t h e r e s i s t a n c e
in
C . I . 9819
e f f e c t i v e a g a i n s t Mor I i s d i f f e r e n t t h a n t h e r e s i s t a n c e i n C . I . 5791
e f f e c tiv e a g a in s t t h i s i s o la te .
T h e re e x i s t s , t h e n , t h r e e b a r l e y l i n e s , e a c h w i t h a t l e a s t t h r e e
d i f f e r e n t g enes f o r r e s i s t a n c e , y e t none o f th e th r e e a r e i d e n t i c a l
in r e s is ta n c e .
F o r e x a m p le , U n ita n may c o n t a i n t h r e e g e n e s , P t a ,
P t b a n d P t c , w i t h g e n e P t a. e f f e c t i v e a g a i n s t . P t S - 2 , gene P t b
e f f e c t i v e a g a i n s t Mor I an d gene P t c e f f e c t i v e a g a i n s t Mor 15.
C .I . 5791 c o u ld t h e n c o n t a i n P t a an d P t b s i n c e i t h a s g e n e s i n common
w ith U n ita n f o r r e s i s t a n c e t o P t S -2 a n d Mor I , b u t i t m u st h a v e a
d i f f e r e n t g e n e , g en e P t d , e f f e c t i v e a g a i n s t Mor 1 5 .
C . I . 9319 c o n t a i n s
-63-
g e n e s P t a an d P t d , s i n c e i t s h a r e s a common g en e f o r r e s i s t a n c e , t o
P t S - 2 w i t h U n ita n a n d t o Mor 15 w i t h C . I . 5 7 9 1 , b u t i t m ust h av e
a n o t h e r d i f f e r e n t g e n e e f f e c t i v e a g a i n s t Mor I , g e n e P t e .
One may t h e n c o n c lu d e t h a t a t l e a s t f i v e g e n e s f o r r e s i s t a n c e
e x i s t , w i t h U n ita n c o n t a i n i n g g e n e s P t a , P t b , an d P t c , C .T . 5791
c o n t a i n i n g g e n e s P t a , P t b , a n d P t d , and C . I . 9819 c o n t a i n i n g t h e
g e n e s P t a , P t d and P t e .
The d e s i g n a t i o n o f d i f f e r e n t l e t t e r s t o )
e a c h g e n e i s f o r t h e s a k e o f e x p l a n a t i o n o n ly .
The e v id e n c e f o r t h e o c c u r r e n c e o f f i v e g e n e s i s i n d i r e c t , y e t
t h i s e x p la n a tio n i s p la u s ib le .
F u rth e r t e s t s , e s p e c i a l l y t e s t s i n ­
v o l v in g F^ l i n e s from t h e s e c r o s s e s , m u st be p e rfo rm e d b e f o r e m ore
c o n c lu s iv e in fo rm a tio n i s o b ta in e d .
I t m u st be s t r e s s e d t h a t t h e s e
f i v e g e n e s a r e t h e minimum num ber t h a t c o u ld b e d i s t i n g u i s h e d and i t
i s p o s s i b l e t h a t w i t h f u r t h e r t e s t i n g m ore g e n e s w i l l b e d i f f e r e n ­
tia te d .
I t w as n o t p o s s i b l e t o c o n f i d e n t l y d i s t i n g u i s h b e tw e e n a s i t u a ­
t i o n i n v o l v i n g t h r e e d o m in a n t g e n e s a n d one i n v o l v i n g a common g e n e
f o r r e s i s t a n c e when low p e r c e n t a g e s o f s u s c e p t i b l e p l a n t s a p p e a r e d .
The p o s s i b i l i t y o f l i n k a g e a l s o e x i s t s .
F u r th e r s t u d i e s i n v o lv i n g F
f a m i l i e s a r e n e c e s s a r y i n o r d e r t o make a n y c o n c l u s i o n s in v o lv i n g
th e s e p o s s i b i l i t i e s .
T if a n g was fo u n d t o h a v e a s i n g l e , in c o m p le t e ly d o m in a n t .gene
f o r r e s i s t a n c e t o a C a l i f o r n i a i s o l a t e o f P.
( S c h a l l e r , 1 9 5 5 ).
” 64—
T h is g e n e w as fo u n d t o b e l i n k e d t o a r e s i s t a n c e g e n e i n C . I . 4797
a n d C . I . 2750 w i t h a r e c o m b in a tio n p e r c e n t a g e o f 2 .5 7
S c h a lle r , 1 9 5 8 ).
(Mode and
Khan and Boyd (1 9 6 9 b ) fo u n d T if a n g a n d C . I . 4797 t o
h a v e a common g e n e f o r r e s i s t a n c e t o a n A u s t r a l i a n i s o l a t e o f P.
From t h i s t h e i n f e r e n c e c a n be made t h a t T if a n g h a s two g e n e s
f o r r e s i s t a n c e t o P.
tQA&A.
Khan an d Boyd (1 9 6 9 b ) a l s o fo u n d t h a t
T i f a n g , C . I . 23 3 0 , C . I . 4 7 9 7 , C . I . 9819 and C . I . 5791 a l l s h a r e a
common g e n e f o r r e s i s t a n c e t o t h i s A u s t r a l i a n i s o l a t e .
The r e s u l t s
o f t h e p r e s e n t s tu d y i n d i c a t e two g e n e s f o r r e s i s t a n c e i n T ifa n g
w i t h T if a n g h a v in g g e n e s i n common w i t h C . I . 23 3 0 , C . I . 9819 and n o s s i b l y C . I . 5 7 91.
B o c k e lm a n , e t a l .
( 1 9 7 7 ) , fo u n d T if a n g t o c o n t a i n a s i n g l e dom­
i n a n t g e n e f o r r e s i s t a n c e t o P t 8 , l o c a t e d on chrom osom e 3 , and C . I .
7584 t o c o n t a i n a s i n g l e g e n e f o r r e s i s t a n c e t o P t 8 l o c a t e d on chom o some 2 .
The d a t a from , t h e p r e s e n t s tu d y i n d i c a t e t h a t T if a n g and
C .I . 7584 c o n t a i n s i n g l e , d i f f e r e n t d o m in a n t g e n e s f o r r e s i s t a n c e
to P t 8.
E x p r e s s io n o f g e n e t i c r e s i s t a n c e .
In s e v e r a l in s ta n c e s , th e
r e a c tio n o f a b a rle y l in e to a p a r t i c u l a r
te s t.
i s o l a t e v a r i e d from t e s t t o
T h is was e s p e c i a l l y e v id e n t w i t h T i f a n g , b u t a l s o o c c u r r e d w i t h
C .I . 7584.
c e p tib le
T if a n g v a r i e d from a n i n t e r m e d i a t e
( 2 ,3 ) t o a t o t a l l y s u s ­
(4 ) r e a c t i o n i n r e s p o n s e t o t h e i s o l a t e P t R .
fro m a n i n t e r m e d i a t e ( 2 ,3 ) t o a s u s c e p t i b l e
I t a ls o v a rie d
( 4 ,3 ) r e a c t i o n i n r e s p o n s e
—65 —
t o Mor I .
ta n t
(2 )
The r e a c t i o n o f C .I . 7584 v a r i e d from a m o d e r a te ly r e s i s ­
r e a c tio n to a s u s c e p tib le
Mor 15 a n d fro m a r e s i s t a n t
( 4 ,3 ) r e a c t i o n when t e s t e d w ith
( I ) to a v a r ia b le
( 2 , 4 , 3 ) ty p e o f r e a c t i o n
i n r e s p o n s e t o P t R.
The c a u s e o f t h i s v a r i a t i o n c o u ld n o t b e d e te r m i n e d .
Khan and
Boyd ( 1 9 6 9 c ) .o b s e r v e d a b reak d o w n i n r e s i s t a n c e o f C . I . 2330 w ith
in c r e a s in g sp o re c o n c e n tr a tio n , b u t n o t w ith T ifa n g .
T h e re was no
c o r r e l a t i o n b e tw e e n s p o re , c o n c e n t r a t i o n an d r e s i s t a n c e i n t h e t e s t s
p e rfo rm e d d u r in g t h e p r e s e n t s t u d y .
Khan ( 1 9 6 9 ), and Khan and Boyd
(1 9 6 9 c ) a l s o fo u n d t h e t e m p e r a t u r e d u r in g t h e o r e - i n o c u l a t i o n p e r i o d ,
th e . i n c u b a t i o n p e r i o d and t h e p o s t i n o c u l a t i o n p e r i o d t o h a v e a n e f ­
f e c t on t h e r e s i s t a n c e o f some v a r i e t i e s . , b u t n o t o t h e r s .
t e m p e r a t u r e s w e re n o t r e c o r d e d f o r e a c h t e s t ,
b e n e i t h e r d i s c o u n t e d n o r c o n f ir m e d .
T h ese
so t h e i r e f f e c t s c a n
The p o s s i b i l i t y o f c h a n g e s i n
t h e v i r u l e n c e o f t h e i s o l a t e s u s e d m u st a l s o b e c o n s i d e r e d .
The v a r i a b i l i t y o f t h e p a r e n t s e x te n d e d t o t h e
g e n e ra tio n .
F o r e x a m p le , t h e c r o s s C . I . 7584 x T if a n g was t e s t e d tw ic e to P t R.
I n o n e t e s t C . I . 7584 showed a r e s i s t a n t
in te rm e d ia te
( 2 ,3 ) a n d th e . F^ g e n e r a t i o n showed a t o t a l o f 346 r e s i s ­
t a n t a n d 58 s u s c e p t i b l e p l a n t s .
ia b le
( 1 ,2 ) r e a c t i o n , T ifa n g was
I n t h e o t h e r t e s t C . I . 7584 was v a r ­
( 2 , 4 , 3 ) i n r e a c t i o n , T if a n g w as s u s c e p t i b l e
(4 ) a n d t h e F?
g e n e r a t i o n h ad 72 r e s i s t a n t and 304 s u s c e p t i b l e p l a n t s .
T h a t t h e two. p a r e n t s r e a c t e d s i m i l a r l y i n b o th t e s t s i n d i c a t e s
-6 6 -
t h a t t h e f a c t o r s c a u s i n g a b reak d o w n i n r e s i s t a n c e a r e p r o b a b ly t h e
sam e f o r b o t h l i n e s .
is a p o s s ib ility
B e c a u se o f t h e c h a n g e o f t h e F2 r e a c t i o n , t h e r e
t h a t r a d i c a l l y d i f f e r e n t c o n c lu s i o n s c o n c e r n in g t h e
.
ty p e o f r e s i s t a n c e i n v o lv e d c o u ld b e drawn..
Khan (1 9 6 9 ) fo u n d t h a t v a r i a b i l i t y o f h o s t r e a c t i o n i n t h e p r o ­
geny o f r e s i s t a n t v a r i e t i e s was i n f l u e n c e d by t h e g e n e t i c b a c k g ro u n d
o f th e s u s c e p tib le p a re n t u se d .
By u s i n g t h e r e s i s t a n t l i n e C. I ..
5791 a n d t h e s u s c e p t i b l e l i n e s D am pier and A t l a s , he show ed t h a t t h e
F2 g e n e r a t i o n o f D am pier x C . I . 5791 e x p r e s s e d a h i g h e r d e g r e e o f
r e s i s t a n c e t h a n t h e F2 g e n e r a t i o n o f A t l a s x C . I . 5 7 9 1 .
The F^ g e n ­
e r a t i o n o f t h e c r o s s w i t h D am pier a l s o showed a h i g h e r d e g r e e o f r e ­
s i s t a n c e t h a n t h e F^ o f t h e c r o s s w i t h A t l a s .
I n t h e p r e s e n t s t u d y , e v id e n c e was fo u n d s u p p o r t i n g t h e d i f f e r ­
e n t i a l e f f e c t s o f s u s c e p t i b l e v a r i e t i e s on t h e e x p r e s s i o n o f r e s i s ­
ta n c e .
The s u s c e p t i b l e v a r i e t i e s H ypana and G e o rg ia w e re c r o s s e d
w i t h t h e r e s i s t a n t v a r i e t i e s S t e p to e and U n ita n and t h e r e s i s t a n t
l i n e C .I . 7584.
P t R.
The F^ and Fg g e n e r a t i o n s w e re t e s t e d t o t h e i s o l a t e
The c r o s s e s i n v o l v i n g H y p an a. show ed a h i g h e r d e g r e e o f r e s i s ­
t a n c e i n b o th t h e F^ a n d Fg g e n e r a t i o n s th a n t h e c r o s s e s in v o lv i n g
G e o rg ia (T a b le 5 - 4 ) .
T h e se r e s u l t s i n d i c a t e t h a t t h e g e n e t i c b a c k /
g ro u n d o f H ypana i s m ore c o n d u c iv e t o t h e e x p r e s s i o n o f r e s i s t a n c e
th a n t h e g e n e t i c b a c k g ro u n d o f G e o r g ia .
P o s s i b l e a d d i t i v e r e s i s t a n c e i n b a r l e y t o P.
toAlM .
F iv e c r o s s e s
—6 7 -
w e re t e s t e d , u s in g i s o l a t e s t o w h ic h b o th p a r e n t s i n e a c h c r o s s w e re
s u s c e p tib le .
I t w o u ld b e e x p e c te d t h a t a c r o s s i n v o l v i n g two s u s ­
c e p t i b l e p a r e n t s w o u ld r e s u l t i n a s u s c e p t i b l e F2 p o p u l a t i o n .
How­
e v e r , i n t h e F2 p o p u l a t i o n s o f t h e s e c r o s s e s t h e r e a p p e a r e d p l a n t s
sh o w in g a h i g h e r d e g r e e o f r e s i s t a n c e t h a n e i t h e r p a r e n t (T a b le 5 - 5 ) .
T h is o b s e r v e d t r a n s g r e s s i v e s e g r e g a t i o n s u g g e s t s t h e p o s s i b i l i t y
o f a d d itiv e r e s i s ta n c e to
P. to A U .
I t i s p o s s ib le th a t th e su scep ­
t i b l e l i n e s c o n t a i n g e n e s w h ich a r e n o t e f f e c t i v e by t h e m s e lv e s , b u t
when com bined p ro d u c e a n o b s e r v a b l e r e s i s t a n t r e a c t i o n .
I t must, be
p o in te d o u t t h a t e a ch o f th e l i n e s u sed a s p a re n ts i n th e s e c ro s s e s
c o n ta in s a t l e a s t one gene f o r r e s i s ta n c e e f f e c tiv e a g a in s t o th e r
is o la te s of
P. tVlQA.
T h e se g e n e s a p p e a r to h a v e a m a jo r e f f e c t
a g a i n s t t h e i s o l a t e s t o w h ic h th e y a r e e f f e c t i v e .
I f t h e s e m a jo r
e f f e c t g e n e s a r e d i f f e r e n t , th e n i t i s p o s s i b l e t h a t when th e y a r e
com bined th e y w i l l h a v e a n a d d i t i v e e f f e c t a g a i n s t i s o l a t e s to w h ic h
each a lo n e i s i n e f f e c t i v e .
N e ls o n , e t a l .
(1 9 7 0 )
■, r e p o r t e d t h a t g e n e s f o r v e r t i c a l r e s i s ­
t a n c e i n m a iz e n o t o n ly g o v e rn q u a l i t a t i v e r e s i s t a n c e t o some i s o l a t e s
of
THlc.kom2jjOL£>phoLQAia. tuAdica (HelMinthoApofiim tuAclauM) , th e c a u s a l
o rg a n is m o f l e a f b l i g h t d i s e a s e o f m a iz e , b u t a l s o q u a n t i t a t i v e l y c o n ­
d i t i o n t h e am ount o f d i s e a s e .
I t i s a l s o p o s s i b l e t h a t t h e r e a r e p r e s e n t i n t h e s e l i n e s m in o r
e f f e c t g e n e s t h a t , when c o m b in e d , p ro d u c e a n o b s e r v a b l e i n c r e a s e i n
—6 8 -
re s is ta n c e .
P a rle v lie t
(1 9 7 6 ) r e p o r t e d th e o c c u r r e n c e i n b a r l e y o f
m in o r e f f e c t g e n e s w i t h a d d i t i v e r e s i s t a n c e t o l e a f r u s t
[?UC.CA,yU.CL
haitdoA,) .
L e w e lle n a n d S h a rp (1 9 6 8 ) i n v e s t i g a t e d t h e i n h e r i t a n c e o f m in o r
e f f e c t genes in w heat f o r r e s is ta n c e to s t r i p e r u s t
^aHMAJ)).
(PucasinCcL A&ii-
T h e se g e n e s a r e t e m p e r a t u r e s e n s i t i v e w i t h a g ro u p o f
g e n e s i n t h e v a r i e t y Rego e f f e c t i v e a t a low t e m p e r a t u r e p r o f i l e and
a n o t h e r g ro u p i n t h e l i n e P . I . 178383 e f f e c t i v e a t a h i g h t e m p e r a t u r e
p ro file .
When t h e s e two g ro u p s o f g e n e s a r e com bined t h e r e i s an
a d d i t i v e i n t e r a c t i o n r e s u l t i n g i n g r e a t e r r e s i s t a n c e a t b o th te m p e r­
a tu re p r o f ile s .
S h a rp , e t a l .
( 1 9 7 6 ) , showed t h a t v a r i e t i e s o f w h e a t s u s c e p t i b l e
t o s t r i p r u s t c o u ld b e c r o s s e d a n d , a f t e r s e v e r a l g e n e r a t i o n s o f s e l ­
e c t i o n , p ro d u c e p ro g e n y w i t h h i g h l e v e l s o f r e s i s t a n c e .
S in c e a d d i t i v e r e s i s t a n c e h a s b e e n shown t o r e s u l t fro m t h e com­
b i n a t i o n o f g e n e s w i t h b o t h m a jo r a n d m in o r e f f e c t s , and s i n c e i t h a s
b e e n shown t h a t s u s c e p t i b l e l i n e s c a n b e com bined t o p ro d u c e r e s i s ­
t a n t p ro g en y , i t
i s d e s ir a b le to i n v e s t i g a t e f u r t h e r th e p o s s i b i l i t y
o f a d d it iv e r e s i s t a n c e to P.
in b a rle y .
T a b le 5 - 1 .
R e a c ti o n s o f
p o p u la tio n s t e s t e d to d i f f e r e n t i s o l a t e s o f P.
F2 r e a c t i o n 1
P o ssib le
R es.
Susc.
G en e M o d e l
C hi
Square
V alue
no
3 96
4
t h r e e d om inant g e n e s
sa m e g e n e
.5 0 —
.3 0
n o F1
209
2
t h r e e dom inant g e n e s
sa m e g e n e
.5 0 —
.3 0
no F
2 78
17
tw o d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
.7 5 .5 0 -
.7 0
.3 0
no F
299
8
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
.7 0 -
.5 0
F1 ; i
316
3
sa m e g e n e
t h r e e d om inant gen es
— ——
n o F1
93
3
sa m e g e n e
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
tw o o r t h r e e d o m i n a n t g e n e s
— ——
same g e n e
—
C ross
reactio n
C rosses te s te d
T ifa n g
to P t T -I
( I ) 2 x C .I.
(1 ,2 )
9819 ( 1 .2 )
C .I.
9819
C .I.
9819 ( 1 , 2 ) x C . I .
x T ifan g
C .I.
9819 ( I )
x C .I.
U n itan (1 ,2 ) x C .I .
S tep to e
C .I.
(1 ,2 )
(I)
2235 ( 1 , 2 , 3 )
2235 ( 1 ,2 )
9776 ( I )
(1 ,2 ) x C .I.
5791
tQAU.
9776 ( I )
x S tep to e
(I)
FV 1
C .I.
7584 ( I )
x U n itan
(1 ,2 )
FV 1
C .I.
2235 ( I )
x T ifan g
(I)
n o F1
C rosses te s te d
—
.5 0 .50 .2 5 -
.3 0
.30
.20
3 94
O
3 35
O
sa m e g e n e
—
I
sa m e g e n e
t h r e e d om inant g e n e s
————
.7 0 -
.50
96
to P t 8
T ifa n g
(1 ,2 ) x C .I .
7584 ( 1 . 2 )
no F
1 44
8
tw o d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
.7 0 .7 0 -
.50
.50
T ifan g
(2 ,1 )
7584
(1 ,2 )
no F1
2 95
13
tw o d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
.2 0 .7 5 -
.10
.70
x C .I.
C .I.
7584
(2 ,1 )
x T ifan g
(2 ,1 )
n o F1
3 45
35
tw o d o m i n a n t g e n e s
.025 -
C .I.
7584
(2 ,1 )
x T ifan g
(1 ,2 )
n o F1
3 69
18
two d o m i n a n t g e n e s
two d o m i n a n t , o n e r e c e s s i v e g e n e
. 2 0 - . .10
. 9 9 - ..9 5
R e actio n ty p e s I ,
^ P aren tal re a c tio n
2 and 3 c o n s id e re d
ty p es
r e s is ta n t, reactio n
in p aren th ese s.
type 4 c o n s id e re d s u s c e p tib le .
.01
Table 5-1
(con t.)
reactio n
C ross
C rosses te s te d
F£ r e a c t i o n
P o ssib le
R es.
Susc.
G en e M o d e l
Chi
Square
V alue
96
264
one r e c e s s i v e gene
.5 0 -
.30
one r e c e s s iv e gene
.8 0 -
.75
. 80 -
.75
t o P t 10
B e tz es
( 4 ) x Hypana ( - )
n o F^
B e tz e s
(4 ) x Hypana
(2)
F1 ; 1 , 2 , 4
1 05
305
B e tz es
(4) x U n lta n
(1 ,2 )
F1 ; 1 , 2
3 42
82
one re c e s s iv e ,
T lfan g
(2 ,3 ) x C .I .
5791 ( 3 , 2 )
n o F^
1 69
59
one do m in an t gene
. 80 -
.75
63
2
sa m e g e n e
t h r e e dom in an t genes
two d o m i n a n t g e n e s
—
.5 0 .3 0 -
.30
.2 5
. 2 0 - , .10
C .I.
7584 ( - ) x C . I .
C rosses te s te d
C .I.
9776 ( I )
5791 ( - )
no F
one dom in an t gene
t o Mt 7 7 - 1
x G eorgie
(4 ,3 )
Fl : 1
F1 ; 1 , 2
196
80
one d o m inant gene
one d o m in a n t,
1 59
26
n o F1
207
3
2235 ( 1 , 2 )
no F
3 96
19
2235 ( 1 , 2 )
n o F^
301
3
sa m e g e n e
t h r e e dom inant genes
7584 ( 2 , 1 ) x C . I .
9819 ( I )
no F
203
7
tw o d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
C .I.
9819 ( 1 , 2 )
1197
no F
3 09
67
C .I.
9819 ( 1 , 2 ) x S t e p to e
3 94
0
B e tz es
(4) x S te p to e
(1 ,2 )
C .I.
9819 ( 1 ,2 ) x C . I .
5791
C .I.
9819 ( 1 , 2 ) x C . I .
C .I.
9819
C .I.
(1 ,2 )
x C .I.
(1 ,2 )
1
T ifan g
x C .I.
(4) x G eo rg ia
(4)
(2 ,1 )
(1 ,2 )
rv
1
V
4
25
158
two r e c e s s i v e g e n e s
.995 -
.990
sa m e g e n e
t h r e e d om inant gen es
————
.9 0 -
., 8 0
tw o d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e gene
.2 0 .9 5 -
., 1 0
. 90
.5 0 -
., 3 0
.10
.5 0 -
. 05
..3 0
o ne d o m i n a n t , o ne r e c e s s i v e gene
.7 0 -
,. 5 0
sa m e g e n e
—
b o th p a r e n ts s u s c e p tib le
—-----
Tabic 5-1
(cen t.)
C rosses re s te d
9819
C . I . 5791
C .I.
C .I.
C .I.
R es.
Susc.
G en e M o d e l
1 ,2 ,3
(1 ,2 )
(I)
3 28
105
1 ,2
348
36
207
6
x F irlb ec k s
x G eo rg ia
5791 ( 1 , 2 )
F irlb ec k s
III
(I)
x U n itan
5791
(I)
C .I.
9819
(1 ,2 )
III
(4 ,2 ,3 )
(1 ,2 )
(3 ,4 )
.7 5 -
tw o d o m i n a n t g e n e s
.0 2 5 -
sa m e g e n e
t h r e e dom in an t genes
tw o d o m i n a n t , o n e r e c e s s i v e
gene
.2 0 .2 0 -
I
376
0
sa m e g e n e
—
I
80
0
sa m e g e n e
—
.7 0
.0 1
.1 0
.1 0
fV
fV
fV
1 ,2
1 63
13
tw o d o m i n a n t g e n e s
.7 0 -
.5 0
2 .3
2 65
18
tw o d o m i n a n t g e n e s
.9 5 -
.9 0
I
191
I
sa m e g e n e
—
FV
FV
FV
1 .2
386
37
tw o d o m i n a n t g e n e s
.0 5 -
.0 2 5
1 ,2 ,3
348
42
one d om inant,
.1 0 -
.0 5
3 ,2
209
1 82
b o th p a re n ts
FV
fV
fV
I
210
13
47
254
I
119
3
t h r e e dom inant genes
same g en e
.5 0 -
fV
FV
I
2 42
0
same g e n e
—
3 ,2 ,4
2 16
155
b o th p a re n ts su s c e p tib le
—
H
I
(3 ,4 )
III
III
(4 ,3 )
(3 ,4 )
two r e c e s s i v e
su scep tib le
genes
—
t o Mt 7 7 - 6
(4) x G eo rg ie
G eorgie
III
x F irlb ec k s
T ifan g
(I)
(1 ,2 )
(1 ,2 )
x F irlb ec k s
B e tz es
7584
Fl :
(1 ,2 )
X F irlb e c k s
C rosses te s te d
F irlb ec k s
(1 ,2 )
1 .2
one dom inant gene
t o Mt 7 7 - 5 1
C .I.
(4 ,3 )
fV
(4 ,2 ,3 ) x S tep to e
C rosses te s te d
T ifan g
(I)
FV
FV
fV
t o Mt 7 7 - 3
Hypana ( 4 ) x U n i t a n
T ifan g
(3 ,2 ,4 )
(1 ,2 )
x S tep to e
X U n itan
III
(4 ,3 )
x U n itan
5791 ( 1 , 2 )
9819 ( I )
Chi
Square
V alue
t o Mt 7 7 - 2
C rosses te s te d
C.I.
P o ssib le
reactio n
C ross
C.I.
F£ r e a c t i o n
x S tep to e
(I)
(3 ,4 )
x S tep to e
x U n itan
(I)
( 1 .2 )
x F irlb ec k s
III
(4 ,3 )
3 ,2
tw o d o m i n a n t g e n e s
.9 0 -
b o th p a r e n ts
—
su scep tib le
.8 0
.3 0
Table 5 -1
(cont.)
reactio n
C ross
C rosses te s te d
9776
(1 ,3 ,2 )
C .I.
9776 ( - ) x F i r l b e c k s
C .I.
7584
C rosses te s te d
R es.
Susc.
Cene Model
Chi
Snuare
''a lu e
(3 ,4 ,2 )
III
(-)
(4 ,3 ,2 )
no
Fi
70
37
one dom in an t gene
.025 -
t h r e e dom inant g e n e s
tw o d o m i n a n t g e n e s
.2 0 - .1 0
.1 0 - .05
b o th p a re n ts s u s c e p tib le
—
O
sa m e g e n e
—
233
6
t h r e e dom inant g e n e s
sa m e g e n e
179
3
same g e n e
t h r e e dom inant g en es
V
2,1
1 58
5
FV
4 ,3
41
328
.0 1
to Aust I
(I) X C .I.
F irlb ec k s I I I
B estzes
X G eo rg ia
(4) x F irlb e c k s I I I
C rosses te s te d
P o ssib le
t o Mt 7 7 - 7
C .I.
B e tz es
F2 r e a c t i o n
(2 ,4 )
1197 ( I )
x U nitan
no
(1 ,0 )
V-
F1
I
86
.2 5 -
.2 0
.4 5 -
.9 0
t o ELS 7 7 - 6
( 1 ,2 ) x G eorgie
(2 ,3 )
no
F1
C r o s s e s t e s t e d t o Mor I
U n itan
C .I.
C .I.
(2 ,1 ) x C .I.
5791 ( I )
9819 ( I )
S te p to e
(-)
9776 ( I )
x U nitan
x U n itan
x C .I.
9776
(1 ,2 )
(3 ,2 )
(-)
V
no
FV
no
I
F1
I
F1
.7 0
-
.5 0
sa m e g e n e
t h r e e dom inant g e n e s
.2 0
-
.10
tw o d o m i n a n t g e n e s
.9 5 -
.9 0
sa m e g e n e
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
tw o o r t h r e e d o m i n a n t g e n e s
.5 0
.2 5
-
.3 0
.2 0
296
6
t h r e e dom inant gen es
sa m e g e n e
3 25
2
193
13
97
3
Table 5-1
(con t.)
C ross
reactio n
C rosses te s te d
t o Mor I
C .I.
5791 ( I )
7584
(3 ,4 ) x C .I.
x S te p to e
5791
C .I.
7584
(4 ,3 ) x C .I.
9776 ( I )
C .I.
5791
(1 ,2 ) x T ifan g
(3 ,2 )
T ifan g
(4 ,3 ) x C .I.
C .I.
T ifa n g
x C .I.
9819
C .I.
(2 ,3 )
9819 ( 1 ,2 )
9819 ( I )
(3 ,2 )
( - ) x U n itan
340
I
sa m e g e n e
65
7
tw o d o m i n a n t g e n e s
.2 5 -
n o F1
379
6
t h r e e d om inant g e n e s
.9 ° 5 -
no F.
1 95
25
o n e d o m i n a n t , tw o r e c e s s i v e
V
2
305
90
one d om inant gene
.5 0 -
.3 0
no F i
200
51
one d o m inant gene
.1 0 -
. 0 5
no F1
429
0
sa m e g e n e
n o F1
228
2
sa m e g e n e
t h r e e d om inant gen es
.5 0 -
.3 0
same g e n e
—
o n e d o m i n a n t , tw o r e c e s s i v e g e n e s
.2 0 -
.1 0
genes
.2 5 -
.2 0
.9 9 0
.2 0
286
I
F1 ; 2 ,1
361
51
303
29
tw o d o m in a n t g e n e s
.0 5 -
.025
368
50
o n e d o m i n a n t , tw o r e c e s s i v e g e n e s
.2 5 -
(-)
.2 0
gene
.2 5 -
(4 ,1 ) x U n itan
( 1 ,2 ) x U nitan
(1 ,2 )
.20
.75
.2 5
F1 ; 2 , 1
(I)
U n itan (1 ,2 ,3 ) x S tep to e
FV 2
n o F1
(1 ,2 )
no F
274
9
two d o m i n a n t , o n e r e c e s s i v e
179
8
two d o m i n a n t , o n e r e c e s s i v e g e n e
two d o m i n a n t g e n e s
.8 0 .3 0 -
88
I
sa m e g e n e
t h r e e d om inant genes
—
.7 5 -
i
Y
no F1
CS
rH
T ifa n g
FV 1
n o F^
I—
*
F irlb e c k s I I I
G en e M o d e l
Susc.
t o Mor 15
7584 ( 2 , 3 ) X U n ita n ( 1 , 2 )
B e tz e s
R es.
Chi
S quare
V alue
t o Mor 14
(1 ,2 ) x S tep to e
C rosses te s te d
(3 ,2 )
9776 ( 1 , 2 )
(2 ,3 ,4 ) x C .I.
(2 ,3 )
(1 ,2 )
(4 ,3 )
x F irlb ec k s I I I
C rosses te s te d
C .I.
(2)
9819 ( I ) x T if a n g
T ifa n g
P o ssib le
(c o n t.)
C .I.
T ifan g
F2 r e a c t i o n
Table 5-1
(con t.)
F^ r e a c t i o n
C ross
C rosses te s te d
T ifan g
C .I.
7584 ( 2 , 3 , 1 )
B e tz es
S tep to e
(1 ,2 )
x S tep to e
x S tep to e
x S tep to e
(2 ,3 ,1 ) x C .I.
(2 ,1 )
(2 ,1 )
(2 ,1 )
9776 (4 )
9819 ( 2 , 1 , 3 )
C .I.
9819 ( I ) x C . I .
1197
C .I.
9819 ( I ) x C . I .
5791 ( I )
C .I.
7584 ( 4 , 3 ) x C . I .
C .I.
C .I.
x C .I.
7584 ( 2 ) X T i f a n g
(1 ,2 )
x C .I.
7584 ( 4 , 3 )
U n itan (1 ,2 )
B e tz es
(2 ,3 )
9819
(I)
(2)
1197
(2 ,1 )
9776 (4 )
(4 ) x Hypana ( - )
(-)
(4)
7584 ( 2 , 3 , 4 )
x C .I.
x C .I.
9776
B e tz e s ( 4 , 3 , 1 ) x Hypana (4 )
B e tz es
R es.
Gene M o d e l
x F irlb ec k s
III
59
no F
(2 ,3 )
C .I.
T ifan g
P o ssib le
Susc.
Chi
Square
V alue
t o Mor 1 5 ( c o n t . )
(I) x S tep to e
C . 1 . 9819 ( I )
F2 r e a c t i o n
n o F,
211
F1 ; i
400
20
F1 ; 2 , 3 , 4
164
7
23
29
71
130
213
n o F^
103
n o F1
n o F1
fV
V
4
4
two d o m i n a n t g e n e s
o n e d o m i n a n t , two r e c e s s i v e
genes
.5 0 .3 0 -
.30
.2 5
o n e d o m i n a n t , two r e c e s s i v e g e n e s
.1 0 -
.0 5
gene
.9 5 .2 5 -
.90
.2 0
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
two d o m i n a n t g e n e s
.75 .2 5 -
.70
.20
tw o d o m i n a n t , o n e r e c e s s i v e
two d o m i n a n t g e n e s
one r e c e s s i v e gene
.5 0 -
.30
two r e c e s s i v e g e n e s
.05 -
,. 0 2 5
0
sa m e g e n e
—
323
0
sa m e g e n e
—
254
16
two d o m i n a n t g e n e s
two d o m i n a n t , o n e r e c e s s i v e
gene
.9 0 .5 0 -
.8 0
.30
n o F1
391
28
two d o m i n a n t g e n e s
.75 -
,. 7 0
no F
145
23
o n e d o m i n a n t , two r e c e s s i v e
one d o m in a n t, one r e c e s s i v e
genes
gene
.95 .1 0 -
.9 0
.0 5
no F
67
11
o n e d o m i n a n t , two r e c e s s i v e
one d o m in a n t, one r e c e s s i v e
genes
gene
.9 9 5 - .990
. 3 0 - .2 5
188
92
one d om inant gene
96
264
one r e c e s s i v e gene
.5 0 -
.30
62
243
one r e c e s s i v e
.1 0 -
.0 5
fV 2
no F1
F1 ; 4 ,3
(-)
6
V
1
gene
one dom inant gene
l e s s th an
.0 2 5 -
.0 0 5
.01
Table 5-1
(cen t.)
C ross
C rosses te s te d
T ifan g
P o ssib le
reactio n
R es.
Susc.
G en e M o d e l
Chi
Square
V alue
n o F^
1 32
124
tw o r e c e s s i v e g e n e s
.0 2 5 -
F1 ; 3 , 2
2 32
18
tw o d o m i n a n t g e n e s
.7 0 -
.5 0
no F 1
2 99
83
one dom inant gene
.2 0 -
.1 0
no F1
3 25
I
sa m e g e n e
—
F1 ; 1 , 4
2 31
20
two d o m i n a n t g e n e s
.3 0 -
.2 5
tw o r e c e s s i v e g e n e s
t o Mor 18
(2) x C .I .
9776
C .I.
9776 ( 4 , 3 )
C .I.
7584 ( I )
x C .I.
C .I.
7584 ( I )
x S tep to e
B e tz es
F£ r e a c t i o n
(1 ,3 ,2 )
(4 ,3 )
x F irlb ec k s
III
(1 ,3 ,2 )
9776 ( 3 ,4 )
(1 ,2 )
x F irlb e c k s I I I
( I . 4 ,3 ,2 )
.0 1
B e tz e s
( 1 , 2 , 3 ) x Hypana (4 )
F1 ; 3 ,2
150
256
.01 -
.005
B e tz es
(I)
n o F1
388
5
sa m e g e n e
t h r e e d om inant g e n e s
.7 0 -
.5 0
O
sa m e g e n e
-------- ---
(2 ,1 )
F1 ; 2 , 1
C .I.
7584 ( 1 , 2 )
x C .I.
1197 ( 1 , 2 )
n o F1
86
O
same g e n e
—
C .I.
7584 ( 1 , 2 )
x C .I.
5791 ( I )
n o F1
55
O
sa m e g e n e
—
(1 ,2 )
F1 ; 1 , 2
256
O
sa m e g e n e
—
F1 ; 1 ,2
393
41
two d o m i n a n t g e n e s
.0 1 -
.005
F1 ; 1 , 2
379
33
two d o m i n a n t g e n e s
.2 0 -
.10
219
86
one dom in an t gene
.2 0 -
.10
.2 0 -
.1 0
.2 5 -
.2 0
U n itan
(2 ,1 )
(2 ,1 )
CM
B e tz e s
x U n itan
(1 ,2 )
x S tep to e
x S tep to e
C rosses te s te d
C .I.
5791 ( I )
C .I.
9819
to P t R
x F irlb eck s
(1 ,2 )
x Hypana
Hypana (4 ) x U n i t a n
Hypana ( 4 , 2 , 3 )
C .I.
7584 ( I )
III
(3 ,4 )
x S tep to e
(4) x C . I .
T ifa n g
(3 ,2 )
(I)
7584 ( 2 , 4 , 3 )
x C .I.
7584 ( 2 , 4 , 3 )
(3 ,4 )
(2 ,1 )
x Hypana ( 4 , 3 )
T ifa n g
C .I.
263
7584 ( 2 , 1 )
x T ifa n g (4)
F1 ; 2 , 1
fV 1
n o F1
no F
Fi ; 4
302
27
two d o m i n a n t g e n e s
287
55
one d o m in a n t, one r e c e s s i v e
99
204
130
24
72
304
one r e c e s s i v e gene
one d o m in a n t, one r e c e s s i v e
one r e c e s s i v e gene
gene
less
gene
than
.005
.5 0 -
.30
.01 -
.005
Table 5-1
(cen t.)
F„ r e a c t i o n
P o ssib le
R es.
Susc.
G en e M o d e l
346
58
one d o m in a n t, one r e c e s s i v e
65
25
one d om inant gene
2 09
198
one d om inant gene
less
2 ,3 ,4 ,1
2 40
149
one dom inant gene
less
4
137
206
tw o r e c e s s i v e g e n e s
.2 0 -
10
19
73
one r e c e s s i v e gene
.2 5 -
20
206
0
sa m e g e n e
—
HO
0
sa m e g e n e
—
158
0
sa m e g e n e
—
233
0
sa m e g e n e
—
151
0
sa m e g e n e
—
1 41
68
one dom inant gene
.0 2 5 -
1 55
0
sa m e g e n e
—
I
152
2
sa m e g e n e
t h r e e d om inant gen es
.8 0 -
75
I
363
37
tw o d o m in a n t g e n e s
.0 2 5 -
.0 1
177
59
one dom inant gene
1 .0 0 0
207
0
same g e n e
—
F^ r e a c t i o n
C ross
Chi
Square
V alue
Crosses tested to Pt R (cone.)
C .I.
7584 ( 1 , 2 )
x T ifan g
(2 ,3 )
no
C .I.
2235 ( 2 , 3 )
x T ifan g
(3 ,4 ,2 )
no
G eorgia
(4 ,3 )
x U n itan
G eorgia
(4 ,3 )
x S tep to e
(1 ,2 )
(1 ,2 )
C .I.
7584 ( 1 , 2 ) x G e o r g ia
C .I.
2235
(4 ,3 )
C rosses te s te d
T ifan g
(1 ,0 )
x T ifan g
F1 :
FV
fV
(4)
no
(4)
F1
F1
4 ,3
F1
gene
.0 2 5 -
.01
.7 0 -
50
th an
005
th an
0 05
t o P t S-2
x C .I.
2330 ( 1 , 2 )
no
no
"
(1 ,2 ) x C .I.
4544
"
(1 ,0 )
7584 ( 1 , 2 )
FV
no
x C .I.
(2 ,1 ,3 )
"
(1 ,0 )
x C .I.
9819 ( 2 , 1 , 3 )
"
(1 ,0 )
x C .I.
9776
"
(2 ,4 )
x C .I.
9776 ( 1 , 2 )
"
(I)
x U n itan
"
(I)
x S tep to e
"
(1 ,2 ,3 )
"
(2 ,3 ) x C .I.
5791
(2 ,1 )
FV
no
"
(1 ,0 )
5791
(2 ,1 )
no
(0 ,1 )
(I)
Fl :
(I)
FV
x F irlb ec k s
x C .I.
Fl :
no
III
(3 ,2 ,4 )
F1
F1
1 .2
F1
0 ,1
F1
I
F1
F1
.01
Table 5-1
(con t.)
C ross
F irlb ec k s
G eorgie
U n itan
III
(-)
Co P t S - 2
x U nitan
(2, I) x S te p to e
Susc.
G en e M o d e l
F1 ; 2 , 3
2 23
22
two d o m i n a n t g e n e s
.1 0 -
.05
F1 ; 1 , 2
312
1 00
one d om inant gene
.7 5 -
.7 0
9819 ( 1 , 2 ) x U n i t a n
x U n itan
Hypana ( 4 , 2) x U n ita n
G eorgia
377
O
sa m e g e n e
440
O
sa m e g e n e
F1 ; 1 , 2
220
2
sa m e g e n e
t h r e e d o m inant gen es
.9 0 -
.80
F1 ; 3 ,2
245
19
tw o d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
.7 0 .1 0 -
.50
.05
(1 ,2 )
n o F1
327
O
sa m e g e n e
—
(I)
F1 ; 1 ,2
384
17
two d o m i n a n t , o n e r e c e s s i v e
tw o d o m i n a n t g e n e s
gene
.7 0 .1 0 -
.5 0
.05
365
11
tw o d o m i n a n t , o n e r e c e s s i v e
gene
.2 0 -
.1 0
FV 1
F1 ; 1 . 2
406
26
two d o m i n a n t g e n e s
tw o d o m i n a n t , o n e r e c e s s i v e
gene
.9 0 .2 0 -
.8 0
.1 0
no F1
413
same g e n e
t h r e e dom inant genes
.5 0 -
.3 0
.7 0 .2 0 -
.5 0
.1 0
.8 0
(1 ,2 )
C .I.
7584 ( I )
(I)
(I)
5791 ( I )
F1 ; 1 , 2
(I)
V 1
(1 ,3 ,2 )
(1 ,2 )
x S tep to e
(4i , 3 ) x S t e p t o e
Hypana ( I , 3 ,2 ) x S t e p t o e
C .I.
R es.
Chi
Square
V alue
(c o n t.)
(4 ,3 ) x U n itan
C .I.
C .I.
P o ssib le
re a c tio n
C rosses te s te d
C .I.
F2 r e a c t i o n
(I)
9819 ( 1 , 2 ) x Hypana ( I , 3 , 2 , 4 )
7584
(2 ,1 ) x C .I.
9776 ( 1 , 2 )
9819 ( 2 , 1 )
n o F1
. 238
10
tw o d o m i n a n t , o n e r e c e s s i v e g e n e
tw o d o m i n a n t g e n e s
9776 ( I )
n o F1
194
12
tw o d o m i n a n t g e n e s
.9 0 -
F1 ; 2 , 1
183
0
sa m e g e n e
—
F1 ; 2 , 1 , 3
382
45
one d o m in a n t,
tw o r e c e s s i v e
genes
.0 5 -
.0 2 5
F1 ; 1 , 2 , 3
359
53
o n e d o m i n a n t , tw o r e c e s s i v e
genes
.5 0 -
.3 0
F1 ; 2 , 1
3 74
10
t h r e e dom inant g e n e s
two d o m i n a n t , o n e r e c e s s i v e g e n e
.2 0 .1 0 -
.1 0
.0 5
C .I.
7584
C .I.
9819 ( 2 , 1 )
C .I.
9819 ( 2 , 1 ) x C . I .
C .I.
5791
(I) x F irlb ec k s I I I
(3 ,2 ,4 )
C .I.
9819
(I)
(2 ,3 )
C .I.
5791 ( I )
(1 ,2 ) x C .I.
x C .I.
1197 ( 2 , 1 )
x F irlb ec k s I I I
x G eo rg ia
4
—
(3 ,2 ,4 )
Table 5-1
(cen t.)
C ross
reactio n
F£ r e a c t i o n
P o ssib le
R es.
G en e M o d e l
Susc.
Chi
Square
V alue
C ro ss e s to Pt S -2 (c o n e .)
x G eorgie
(4 ,3 ,2 )
C .I.
7584
C .I.
7584 ( I ) X H ypana ( 3 , 2 , 1 , 4 )
C .I.
75 84
C .I.
9819 ( I ) x G e o r g i a
C .I.
9776 ( I )
X Hypana
C .I.
75 84
X F irlb ec k s
U)
(2 ,1 )
(I)
x C . I . 5791
(2 ,3 ,1 )
F ; I
343
17
two d o m i n a n t , o n e r e c e s s i v e
tw o d o m i n a n t g e n e s
F ; I
3 29
9
t h r e e dom inant genes
two d o m i n a n t , o n e r e c e s s i v e
one d o m in an t gene
one d o m in a n t, one r e c e s s i v e
(4 ,2 ,3 )
(-)
F .;
III
71
no F
22
gene
.9 9 .25 -
.95
.2 0
gene
.2 0 .1 0 -
.1 0
.0 5
gene
.8 0 .2 5 -
.7 5
.2 0
1 ,2
1 20
40
one dom inant gene
1 .0 0 0
I
250
48
o n e d o m i n a n t , two r e c e s s i v e g e n e s
one d o m in a n t, one r e c e s s i v e gene
.5 0 .2 5 -
.30
. 20
77
21
one d o m in a n t gene
one d o m in a n t, one r e c e s s i v e
.5 0 .5 0 -
.30
.3 0
( 4 , 2 , 3 , I ) F ; 1 ,2
gene
-79-
T a b le 5 - 2 .
B a r le y l i n e s w i t h p o s s i b l e g e n e s i n common.
G enes i n common f o r t h r e e i s o l a t e s
C ro s s
U n ita n x S t e p to e
C . I . 5791 x U n ita n
C . I . 5791 x S t e p to e
T if a n g x C . I . 9819
Pt
Pt
Pt
Pt
S -2
S -2
T -I
T -I
Is o la te s
Mor 15
Mor I
Mor I
Mor I
Moi : 18
Mt 7 7 -2
Mt 7 7 -2
P t S -2
G enes i n common f o r two i s o l a t e s
C ro s s
C . I . 7584 x U n ita n
C . I . 7584 x S t e p to e
C . I . 7584 x C . I . 1197
C . I . 9819 x C . I . 1197
C . I . 9819 x C . I . 5791
C . I . 7584 x C . I . 5791
C . I . 9819 x U n ita n
T if a n g x U n ita n
T if a n g x S t e p to e
S t e p to e x C . I . 9776
U n ita n x C . I . 9776
Is o la te s
P t T -I
Mt 7 7 -6
P t S-2
Mor 18
A u st I
Mor 18
P t 10
Mor 15
Mor 15
Mt 7 7 -1
P t 10
Mor 18
P t S -2
Mt 7 7 -2
P t S-2
Mt 7 7 -3
P t S-2
Mt 7 7 -6
Mor I
P t T -I
Mor I
P t T -I
G enes i n common f o r o n e i s o l a t e
C ro s s
T if a n g x C . I . 2330
T if a n g x G . I . 4544
T if a n g x C . I . 7584
T if a n g x C . I . 2235
C . I . 9819
x S t e p to e .
B e tz e s x S t e p to e .
B e tz e s x U n ita n
B e tz e s x G e o fg ie
'
C . I . 7584
x C . I . 9776
F irlb e c k s
I I I x U n ita n
Is o la te
P t S-2
P t S-2
P t S-2
P t T -I
Mt 77-1
Mor 18
Mor 18
ELS 77-6
P t S-2
A u st I
-
T a b le 5 - 3 .
8
0
-
P o s s i b l e n um bers o f g e n e s f o r r e s i s t a n c e i n e a c h l i n e .
B a r le y l i n e
S te p to e ■
U n ita ri
C . I . 9819
C . I . 5791
T if a n g
C . I . 1197
C . I . 9776
C . I . 7584
C . I . 2235
C . I . 4544.
C . I . 2330
B e tz e s
F irlb e c k s I I I
G e o rg ie
T a b le 5 - 4 .
Number o f g e n e s
3
3
3
3
2
2
2
2
I
I
I
I
I
I
E f fe c t o f s u s c e p tib le p a re n ts o f e x p re s s io n o f r e s i s ta n c e .
re a c tio n
C ro s s
F9 r e a c t i o n
R*2
S
H ypana ( 4 )^ x U n ita n ( 2 ,1 )
G e o rg ia ( 4 ,3 ) x U n ita n ( 1 ,2 )
4 ,2
4 ,3
219
209
86
198
H ypana ( 4 , 2 , 3 ) x S t e p to e ( I )
G e o rg ie ( 4 ,3 ) x S t e p to e ( 1 ,2 )
2 ,1
2 ,3 ,4 ,I
302
240
27
149
C . I . 7584 ( I ) x H ypana ( 4 ,3 )
C . I . 7584 ( 1 ,2 ) x G e o rg ia (4 )
I
4
287
137
55
206
^ A ll c r o s s e s t e s t e d t o P t R.
2
R; num ber o f r e s i s t a n t p l a n t s .
S ; num ber o f s u s c e p t i b l e p l a n t s .
3
P a re n ta l re a c tio n s in p a re n th e s e s .
T a b le 5 - 5 .
E v id e n c e f o r a d d i t i v e r e s i s t a n c e t o P .
toJitlA.
re a c tio n
C ro ss.
F^ r e a c t i o n ty p e
1
T if a n g (4 )
B e tz e s
I
, .
x G e o rg ia (4 )
(4 ) x G e o r g ia ( 3 ,4 )
G e o rg ie ( 3 ,4 ) x F i r l b e c k s I I I
B e tz e s
(4 ) x F i r l b e c k s I I I
T if a n g
( 4 ,3 ) x F i r l b e c k s I I I
( 4 ,3 )
( 4 ,3 ,2 )
( 3 ,4 )
2
3
4
6
18
158
Mt 7 7 -1
4
I
3 ,2
O
7
40
254
■ Mt 7 7 -6
25
65
126
155
Mt 7 7 -6
328
Mt 77-7
.182
Mt 7 7 -5 1
3 ,2 ,4
4 ,3
O
13
3 ,2
4
69
P a r e n ta l r e a c ti o n ty p e in p a r e n th e s e s .
I n d i c a t e s num ber o f
. 2
Is o la te
p la n ts in each r e a c tio n ty p e .
28 .
136
DISCUSSION
I n a l l i n o c u l a t i o n t e s t s p e rfo rm e d i n t h i s s t u d y , s u s p e n s io n s o f
c o n i d i a w e re u s e d a s in o c u lu m .
In o rd e r to o b ta in s a ti s f a c to r y in ­
f e c t i o n and d i s e a s e d e v e lo p m e n t, a d e q u a te c o n c e n t r a t i o n s o f c o n id i a
i n t h e i n o c u l a w e re n e c e s s a r y .
For t h i s r e a s o n , th e e f f e c t s o f d i f ­
f e r e n t t y p e s o f g ro w th m ed ia and d i f f e r e n t p h o t o p e r i o d s on t h e s p o r u l a t i o n o f P.
w e re s t u d i e d .
I t w as fo u n d t h a t d i f f e r e n t t y p e s o f g ro w th m ed ia d i f f e r e d s i g ­
n i f i c a n t l y i n t h e i r e f f e c t on t h e s p e c u l a t i o n o f P . -£eA&4.
Four d i f ­
f e r e n t a g a r t y p e s ; lim a b e a n a g a r , V8 j u i c e a g a r , M y c o p h il a g a r and
b a r l e y l e a f e x t r a c t a g a r w e re a l l fo u n d t o a llo w a b u n d a n t s p q r u l a t i o n
o f P.
tQAU.
A c o n s i s t e n t i n c r e a s e i n s p o r u l a t i o n was o b s e rv e d i n r e s p o n s e
to d e c re a s in g p h o to p e rio d s .
A p h o t o p e r i o d o f 8 h o u r s w as found to
c a u s e s i g n i f i c a n t l y g r e a t e r s p o r u l a t i o n th a n any o t h e r p h o to p e r io d
te s te d .
E x c e p t f o r a c o n d i t i o n o f no l i g h t , no p h o t o p e r i o d s o f l e s s
th a n 8 h o u r s w e re t e s t e d .
B e c a u se o f t h e o b s e rv e d i n c r e a s e i n s p o r ­
u l a t i o n w i t h d e c r e a s i n g p h o t o p e r i o d s , t h e e f f e c t on s p o r u l a t i o n o f
e v e n s h o r t e r p h o t o p e r i o d s s h o u ld be i n v e s t i g a t e d .
The w ork o f O n e s ir o s a n an d B a n t t a r i (1969) i n d i c a t e s t h a t th e
f o r m a ti o n o f c o n id i o p h o r e s r e q u i r e s u l t r a v i o l e t l i g h t i n t h e r e g i o n
o f 3 1 0 -3 5 5 pm, an d t h e s u b s e q u e n t p r o d u c t i o n o f c o n i d i a was n o t d e ­
p e n d e n t on l i g h t .
From t h i s i n f o r m a t i o n , and t h e i n f o r m a t i o n i n t h e
p r e s e n t s t u d y , i t w ould a p p e a r t h a t t h e maximum s p o r u l a t i o n o f P.
-83-
m ig h t p o s s i b l y b e o b t a i n e d by g ro w in g th e c u l t u r e s u n d e r u l t r a v i o l e t
l i g h t i n t h e 3 1 0 -3 5 5 pm r e g i o n , w i t h o u t l i g h t o f l o n g e r w a v e le n g th s .
By c u l t u r i n g i s o l a t e s o f P .
tQJKZA on V8 j u i c e a g a r , u n d e r an 8
h o u r p h o t o p e r i o d , a d e q u a te s p o r u l a t i o n was o b t a i n e d t o p ro d u c e i n o c u l a
w i t h s p o r e c o n c e n t r a t i o n s h ig h en o u g h to p ro d u c e r e a d a b l e , d i f f e r e n ­
t i a t i n g sym ptom s on h o s t t i s s u e .
w e re u s e d i n t h e c u l t u r i n g o f P.
B e c a u se o f t h i s , t h e s e c o n i d i t i o n s
teAZA f o r a l l s u b s e q u e n t i n o c u l a t i o n s .
A c o l l e c t i o n o f t w e n t y - s i x i s o l a t e s o f P.
, f i f t e e n from t h e
M id d le E a s t and e le v e n fro m t h e s t a t e o f M o n tan a, was d i v i d e d i n t o d i f ­
f e r e n t v i r u l e n c e t y p e s , b a s e d on t h e d i f f e r e n t i a l r e a c t i o n s o f . d i f f e r e n t
b a r l e y l i n e s and v a r i e t i e s .
The M id d le E a s t i s o l a t e s w ere fo u n d to
d i f f e r s i g n i f i c a n t l y fro m th e M ontana i s o l a t e s .
V a r ie tie s s u s c e p tib le
to a l l e le v e n M ontana i s o l a t e s , s u c h a s F i r l b e c k s I I I , B e t z e s , S h a b e t
and I n g r i d , w ere r e s i s t a n t to s e v e r a l M id d le E a s t e r n i s o l a t e s .
A ls o ,
some b a r l e y l i n e s r e s i s t a n t t o a l l t h e M ontana i s o l a t e s , s u c h a s C . I .
7584 a n d C . I . 9 7 7 6 , w e re s u s c e p t i b l e t o some M id d le E a s t e r n i s o l a t e s .
The M id d le E a s t i s o l a t e s s e p a r a t e d i n t o s e v e n d i f f e r e n t v i r u l e n c e
t y p e s , b a s e d on t h e d i f f e r e n t i a l r e a c t i o n s o f tw e lv e b a r l e y l i n e s .
The
M ontana i s o l a t e s s e p a r a t e d i n t o f i v e d i f f e r e n t v i r u l e n c e t y p e s , u s in g
e ig h t d if f e r e n t b a rle y lin e s .
The p r im a r y p u r p o s e o f t h i s w ork was t o o b t a i n i s o l a t e s r e p r e s e n t a ­
t i v e o f t h e e n t i r e c o l l e c t i o n w h ic h c o u ld b e u s e d i n s c r e e n in g b a r l e y
l i n e s f o r r e s i s t a n c e t o P.
tQAU .
I t was hoped t h a t t h e u s e o f i s o l a t e s
—8 4 —
r e p r e s e n t i n g d i f f e r e n t v i r u l e n c e t y p e s w ould a i d i n f i n d i n g s o u r c e s o f
b r o a d b a s e d r e s i s t a n c e e f f e c t i v e a g a i n s t a w id e r a n g e o f v i r u l e n c e t y p e s
o f t h i s o r g a n is m .
T h is w ork i s n o t c o n s id e r e d a f i n a l c o n c lu s i o n t o t h e d i f f e r e n t
v i r u l e n c e t y p e s o f P.
tojidb.
W ith t h e a d d i t i o n o f m ore i s o l a t e s fro m
d i f f e r e n t a r e a s , o t h e r t y p e s o f v i r u l e n c e w i l l m o st l i k e l y be f o u n d .
W ith f u r t h e r t e s t i n g i t may be fo u n d t o b e m ore a p p r o p r i a t e to com bine
'
some s i m i l a r v i r u l e n c e ’ t y p e s o r s e p a r a t e o t h e r s i n t o m ore d i s c r i m i n a t ­
in g .g ro u p s .
A s c r e e n i n g p ro g ra m u t i l i z i n g n i n e o f t h e tw e lv e v i r u l e n c e t y p e s was p e rfo rm e d i n w h ic h 147 b a r l e y l i n e s w ere s c r e e n e d f o r r e s i s t a n c e t o
P. toAQA.
T h ese l i n e s c o n s i s t e d p r i m a r i l y o f t h r e e g r o u p s .
One g ro u p
o f 78 l i n e s h a d b e e n r e p o r t e d t o b e r e s i s t a n t t o M oroccan i s o l a t e s o f
P. teAZA ( C a d d e l and W ilc o x s o n , 1 9 7 5 ) .
A s e c o n d g ro u p o f 40 b a r l e y
l i n e s h ad p r e v i o u s l y b e e n r e p o r t e d t o be r e s i s t a n t to N o rth A m erican
is o la te s of
P. td/i 2A (B uchannon a n d M cD onald, 1 9 6 5 ).
The t h i r d g ro u p
c o n s i s t e d o f t w e n t y - t h r e e v a r i e t i e s c o m m e rc ia lly grow n i n M ontana and
n o t p r e v io u s ly sc re e n e d f o r r e s i s t a n c e to
P. -tfcieA .
Of t h e s e 147 b a r l e y l i n e s , n i n e l i n e s w ere .fo u n d t o b e r e s i s ­
t a n t o r i n t e r m e d i a t e i n r e a c t i o n t o a l l n in e v i r u l e n c e t y p e s .
T h ese
l i n e s w e re G .I . 1 6 1 5 , C . I . 4 2 0 7 , C . I . 5 2 9 8 , C . I . 5 4 0 1 , C . I . 5 8 4 5 , C . I .
’
7 2 0 8 , C . I . 9 7 6 8 , C . I . 1 3 2 6 2 , and U n ita n .
An a d d i t i o n a l tw e n ty -tw o
l i n e s w ere fo u n d t o b e r e s i s t a n t o r in te r m e d ia t e , i n r e a c t i o n t o e i g h t
-85-
o f n in e v iru le n c e ty p e s .
T h ese t h i r t y - o n e l i n e s h a v e b e e n c r o s s e d by
D r. H a ro ld B ockelm an i n t o a m ale s t e r i l e
f a c ilita te d
re c u rre n t s e l­
e c t i o n p o p u l a t i o n b e in g d e v e lo p e d f o r r e s i s t a n c e t o n e t b l o t c h , w ith
t h e e x p e c t a t i o n t h a t t h e s e l i n e s w i l l p r o v id e b r o a d - b a s e d r e s i s t a n c e
t o a w id e r a n g e o f v i r u l e n c e ty p e s o f t h i s p a th o g e n .
The l a s t c h a p t e r o f t h i s t h e s i s d e a l s w ith t h e r e a c t i o n s o f
p o p u la tio n s te s te d w ith d i f f e r e n t i s o l a t e s o f
P.
The
g e n e r­
a t i o n s o f 56 d i f f e r e n t c r o s s e s i n v o l v i n g 15 d i f f e r e n t b a r l e y l i n e s
w e re t e s t e d , u s i n g s e v e n te e n d i f f e r e n t i s o l a t e s o f
c r o s s e s w e re t e s t e d t o t h r e e i s o l a t e s .
P. toAdM.
M ost
A t o t a l o f 144 t e s t s w e re
p e rf o r m e d .
I n 44 o f t h e 144 t e s t s , t h e r e s u l t s i n d i c a t e d t h e p a r e n t s o f t h e
c r o s s c o n ta i n e d a common g e n e f o r r e s i s t a n c e t o t h e i s o l a t e u s e d i n
th e t e s t .
T h e se 44 t e s t s in v o lv e d 25 o f t h e 56 d i f f e r e n t c r o s s e s .
The p a r e n t s o f f o u r o f t h e s e 25 c r o s s e s a p p e a r e d t o c o n t a i n a common
g e n e f o r r e s i s t a n c e e f f e c t i v e . a g a i n s t a l l t h r e e i s o l a t e s t o w h ich th e y
w e re t e s t e d .
T h e se c r o s s e s w e re U n ita n x S t e p t o e , C . I . 5791 x U n i t a n ,
C . I . 5791 x S t e p t o e j a n d T if a n g x C . I . 9 8 19.
The p a r e n t s o f e le v e n
c r o s s e s s h a r e common g e n e s e f f e c t i v e a g a i n s t two o f t h e i s o l a t e s t o
w h ic h th e y w e re t e s t e d , and a n a d d i t i o n a l t e n c r o s s e s i n v o lv e p a r e n t s
w h ic h c o n t a i n a common g e n e e f f e c t i v e a g a i n s t one i s o l a t e o f P:
teA b i.
I t i s e v i d e n t t h a t t h e o c c u r r e n c e o f a common g e n e f o r r e s i s t a n c e
b e tw e e n two p a r e n t s o f a c r o s s i s q u i t e f r e q u e n t .
T h is may i n d i c a t e
—8 6 —
t h a t a r e l a t i v e l y few num ber o f r e s i s t a n c e g e n e s a r e r a t h e r u b i q u i t o u s
in b a rle y .
I n a d d i t i o n t o t h e s e , an unknown num ber o f r e l a t i v e l y , un­
common g e n e s f o r r e s i s t a n c e may e x i s t w h ic h a r e u n iq u e t o c e r t a i n l i n e s
and d e r i v a t i v e s o f t h o s e l i n e s .
T h is s tu d y was v e r y b ro a d i n i t s
num ber o f c r o s s e s and. i s o l a t e s .
B e c a u s e o f t h i s , no i n d i v i d u a l l i n e s
o r c r o s s e s w e re e x t e n s i v e l y s t u d i e d .
w e re s t u d i e d .
s c o p e , e n c o m p a s s in g a l a r g e
A ls o , no
l i n e s o f any c r o s s e s
As a r e s u l t , d e f i n i t e i n f o r m a t i o n r e g a r d i n g t h e num ber
o f g e n e s f o r r e s i s t a n c e p r e s e n t i n e a c h l i n e and t h e t o t a l num ber o f
r e s i s t a n c e g e n e s a v a i l a b l e c o u ld n o t b e o b t a i n e d ,
H ow ever, a minimum
num ber o f g e n e s p r e s e n t i n e a c h l i n e a n d a minimum num ber o f g e n e s
a v a i l a b l e c o u ld b e d e te r m in e d .
F o u r b a r l e y l i n e s c o n t a i n a t l e a s t t h r e e d o m in a n t g e n e s , f b u r
l i n e s c o n t a i n a t l e a s t two g e n e s an d s i x l i n e s c o n t a i n a t l e a s t one
gene f o r r e s i s t a n c e !
The f o u r l i n e s c o n t a i n i n g a t l e a s t t h r e e g e n e s a r e S t e p t o e ,
U n i t a n , C . I . 5 7 9 1 , an d C . I . 9 8 1 9 .
Of t h e s e , t h e g e n e s f o r r e s i s t a n c e
i n U n ita n an d S t e p to e may b e t h e sam e.
T h e re i s i n d i r e c t e v id e n c e
t h a t t h e r e s i s t a n c e i n C . I . 5791 i s n o t i d e n t i c a l t o t h a t i n U n ita n
an d S t e p t o e , and a l s o t h e r e s i s t a n c e i n C . I . 9819 i s i d e n t i c a l to
n e i t h e r C . I . 5791 n o r U n ita n an d S t e p t o e .
From t h e i n f e r e n c e s m ade,
a t l e a s t f i v e g e n e s . f o r r e s i s t a n c e s h o u ld b e p r e s e n t among t h e b a r l e y
lin e s .
T h e re i s o n ly a minimum n u m b e r, h o w e v e r, and f u r t h e r t e s t s a r e
-8 7 -
n e c e s s a ry , e s p e c i a l l y in v o lv in g
l i n e s , b e f o r e m ore c o n c l u s i v e i n ­
f o r m a ti o n i s o b t a i n e d .
V a r i a t i o n i n t h e e x p r e s s i o n o f r e s i s t a n c e was o b s e r v e d .
T h is
v a r i a t i o n a p p e a r e d t o b e c a u s e d by b o th t h e e n v iro n m e n t and t h e g e n e t i c
b a c k g ro u n d o f t h e p a r e n t s in v o lv e d i n t h e c r o s s .
I t c o u ld n o t b e
d e te r m in e d w h e th e r t h e h o s t o r t h e p a th o g e n o r b o th w e re a f f e c t e d by
e n v ir o n m e n ta l c h a n g e .
The e f f e c t o f th e g e n e t i c b a c k g ro u n d o f t h e p a r e n t s was m o st
e v i d e n t i n s i t u a t i o n s i n w h ic h o n e r e s i s t a n t l i n e was c r o s s e d w i t h two
s u s c e p tib le l i n e s and th e
same i s o l a t e .
g e n e r a t i o n o f b o th c r o s s e s t e s t e d w i t h t h e
I n c r o s s e s i n v o l v i n g s e v e r a l r e s i s t a n t l i n e s i t was
o b s e rv e d t h a t t h e s u s c e p t i b l e v a r i e t y H ypana a llo w e d a h i g h e r d e g r e e
o f r e s i s t a n c e t o b e e x p r e s s e d i n t h e F^ g e n e r a t i o n t h a n d id th e s u s c e p ­
t i b l e v a r i e t y G e o r g ie .
I n f o r m a t io n o f t h i s ty p e i s e x tr e m e ly v a l u a b l e
when c h o o s in g p a r e n t s , e s p e c i a l l y b a c k c r o s s p a r e n t s , f o r t h e d e v e lo p m e n t
of r e s is ta n t lin e s .
E v id e n c e was fo u n d s u g g e s t i n g t h e o c c u r r e n c e o f a d d i t i v e g en e
a c t i o n i n f i v e c r o s s e s i n v o lv i n g s u s c e p t i b l e p a r e n t s .
A lth o u g h b o th
p a r e n t s e x h i b i t e d s u s c e p t i b l e r e a c t i o n t y p e s , r e s i s t a n t p l a n t s w ere
o b s e rv e d i n t h e F^ g e n e r a t i o n .
I t i s n o t known w h e th e r t h i s a d d i t i v e
r e s i s t a n c e i s t h e r e s u l t o f t h e c o m b in a tio n o f m a jo r g e n e s e f f e c t i v e
a g a i n s t o t h e r i s o l a t e s o r o f m in o r e f f e c t g e n e s .
The im p o r ta n c e i s n o t i n w h e th e r t h e s e g e n e s a r e m a jo r o r m in o r i n
f
-8 8 -
e ffe c t.
I n f a c t , i t i s e n t i r e l y p o s s i b l e t h a t b o th t y p e s a r e in v o lv e d
A ls o , a g e n e f o r r e s i s t a n c e may a c t a s a m a jo r e f f e c t g e n e i n c e r t a i n
s i t u a t i o n s , s u c h a s i n d i f f e r e n t g e n e t i c back g ro u n d s o f th e . h o s t , i n
d i f f e r e n t e n v ir o n m e n ts o r a g a i n s t c e r t a i n i s o l a t e s , w h i l e i n o t h e r
s i t u a t i o n s i t may p r o d u c e o n ly m in o r e f f e c t s .
What i s i m p o r ta n t i s
w h e th e r o r n o t t h e g e n e s a r e in d e e d a d d i t i v e .
I f g e n e s f o r r e s i s t a n c e c a n b e com bined and a c t i n a n a d d i t i v e
m a n n e r, a g e n e r a l ty p e o f r e s i s t a n c e , t h a t i s , a r e s i s t a n c e e f f e c t i v e
a g a i n s t a n e x tr e m e ly w id e r a n g e o f v i r u l e n c e t y p e s o f a p a th o g e n , i s
p o s s ib le .
R e s is ta n c e o f t h i s ty p e i s e s p e c i a l l y d e s ir a b le a g a in s t
o r g a n is m s s u c h a s
VyfltnopkoKa. fczJtzb, s i n c e t h i s o rg a n is m i s e x tr e m e ly
v a r i a b l e a n d o c c u r s i n a l a r g e num ber o f v i r u l e n c e t y p e s .
The o c c u r r e n c e o f t r a n s g r e s s i v e s e g r e g a t i o n and t h e u l t i m a t e
d e v e lo p m e n t o f g e n e r a l r e s i s t a n c e r e s u l t i n g fro m c r o s s e s o f s u s c e p ­
t i b l e v a r i e t i e s w ould b e e x c e p t i o n a l l y v a l u a b l e .
The a b i l i t y t o
u t i l i z e v a r i e t i e s a l r e a d y p o s s e s s i n g c o m m e rc ia lly a c c e p t a b l e a g ro n o m ic
c h a r a c t e r i s t i c s w ould b e a tre m e n d o u s a d v a n ta g e i n a b r e e d i n g p ro g ra m
fo r d is e a s e r e s is ta n c e ,
As s t a t e d e a r l i e r , t h i s s tu d y w as v e r y b ro a d i n i t s
s c o p e and
t h e r e f o r e c o n c l u s i v e d a t a on t h e g e n e t i c s o f r e s i s t a n c e i n b a r l e y to
P.
tOAQA was n o t o b t a i n e d .
T h is b r o a d a p p ro a c h was u s e f u l , h o w e v e r,
i n t h a t i t o p e n e d up a v e n u e s o f s tu d y w h ic h when i n v e s t i g a t e d m ore
e x t e n s i v e l y , s h o u ld p r o v id e v a l u a b l e i n f o r m a t i o n n e e d e d f o r th e .
-8 9 -
d e v e lo p m e n t o f r e s i s t a n c e i n b a r l e y
to PytuiviOpkotiOL to A U .
REFERENCES CITED
REFERENCES CITED
B o c k e lm a n , H . E . , E . L . S h arp and R .F . E s l i c k , 1 9 7 7 .
T riso m lc a n a l y s i s
o f genes f o r r e s i s t a n c e to s c a l d and n e t b l o t c h i n s e v e r a l b a r l e y
c u ltiv a rs.
Can. J . B o t . 5 5 ( 1 5 ) : 2 1 4 2 - 4 8 .
B u c h a n n o n , K.W., an d W.C. M cDonald, 1 9 6 5 .
Sources o f r e s i s t a n c e in
b a r l e y t o VyKOMphoML tOAU. Can. J . P l a n t S c i . 4 5 : 1 9 8 - 1 9 3 .
C a d d e l , J . L . , an d R.D. W i l c o x s o n , 1 9 7 5 .
Sources o f r e s i s t a n c e to n e t
b l o t c h o f b a r l e y i n M orocco.
P i t . D is . R e p t r . 5 9 ( 6 ) :4 9 1 -4 9 4 .
D ick so n , J . G . ,.1 9 5 6 .
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M c G raw -H ill Book Company, I n c . , 517 p p .
Ed. 2. New Y ork,
D r e c h s l e r , C ., 1923.
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APPENDIX
APPENDIX
Recipes of agar types used in sporulation test.
1)
. P o t a t o d e s t r o s e a g a r ( D i f c o ) , Lima b e a n a g a r ( D i f c o ) , C z a p e c k fs a g a r
( D i f c o ) an d M y c o p h il a g a r (BBL) w ere made f o l l o w i n g t h e i n s t r u c t i o n s
on t h e r e s p e c t i v e l a b e l s .
2) V8 j u i c e a g a r :
200 ml C a m p b e lls V8 j u i c e
20 gm B a c t o - a g a r ( D i f c o )
3 gm CaCO^
800 ml D i s t i l l e d w a t e r
3) B a r l e y l e a f e x t r a c t a g a r :
100 gm o f b a r l e y i n I l i t e r o f d i s t i l l e d
w a t e r w e re p l a c e d i n a n i s o t h e r m a l a u t o c l a v e a t 100° C f o r 30 m in .
To t h e e x t r a c t o f t h i s was ad d e d 20 gm o f B a c t b - a g a r , and 20 gm o f
su cro se.
4) R ic e c e r e a l a g a r :
20 gm G e r b e r ' s r i c e baby c e r e a l
20 gm B a c t o - a g a r
1000 ml D i s t i l l e d w a t e r
5) M o d i f i e d E c k e r t ' s Medium:
1 8 . 0 gm G lu c o s e
3 . 0 gm Y e a s t e x t r a c t
5 . 0 gm P e p t o n e (BBL)
1 . 4 gm K2HPO4
1 . 7 gm KH2PO4
0 . 5 gm M SO,
g 4
2 0 .0
gm B a c t o - a g a r
(BBL)
-97-
M o d i f i e d E c k e r t ' s Medium ( c o n t . ) :
1 0 0 0 .6 ml D i s t i l l e d w a t e r
A l l a g a r t y p e s w e re a u t o c l a v e d a t 121° C f o r 15 m in .
M O N TA N A S T A T E U N IV E R S IT Y L IB R A R IE S
3 1 762 1001 2 9 2 2 8
N378
cop. 2
B j a r k o , M. E.
S o u r c e s o f and g e n e t i c
a c tio n o f re s is ta n c e in
b a rle y ...