Epidemiology of Puccinia hordei and new sources of resistance in barley
by Amor Hassine Yahyaoui
A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in
Plant Pathology
Montana State University
© Copyright by Amor Hassine Yahyaoui (1986)
Abstract:
New virulence types of Puccinia hordei phenotypes were detected in various geographic regions in
Tunisia. Highly virulent isolates able to overcome many sources of resistance were identified. The P.
hordei virulence types reported in this investigation have not been previously identified. They are
important not only because they are virulent on the commonly grown barley cultivars Martin' and
'Ceres', but also because many resistance (Pa) genes are ineffective against these isolates. The
effectiveness of Pag to these virulence types is questionable. Pa3 and Pa7 were very effective against
all P. hordei isolates tested. The naturally occurring Ornithogalum spp. , in Northern and Northwestern
Tunisia, may be a breeding ground for new physiologic races of the P. hordei fungus. Isolates
originating from the alternate host were as variable in virulence as those isolated from barleys in the
same fields.
New genes for resistance to P. hordei appeared to be common in several collections of barley
(Hordeum vulgare L.) land race cultivars originating in Central and Southern Tunisia. Response of five
land race cultivars to a number of different isolates of P. hordei from the Mediterranean region
differentiated them from the known genotypes. A dominant resistance gene that behaved as Pa3 was
found in Tu32. Three of the land race cultivars (Tu17, Tu27, and Tu34) each have a dominant
resistance gene that is different from the previously known resistance genes. The dominant resistance
genes identified in this study were as effective as Pa3 and Pag, and hence, should be considered as new
sources of resistance. Further testing is needed to determine the genetic relationships between these
genes.
EPIDEMIOLOGY OF PUCCINIA HOJDEI
AND NEW SOURCES OF RESISTANCE IN BARLEY
by
Amor Hassine Yahyaoui
A thesis submitted in partial fulfillment
of the requirements for the degree
of
.
Doctor of Philosophy,
in
Plant Pathology
MONTANA STATE UNIVERSITY
Bozeman, Montana
April I986
ii
APPROVAL
of a thesis submitted by
Amor Hassine Yahyaoui
This thesis has been read by each m e m b e r of the
author's graduate c o m m i t t e e and has been found to be
satisfactory regarding c o n t e n t , English usage, f o r m a t ,
citations, bibliographic style, and consistency, and is
ready for submission to the College of Graduate Studies.
____
Date
/
___
Chairperson,
Gradua/e Committee
Approved for the Major Department
Date
Head, Major Department
Approved for the College of Graduate Studies
Date
Graduate Dean
iii
STATEMENT OF PERMISSION TO USE
In presenting this thesis in partial fulfillment
the
of
requirements for a doctorate degree at Montana State
UniversityI
agree
that
the Library
shall
make
available to borrowers under rules of the Library.
quotations from this paper are allowable without
permission,
provided
that
it
Brief
special
accurate acknowledgement
of
source is made.
Permission
reproduction
professor,
when,
the
extensive
quotation
from
this thesis may be granted by my
or in his absence,
in the opinion of either,
material
of
of
for
by the Dean of
or
major
Libraries
the proposed use of the
is for scholarly purposes.
the material in this paper
Any copying or use
for
financial
shall not be allowed without my written permission.
gain
iv
ACKNOWLEDGMENTS
I
wish to express my sincere appreciation and thanks
to Dr. E . L . Sharp, my major advisor, for his interest,
encouragement and guidance during my course work and the
preparation of this thesis.
thanks
\
to a l ong-time
encouragement, his
I want to extend my sincere
f r i e n d , Dr. A. D a a l o u l , for his
unlimited
support
and for serving on
my committee.
Thanks are extended to Drs.
D . Mathre,
Sands,
D.
W . Alexander,
R. Ditterline,
A. S c h a r e n , and
Safford for serving on my graduate committee.
J.
I thank
the faculty, staff and fellow graduate students for their
friendship.
A special acknowledgment to Bob Johnston and
Lee Slater for assistance
with the computer,
to Chuck
Juhnke and Sheila Neilsen for their help, and to Bernie
Sally
and
Drs.
H . Bockelman,
M . Johnston
for
their
assistance and patience.
I wish to thank the entire Mork family, especially
Joyce and Michael Bondurant for making my stay in ‘cold
Montana' enjoyable.
I would like to express my gratitude
to the Tunisian g o v e r n m e n t for supporting my research.
Thanks to Linda Te wait, H. Shabaan,,Sarah Dixon, Drs, W .
Prawl and H. Folks for their a d m i n i s t r a t i v e assistance.
Finally, a special thanks to my dear wife, Colleen, for
her moral support and for typing this manuscript.
V
TABLE OF CONTENTS
Page
A p p r o v a l .....................................
ii
Statement of Permission to O s e ................iii
Acknowledgments..............................
iv
Table of Contents........................ .. .
v
Li s t of T a b l e s ............................. viii
List of Figures..............................
xi
A b s t r a c t .................................... xiii
GENERAL INTRODUCTION ........................
Part I:
I
I
Epidemiology of barley leaf rust
(PucGinia hordei Otth)
in Tunisia
. . . . . . . . . . . .
4
INTRODUCTION .................................
5
II
LITERATURE REVIEH.............................
7
7
Epidemiology Studies ........................
Physiologic Specialization .................
8
Differential Sets............................
9
Life C y c l e .............
10
Detection of New Virulences.................... 11
Control...................................
12
III
MATERIALS AND METHODS........................... 13
Differential Hosts ..........................
13
Leaf Rust C u l t u r e s .......................... 14
Isolate Designation................. ..
I4
I n o c u l u m ............................ ..
16
Inoculation................................... I6
Assessment of Reaction Types ...............
17
Classification and Analysis of the Isolates.
18
IV
RESULTS..........................................
Virulence Patterns of Puccinia hordei
in Northern Tunisia.................
Site I: M a t e u r .............................
Site 2: BouRbia.............................
Virulence Patterns of Puccinia hordei
in Northwestern Tunisia........................
Site I : B e j a ...............................
Site 2: Le K e f .............................
20
21
21
23
23
23
26
vi
TABLE OF CONTENTS - continued
Page
Virulence Patterns of Pucoinia hordei
in Central T u n i s i a ..........................
Site I : K a i r o u a n .........................
Site 2: El J e m ...........................
Virulence Patterns of Puccinia hordei
in Southern Tunisia..........................
Site I: The Oasis.........................
Site 2: M a r e t h ...........
Common Virulence Patterns............... .. .
V
..............................
DISCUSSION .
Virulence Patterns of Puccinia hordei
in Various R e g i o n s .................
Common Virulence Patterns Across Regions . .
Effectiveness,of Resistance Genes to
Puccinia hordei in Tunisia ............. .
Part II:
VI
VII
27
27
28
28
28
30
31
33
33
36
37
New Sources of Resistance to
Puccinia hordei Otth ,in Tunisian
Barley Land Races.................
39
I N T R O D U C T I O N .................................
HO
LITERATURE REVIEH.............................
Importance of Barley in T u n i s i a ...........
Disease P r o b l e m s ............................
Sources of R e s i s t a n c e ....................;■
Inheritance an Resistance genes in barley. .
Effectiveness of the Pa g e n e s .............
41
41
42
43
45
46
VIII
MATERIALS AND METHODS. . ....................
Parent Selection . . . ......................
Inoculum and Inoculation T e c h n i q u e .........
Statistical Analyses . . . . . . . . . . . .
48
48
49
51
IX
R E S U L T S ......................................
P a r e n t s .....................................
Segregation Patterns in
Resistant x Susceptible Crosses...........
Segregation Patterns in
Resistant x Resistant Crosses.............
Segregation in
p B , and Backcross
Generations
. t . . . . . . .
............
52
52
59
60
70
vii
TABLE OF CONTENTS - continued
Page
X
D I S C U S S I O N .................
72
XI
SUMMARY ANDCONCLUSIONS.......................
83
REFERENCES CITED .............................
86
A P P E N D I C E S ...................................
93
viii
LIST OF TABLES
Tables
I.
2.
3.
4.
5;
6.
7.
8.
9.
Page
Collection sites of Tunisian barley leaf
r u s t ,Puccinia
hordei,
isolates
from
I 980-1 9811.......................................
15
Assessment of reaction types of Puocinia
hordei on host d i f f e r e n t i a l s ..................
17
Virulence
patterns of sixteen
Puccinia
hordei
isolates
sampled
at
Mateur,
Northern,
Tunisia, in 1980,
1983, and
1 9 8 4 ............................................
22
Virulence
patterns
of
two
Puccinia
hordei
isolates
sampled
at BouRbia,
Northern, Tunisia, in 19 82 ............... ..
24
.
Virulence
patterns of sixteen
Puccinia
hordei
isolates
sampled
at
Bej a ,
Northwestern, Tunisia, in 1 982 and 1984 . . . .
24
Virulence
patterns
of nine Puccinia
hordei
isolates
sampled
at
Le
Kef,
Northwestern, Tunisia, in 19 82 and 1984 . . . .
26
Virulence
patterns
of
two
Puccinia
hordei
isolates sampled at Kairouan
in
1982,
and one isolate sampled at El Jem
in 1983 , in Central Tunisia....................
28
Virulence patterns of seven Puocinia
hordei
isolates
sampled at the Oasis,
Southern, Tunisia, in I982 ....................
29
Virulence patterns of five
Puccinia
hordei
isolates
sampled
at
Mareth,
Southern, Tunisia, in 1983 ...........
29
ix
LIST OF TABLES
- Continued
Tables
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Page
Common
virulence
patterns of Puocinia
horde!
isolates in Tunisia, in
1982,
1983 , and 1 9 8 4 .................................
32
Prevalent barley
diseases
in Tunisia,
from
1978-1985,
according to observers
with the Montana-AID barley project...........
42
Land race barley cultivars used in this
study and
their site of collection
in
Tunisia.................
49
Reactions of five Tunisian barley
lines'
and
four differential barley genotypes
to nine
Puccinia hordei isolates
from
several locations............... ............. ..
53
Virulence
patterns
of three
Puccinia
hordei
isolates on barley
differential
cultivars. . . . . . . . . .. ..................
53
The
reaction of Fp barley seedlings
to
three isolates of Puccinia hordei (RekaI
x five land races) ; . . ................... ..
.
56
The reaction of Fg barley seedlings
to
three
isolates of
Puccinia
hordei
(Hor25 96 x five land races)
............... ..
57
The
reaction of Fg barley seedlings
to
threeisolates
of
Puccinia
hordei
(Estate x five land r a c e s ) ........... ..
58
The reaction of Fg barley seedlings
to
three
isolates of
Puccinia
hordei
(Cebada Capa x two land races). . ..............
59
Segregation
in F 1 , F3 , and backcross
generations. . .................................
70
X-
LIST OF TABLES
X
- Cbntlnufed
Tables
20.
21.
22.
23.
24.
Page
Initial
studies
of
physiologic
f
s p e c i a l i z a t i o n in the c e r e a l rust
diseases caused by Puccinia s p p .............
94
Description of infection types used in
physiologic specialization studies of
the cereal r u s t s ............................
95
Virulence patterns of Puccinia hordei
isolates sampled in Tunisia in 1982,
1 983,
and 1 9 8 4 ..............................
96
P o s s i b l e g e n o t y p e s i n v o l v e d in the
interaction between (Tu 17 x Cebada Capa)
p r o g e n y and ( T u K e 8 2 - 5 , Tu 0 a 8 2 - I ) P_.
h o r d e i i s o l a t e s ..............................
99
P o s s i b l e g e n o t y p e s i n v o l v e d in the
i n t e r a c t i o n b e t w e e n (T uI 6 x Rekal)
p r o g e n y a n d ( Tu Oa 8 2 -I) Pj. h o r d e i
isolate.........................................
I00
xi
LIST OF FIGURES
Figures
I.
2.
3.
5.
6.
7.
8.
10.
Frequency
distribution
of Fg
barley
seedlings to three isolates of Pi horde!
(Tu 16 x RekaI) .................................
6I
Frequency
distribution
of Fg barley
seedlings to two isolates of £_. horded.
(Tu I7 x RekaI) .................................
6I
Frequency
distribution
of Fg barley
seedlings to two isolates of Pi -hordei
. (Tu27 x RekaI) .................... . . . . . .
2|.
9.
Page
62
Frequency
distribution
of Fg barley
seedlings to two isolates of Pi hordgi
('Tu 31I x RekaI) .......................... ..
62
Frequency
distribution
of Fg barley
seedlings to three isolates of Pi hordei
(Tu I6 x Hor25 96 ) '. ..............................
63
Frequency distribution
of Fg
barley
seedlings to three isolates of Pi hordei
(Tu 17 x Hor25 96 ) ..............................
63
Frequency
distribution
of Fg barley
seedlings to two isolates of Pi hordei
(Tu 34 x Hor2596) ...............................
65
Frequency
distribution
of Fg barley
seedlings to two isolates of Pi hordei
(Tu32 x Hor25 96) ...............................
65
Frequency
distribution
of Fg barley
seedlings to three isolates of Pi hordei
(Tu 16 x Estate ) .............................. ..
66
Frequency distribution
of Fg
barley
seedlings to three isolates of Pi hordei
(Tu 17 x Estate) .................................
66
•xii
LIST
OF FIGURES
- Continued
Figures
Page
.1 1 .
Frequency distribution of F ? barley
seedlings to two isolates of P . horde!
(T u 2 7 x E s t a t e ) ........
I2 .
Frequency distribution of F p barley
seedlings to two isolates of P . hordei
(Tu 3 2 x Estate)
. . . _
13 .
Frequency distribution of F p barley
seedlings to three isolates of Pi horde!
(Tul 6 x Cebada Cana) . . . .
11J.
Frequency distribution of F p barley
seedlings to three isolates of Pi hordei
(Tul? x Cebada Capa) ..........
I5
Map of Tunisia
101
xiii
ABSTRACT
New
virulence types of Puccinia horded. phenotypes
were
detected in various geographic regions in
Tunisia.
Highly virulent isolates able to overcome many sources of
resistance
were
identified.
The Pj. horde!
virulence
types
reported
in this
investigation have
not been
previously
identified.
They
are important
not only
because
they are virulent on t h e .commonly grown
barley
cultivars
*Martin 1 and ’Ceres1, but also because many
resistance
(Pa)
genes are
ineffective
against
these
isolates.
'The effectiveness of Pag to these
virulence
types is questionable.,
Pa, and Pay were very
effective
against
all Pjl horded isolates tested.
The naturally
occurring Ornithogalum spp. , in Northern and Northwestern
Tunisia, may
be a breeding ground for new
physiologic
races of the Pel. horded, fungus. Isolates originating from
the alternate host were as variable in virulence as those
isolated from barleys in the same fields.
New genes for resistance to Pi horde! appeared to be
common in several collections of barley (Hordeum yulgare
L .) land
race
cultivars
originating
in Central and
Southern Tunisia. Response of five land race cultivars to
a number
of different, isolates of Pi horded. from the
Mediterranean region differentiated them from the known
genotypes.
A dominant resistance gene that behaved as
Pag was found in Tu32.
Three of the land race cultivars
(Tu I7 » Tu 27 , and
TuS 1I) each have a dominant resistance
gene
that
is different
from
the previously
known
resistance
genes.
The dominant
resistance
genes
identified
in this study were as effective as
Pag and
Pag,
and hence, should be considered as new sources of
resistance.
Further testing is needed to determine
the
genetic relationships between these genes.
I
GENERAL INTRODUCTION
Barley
important
(Hordeum
vulgare
L.)
cereal crops in Tunisia.
thirty percent
one
of
the
most
It occupies about
of the total cereal production area which
is over half a million hectares.
crop,
is
Barley is mainly a food
generally g r o w n in southern and central Tunisia,
where climatic conditions are less favorable for growing
wheat.
In
the
northern
region,
barley
is
marginal areas or as an alternative crop in
Recently,
farmers
in
this
region
have
grown
rotation.
become
interested in using barley for forage and feed,
some instances for malting.
in
mor e
and in
Malting barley can become an
important crop in this region due to its high cash value
and its potential as an export crop.
major interest in increasing
northwestern,
central
In recent years a
cereal production in the
and southern regions
with a major
emphasis on barley, has become a priority in agricultural
development programs in Tunisia.
As interest in barley increases,
and consequently
the acreage, the lack of resistance to diseases such as
leaf rust, will become the most limiting factor in barley
2
production.
Yield losses could be especially high in the
northern region where the climatic conditions are more
favorable for pathogen development.
Leaf
r u s t , caused
by
the
fungus
Puccinia
horde!
O t t h , has increased in intensity on the currently grown
barley cultivars.
a
significant
because
there
growers.
factor
in
limiting
were no large
scale
barley
epidemics
to be
production
observed
by
Nevertheless., the severity of this disease is
becoming
obvious
agronomists
develop
This disease was not considered
to
breeders,
in Tunisia.
pathologists
and
Thus there is an urgent need to
resistant cultivars.
It is very important
then,
to detect the changes in pathogenicities of the fungus so
that
breeders
resistant
will
be
able
to
develop
and
maintain
cultivars.
Presently,
nine
major genes conditioning
resistance
to leaf rust have been identified and are designated as
the Pa through Pag.
Barley leaf rust, as well as other
barley diseases have received very little attention in
Tunisia.
resistant
initiated:
To develop
barley
high yielding,
lines,
the
adapted
following
leaf rust
studies
were
3
Part
I.
Epidemiology
of barley leaf rust
(Puccinia hordei
Part II.
Ot t h ) in Tunisia.
New sources of resistance to
Puccinia hordei Otth in Tunisian barley
land races.
PART I
EPIDEMIOLOGY OF BARLEY LEAF RUST
(PUCCINIA HORDEI OTTH) IN TUNISIA
5
PART I
I.
Disease
INTRODUCTION
surveys
are
an
important
tool
for
plant
breeders, and provide useful information pertinent on the
distribution
populations
of pathogenic
entities
of the pathogens.
and
Virulence
on. shifts
in
in leaf rust of
b a r l e y , caused by Puccinia horde! O t t h , its i m p o r t a n c e ,
and the variability
in many
in host resistance are being studied
parts of the world.
Very l i t t l e , however,
is
known about the importance of this disease in Tunisia,
except for the
which
work
done
characterized
in
1982 (Reinhold
the. r e l a t i v e
and
Sha r p )
effectiveness
of
resistance genes against one Tunisian leaf rust isolate.
Leaf rust disease of barley, as well as other barley
diseases have
Recently
there
practices used
the
received very little attention in Tunisia.
has
to grow
e p idemiology
rust.
been
of
marked
barley
changes
which may
many, diseases,
T h e r e f o r e , the objectives
this thesis revolve around
in
cultural
directly
effect
particularly
leaf
of the first part
of
a study of the epidemiology
6
of barley leaf rust in Tunisia and are as follows:
1.
To determine the virulence pool of leaf rust in
various barley growing areas of Tunisia.
2.
To dete r m i n e the changes in virulence within
each
region
and
within
the
country
over
a
period of two to three years.
3.
To
determine
ineffectiveness
the
of
effectiveness,
known
against Tunisian Pi hordei
resistance
isolates.
or
g e n e (s )
7
II.
LITERATURE REVIEW
EfiidemioIOgjr Studies
Race
surveys
provide
valuable, i n formation
on the
distribution and frequency of various rust physiologic
races in different geographic
has
not
renewed
been
effectively
interest
may
regions.
exploited
enhance
Such information
by
breeders,
its use.
but
Chester (1946)
showed that certain races of wheat leaf rust were present
in the same area year after year.
According to Roelfs
(1974), such a pattern still exists but the reasons are
unclear.
Virulence of barley leaf rust, its importance, and
host resistance
authors.
The
variability have been studied by many
appearance
geographic
area could
following:
(I)
an
of
result
input
of
a new
from
race
one
exogenous
in
or
a certain
more
inoculum
of the
(L u i g ,
1977), (2 ) a mutation for virulence or avirulence in an
existing
race
(Stakman
et
al. , 1 9 3 0 ),
(3 ) asexual
or
parasexual r e c o m b i n a t i o n (Newton et al. , 1930) , or (4)
detection
threshold
alternate
of
a
race
previously
(Roelfs et al.,
host(s)
and
must not be ignored.
1982).
wild grasses
below
Also,
the
detection
the effects
that could
of
be host(s)
D'Oliveira (I960) showed that among
/
8
the Ornith o g a l u m
only
Oa
species in the Medite r r a n e a n region,
a r a hi C u m
Critopoulos
was
incompatible
(1 9 5 6 ) demonstrated
the
with
the
significance
rust.
of
the
alternate host in the perennation of Pa horde! in Greece.
Studies
by
Anikster
Ornithogalum
sp p A
(I9 8 2 ) showed
play
an
that
important
indigenous
ro l e
c o m p l e t i o n of the life cycle of Pa hordei.
in
the
Wahl (1984)
reported that Pa hordei can also attack various grasses
of the
Hordeum
SEontaneuQ .
hordei
from
different
genus;
Ha bulbosum , Ha m u r i m u m , and Ha
It is not clear,
these
however,
whether or not JLt
Hordeum Sp e a should be classified as a
formae
specialis,
as
suggested
by
Anikster
(1984).
Physiologic Specialization
The occurrence
first
demons t r a t e d
of physiologic races in Puccinia was
by
Stakman
in
the
early
1920*s,
a
decade which he referred to as ^the decade of the race"
(Stakman, 1929).
The earliest reports of races in cereal
rusts are shown in Appendix Table 20.
The
virulence
specialized
of
pathogens,
isolates
such
simple nor easy to describe.
parasite systems accumulate,
as
of
the
physiologically
rusts,
is neither
As data relating to hostand as new differentials are
9
discovered and used, the description becomes increasingly
complex
and
difficult
complexity
has
been
to
interpret.
reviewed
by
This
Browder
aspect
(1971)
of
and
Browder et al. (1980).
The
(1965)
pathogenicity
seems
to be
virulence studies.
described
by
a
formula
a good
method
way
to
proposed
present
by
Green
results
of
In this method physiologic races were
"virulence
"effective/ineffective
formula"
host.genes".
of
the
This
for m
method
has
since been adapted
to describe pathogenicity
in Pi strii f o r m i s
(Volin and S h a r p , 1 97 3), Pi g ram in is
avenge (Marten et al.,
and Browder,
differences
197 9), and Pi recondite
(Loegering
1971).
Differential Sets
Differential
physiologic
host
sets
are
used
specializaion of rust fungi.
of a selected
group
of genotypes,
specific gene or gene c o m b i n a t i o n
specific
rust
genotypes
are characterized
resistance
entity.
gene
In
Pa,
combinations
different
barley
genotypes,
of
A set consists
for resistance
of
after
to a
barley
by a USDA Cl n u m b e r
scientific name, Puccinia anomala.
gene
studies
each of which has a
the. case
designated
g e n e (s ) or
in
the
the
and a
former
Nine resistance Pa
have
been
and
are
I
identified
use d
as
in
host
10
differentials of Pj. hordei.
The resistant
Pa genes
in
various barley cultivars have been described and reviewed
by many authors
(Clifford, 197 4,
1977;
Parlevliet, 1976;
Tan, 1977).
Infection Typ.es
Infection
type,
as a m e a s u r e m e n t
of disease,
adapted by Stakman and c o-workers at Minnesota
early
1920's.
was
in the
This system is described in Appendix Table
21 and has been adapted
to most cereal rusts.
Life Cycle
The pathogen Pi hordei is an obligate parasite with
a highly complex life cycle.
Two spore forms develop on
Eond e u m SjDp^ and three additional forms develop on the
alternate host.
the
most
Of these spore forms, urediospores are
important
because
they
enable
repeated
cycles,
spread of the disease from field to field, and survive
from
year
to
year.
In
temperate
Europe,
Pjl hordei,
overwinters in winter barley rather than on its alternate
host (Tan, I 976 ).
Thus the alternate host Ornithpgalum
Sppji. appears to be u n important in the perennation of
hordei in this region.
Tan (1976) showed that the fungus
survives the winter in the form of dormant urediomycelium
on the primary host.
In parts of the Mediterranean,
the
fungus is known to cycle between the main host Hordeum
and
the
I 9 8 2).
also
alternate
host
Ornithogalum
sjofij. (Aniks t e r ,
D'Oliveira (I 960), reported that the fungus can
cycle
between
Hordeum
and
Dipcadi
erythraeum
Webb,
et Bert, or Hordeum and Leopoldia eburnea Eig. et Feinbr.
Anikster (.1 982) proved
that
these plant species are also
potential alternate hosts of Pi hprdei.
Wahl
et
a I . (1984)
showed
that
the
sexual
stage
contributes to the diversification of the spectrum
parasitism
population
of
Pi
from
hprd e i .
He
the alternate
found
host
that
showed
new
the
of
rust
virulence
patterns on barley genotypes.
Detection of New Virulenpes
A major goal
of any
virulence phenotypes.
each
race
survey
By using host
is to detect new
differential
with a "single gene" for resistance,
lines,
it is possible
to detect changes in virulence, and then to determine if
that results in changes in a virulence c o m b i n a t i o n that
is capable of overcoming the combination of resistance in
commercially
grown
cultivars
material.
Rust
cultures
ineffective
all known genes
including Pag, Pay,
from
or
advanced
breeding
Ornithpgalugi
rendered
for resistance to leaf rust,
and Pag (Golan et al., 1978).
Barley
leaf
rust
isolates
virulent
on
Pay
have
been
reported
by
P a r l e v l i e t et a I . (1981).
Control
Biological
'
control
through
plant
breeding
has
been
the principal method used to control the cereal rusts.
This method has been highly effective against barley leaf
rust.
Fungicides
applied
as
foliar
sprays
can
be
used
effectively to protect the cereal crop, but are usually
uneconomical.
13
III.
MATERIALS AND METHODS
Differential Hosts
Thirteen
different
spring
barley
Pa genes, were
genotypes,
subjected
possessing
to detailed
analyses
of their reactions to Tunisian cultures of Pj. hordei.
Pa designation by Clifford (1974,
The
1977) and the USDA Cl
number are given in parenthesis following the common name
of each genotype used.
The differentials used include
the following barley cultivars:
2)
Cebada
1243),
(Pay,
Capa
Cl
4) Ricardo (Pag+,
I) Estate (Pag, Cl 3410),
6 193),
3)
Cl 6306),
Hor
(Pag,
2596
Cl
5) Bolivia (Pa 2 + Pa6 ,
Cl 1257), 6 ) Quinn (Pa 2 + P a 5 , Cl 1024), 7) Magnif (Pa5 , Cl
8)
1 3 806 ),
6489),
10)
Peruvian
Egypt
(Pa2 , Cl
(Pag,
Cl
9 3 5),
6481),
9)
11)
Sudan
Batna
(Pa,
Cl
(Pa2+,
Cl
33 9 1 ), 1 2) Gold (Pa1,, Cl 1145), and 13) Reka I (Pa2+, Cl
5051).
will
Throughout this study
be
listed
in
the
same
the differential
order
so
that
cultivars
the
arable
number given to each can be used.in the virulence formula
method
(Green,
a r r a n g e d , as
spectrum
I 96 5 ).
much
as
of resistance.
The
differentials
possible,
The
begins each table in the thesis.
most
according
are
to
also
the i r
resistant genotype
Leaf
Rust Cultures
Samples
different
of P_. h o r d e I w e r e
geographic
representative
sites
regions
were
collected
in
chosen
from
Tunisia.
in
ea c h
four
Two
region.
Collections were made over a period of three years (19821984).
Samples were taken at the same site every year
when feasible.
collection,
Table I shows the region, site, year of
and the number of monouredial isolates tested
from each collection site.
The sites and
regions are
also shown in Appendix Figure 15.
Isolate Designation
The designation given for the isolates include the
country, site and year of collection and isolate number
within
each
site.
shown in Appendix
A complete
Table 22.
list of the isolates is
Throughout
the
study
the
isolates are listed in an ascending order of v i r u l e n c e ,
ie. the least virulent isolate will be listed first and
the most virulent last.
Table I.
Region
North
Northw e st
Central
South
1
Collection sites of Tunisian barley leaf rust,
Puccinia horde!, isolates from 1980-1984.
Leaf Rust Collection
Year
Site
No. of Monouredial
Isolate(
I1
Mateur (Ma)
Mateur (Ma)
Mateur (Ma)
BouRbia (Br)
I980
I983
1984
I982
Beja (Bj)
Beja (Bj)
Le Kef (Ke)
Le Kef (Ke)
I982
I 984
1982
11
82
10
I984
3
KairaoUan (Kr)
El Jem (Ej)
1982
2
1983
I
1982
8
2
10
Oasis (Oa)
Oasis (Oa)
Mareth (Mr)
I984
1983
16
6
2
Isolate collected by Dr. E. L. Sharp (Reinhold and
Sharp , I 982).
2 Fiv e of the e i g h t i s o l a t e s w e r e c o l l e c t e d fro m
Ornithogalum.
16
Inoculum
Rust spores from a single uredium were isolated from
green or dried leaves collected in Tunisia.
In one case
m o nouredial cultures were derived from a single aecium
from
the
alternate
hos t
Monou r e d i a l cultures
at
the
Beja
(Bj)
location.
were multiplied on the universal
susceptible barley cultivar, Moore (Cl 7251).
Inoculum
that could not be used within a few days was vacuum dried
and
stored
technique
The
United
at
4 C , until
further
use,
according
to
a
described by Sharp (1957).
Pj. horde!
isolates
States according
regulations
environmental
and
were
introduced
into
the
to U.S.D.A. q u a r r a n t ine permit
were
tested
under
controlled
of
of the
differential
conditions.
Inoculation
Three
to
five
seeds
each
cultivars were sown in 10 cm diameter plastic pots in
sterilized
Bozeman
silt
loam
soil.
Initial
single
uredium inoculation of the universal susceptible was done
by gently
rubbing
spores
drop of distilled water,
index
that had been suspended in a
on the leaf using the thumb and
finger.
Prior to inoculation, the spores were hydrated for
four hours in 100 percent
relative
humidity.
Sin g l e ­
17
leaf-stage barley seedling differentials were misted with
distilled water,
then dusted with rust spores that had
been mixed with talc (I mg spores/ 5 mg talc) using a small
hand powder duster.
from
the
cultivar
Urediospores
Moore
which
following each inoculatioh.
were collected only
was
kept
in
isolation
Inoculated seedlings were
kept for 20 to 24 hours in a dew chamber maintained at
20+1 C and in 100 percent relative humidity.
They were
then placed in controlled environment chambers maintained
at
2 0/15
C
and
a
I6 / 8 h r
photoperiod
(2.2-3.3
x
I0 ^erg/cm 2 sec) day/night regime.
Assessment of Reaction Types
Readings of developed pustules were made
days after.inoculation.
reaction
Table .2.
Six infection classes and three
types were recorded (Table 2).
Assessment of reaction types of Puccinia horde!
on host differentials.
Infection Reaction
Class
Type
0
0;
R
R
I
R
2
I
S
S
3
4
10 to 12
Symptom
Description
no visible rust pustules
no visible rust pustules, but
necrosis is present
some pustules, small, chlorosis
and/or necrosis present
moderate size pustules with chlorosis
large pustules with some chlorosis
large pustules and no chlorosis
All readings of symptoms and signs were made on
first
leaf of each genotype.
distinct,
one
proved
test was considered sufficient.
distinct cases,
between
When the reaction
the test was repeated.
the
In less
The interaction
the 13 barley differentials and 78
monouredial
Tunisian rust isolates was determined.
Classification and Analyses of the Isolates
In
the interest of simplicity the rust reaction
each genotype is summarized by a single letter "R",
or n S n instead of the conventional system.
a
computer
comparing
analysis
program, was used for
only
the
resistant (R)
sorting
In the
and
"I",
In this study
ranking,
the different isolates.
of
and
computerized
susceptible
(S)
reactions were used for ranking the isolates and checking
for duplicates among isolates.
the
intermediate
In the virulence formula
(I) and resistant (R)
both considered as resistant (R).
with
only
those
with
considered ineffective.
isolate,
reaction
separately
type
the
an
S
reaction
effective,
type
were
In. each table, and for each leaf
the
total number of genotypes
(R ,
I,
number
were
Differential genotypes
an R or I reaction type were considered
whereas
rust
reactions
or S )
of
is
listed.
genotypes
in
for
By
the
each
listing
R
or
I
19.
category,
relative
the
reader
is
more
effectiveness
or
able
to
visualize
ineffectiveness
the
of
the
respective Pa resistance gene(s), or gene combinations.
The large array of data and the compl e x i t y of the
analysis
prompted
the need
Computer
manipu l a t i o n
of
for
the
computer
data
scheme based on Flor's gene-for-gene
1971).
This
program
is
capable
application.
involved
theory
of
a sorting
(Flor, 1946,
sorting
and
classifying a large number of isolates in an increasing
order
of
virulence.
It also
duplicate isolates separately.
evaluation
of
ineffectiveness"
the
of
sorts
and
lists
any
Computations allowing the
relative
resistance
combinations are also performed.
out
"effectiveness /
genes
and
gene
20
IV.
RESULTS
A total of 7 8 single uredium isolates of
were
analyzed
patterns
of
collection
(Appendix
the
P_.
(Table
Table
22).
horde! isolates at
The
virulence
each
I) are shown in Tables 3
Duplicate isolates were omitted,
Pj. horded,
site
of
through
9.
and the ranking of
the
isolates was based on the R/S reaction types.
Virulence Patterns of Puccinia horde! in Northern Tunisia
Site lx
Mateur IMal
Leaf rust isolate TuMaSO
this
(Table 3) was collected at
in 1 9 80 and was previously studied
site
and Sharp, I9.82) .
(Reinhold
The virulence formula for this isolate
i.,
I.
TuMaSO-I:
I ,2,3,4,5,6,8,9/7,10,11 ,12,13
In 19 83, thirteen additional Pj. horde! isolates were
identified.
3.
The
Their virulence patterns are shown in Table
1983 Mateur isolates were characterized by
following virulence formulae:
1.
TuMa83-15:
1,2,3,4,6,7,8,11/5,9,10,12,13
2.
TuMa83-2:
I ,2,3,4,6,8,9,11/5,7,10,12,13
3.
TuMa83-14:
I ,2,3,4,5,6,7,9/8,10,11 ,12,13
4.
TuMa83-l6:
I ,2,3,4,6,7,9/5,8,10,11,12,13
the
21
5.
TuMa83-3:
I ,2,3,4,5,9,11/6,7,8,10,12,13
6.
TuMa83-5:
1,2,3,4,5,9/6,7,8,10,11,12,13
7.
TuMa83-12:
I ,2,6,7,9/3,4,5,8,10,11 ,12,13
8.
TuMa83-11:
1,2,3,4,6/5,7,8,9,10,11,12,13
9.
TuMa 83- 6 :
I ,2,12/3,4,5,6,7,8,9,10,11 ,13
10.
TuMa83-1:
1,2,4/3,5,6,7,8,9,10,11,12,13
11.
TuMa83-7:
I ,2,3/4,5,6,7,8,9,10,11,12,13
12.
TuMa83-4:
I ,2,9/3,4,5,6,7,8,10,11 ,12,13
13.
TuMa83-8:
I ,2/3,4,5,6,7,8,9,10,11 ,12,13
22
Table 3.
Virulence patterns of sixteen Puccinia hordei
isolates sampled at M a t e u r , Northern Tunisia
in I 980 , 1 983 and 19 84.
Differential Host Genotypes
I 2 3 4
5
6
8
7
10
9
11
12 13 Resis^
Isolate Esta C.Ca Hor Rica Bolivia CKiinn Mign Peru Suda %yp Batn Gold Reka Genes
RBg Eciy Pag
Rag+Rag Ra^+Ra^ Pa^ Ifa2 ..Ra Fb8 Ifa2+ Ra*) Efa2+ R I S
TUMa 80-1 R
R
R
I
I
I
S
TUMa 83-15 R R
TUMa 83-14 R R
TuMb 83-2 R R
TUMa 83-16 R R
TUMa 83-12 R R
TUMa 83-11 R R
TUMa 83-5 R R
Mfa 83-3 R R
Mfa 83-6 R R
Mfa 83-1 R R
Mfa 83-7 R R
Mfa 83-4 R R
Mfa 83-8 R R
R
I
R
I
S
R
II
S
S
I
S
S
R
I
R
I
S
R
I
I
S
R
S
S
S/
S
R
S
S■
S
S
I
R
S
S
S
S
S
R
R
I
R
R
I
S
S
S
S
S
S
S
R
R
S
R
R
S
S
S
S
S
S
'S
S
Mfa 84-5 R
Mfa 84-3 R
Mfa 84-1 R
R
R
S
R
S
R
S
S
S
S
S
S
S
S
S
I
R
R
R
I
R
S
S
S
S
I
S
S
R
I
R
S
R
S
R
S
S
S
I
S
I
S ■ S
S
S
S
S
S
I
S
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
S
S
S
S
S
R
S
S
S
S
S 6 25
S 6 25
S 535
S 526
S 508
S .4 I8
R 3 46
S 3 46
I 3 I9
S 3 0 10
S 2 I 10
S 2 I 10
S 2 0 11
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
445
409
3 0 10
3 0 10
Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
23
Table
3 also
shows
hordei
isolates
Mateur
in
isolates
the
virulence
identified
1984.
Only
identified
one
in
pattern
from
of
three
collections
made
isolate
I 983
at
differed
this
same
Pjt
at
from
the
site.
Its
virulence formula is as follows:
1.
The
TuMaS 4-5:
other
two
virulence
I ,2,3,4/5, 6 ,7 ,8 ,9 ,1 0 ,11,/I2,13
isolates,
formulae
that matched
TuMa83-1
respectively.
Site 2i
BouRbia lfirl
Table
different
Igg2 .
4
Pa
The
TuMa84-8
shows
hordei
the
and
those of TuMa83-7 and
virulence
isolates
virulence
Tu Ma 84 - 1 , have
patterns
collected
formulae
at
of
two
BouRbia
showing
in
the
•'effectiveness/ineffectiveness” of host sources for these
two isolates are as follows:
I.. TuBr82-1:
2.
TuBr 8 2-2:
I ,2,3,4,5,6/7,8,9,10,11,12,13
1 ,2 ,3 ,4 ,5 ,7 / 6 ,8 ,9 ,1 0 ,1 1 ,1 2 , 1 3
Virulence Patterns of Pucciriia hordei
Northwestern Tunisia
Site Ii
The
in
fieja Ifijl
virulence
patterns
of
the
sixteen
leaf
isolates identified at this site in 1982 and in
shown in Table 5.
rust
I9 84 are
The nine isolates identified.in 1982
Table 4.
Virulence patterns of two Puccinia hordei
isolates sampled at BouRbia> Northern Tunisia,
in 1982.
_______ rHfffermhial Host Genotypes,_____ :
---------.
1
2 3 4
5
6
7
8
9
10
11 12
13 Besis
Isolate Esta C.Ca Hor RLoa Bolivia Quinn Magn Peru Suda Efeyp Batn Gold Reka Genes
Ba3 Ra7 Bag Ba2+ Ba2^Ba6 Pa2+Pa5 Ba5 Ba2 Eti I^8 Ba2+ Ba1, Eti2+ B I S
TuBr 82-1 R
IUBr 82-2 R
R
R
R
R
R R R I
I
S
• S
S
S
I S S
S
S
S
S 5 17
S S S S 4 2 7 S
*
I Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
Table 5 .
Virulence patterns of sixteen Buccinia hgrdei
isolates sampled at Beja,Northern Tunisia,
in I 982 and I 984.
Piffprsntial Host Genotypes________ _______
.
! 2 3 H
5
6
7
8
9 10 11
12 13
Basis'
Isolate Esta C.Ca Hor Rica Bolivia Quinn Itign Peru Sada Efeyp Batn Gold Reka Genes
Eti3 Eti7 Bag Eti2+ Ba2TtEtig Eti2H-Eti5 Ba5
Eti2 EtiBag
Ba2+Ba1,Ba2+B I S
TUBj 82-9 R
TUBj 82-1OR
IUBj 82-2 R
TUBj 82-1 R
TUBj 82-7 R
TUBj 82-4 R
TUBj 82-11R
TUBj 82-8 R
TUBj 82-6 R
R
R
R
R
R
R
R
R
R
R
R
R
R
I
R
S
I
S
R
R
R
R
I
R
R
S
S
R
R
S
R
S
S
S
S
S
S
I
S
S
R
S
S
I
S
S
R
S
S
I
S
S
S
S
I
S
I
I
S
S
S
S
S
R
S
S
S
R
S
S■ S
S
R
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S 6 I6
S 6 I6
S 5 I7
S 5 I7
S 436
S 40 9
S 3 0 10
S 22 9
S 2 0 11
TUBj 84-1 R
TUBj 84-2 R
TUBj 84-8 R
TUBj 84-4 R
TUBj 84-7 R
TUBj 84-3 R
TUBj 84-5 R
R
R
R
R
R
R
R
S
R
I
R
S
I
S
R
R
S
R
R .S
S
I
S
R
S
R
S
S
S
I
S
S
S
I
S
S
S
S
S
S
S
S
R
S
R
S
S
S
S
R
S
S
S
S
S
S
S
S
S
S
I
S
S
S
R
R
I
I
S
S
S
S
S
S
S
S
S
S 607
S 5 I7
S 5 I7
S 32 8
S 328
S 328
S 2 0 Tl
I
Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
25
were
categorized
based
on
the
relative
"effectiveness / i n e f f e c t i v e n e s s " of the barley genotype
resistance
genes
and
gen e
combinations
and
were
differentiated as follows:
I.
TuBJ82-10:
1,2,3,4,5,6,7/8,9,10,11 ,12,13
2.
TuBJ82-9:
1 ,2 .,3,4,5,8,10/6,7, 9,11 ,12,13
3•
TuBJ82-7:
I ,2,3,4,6,7,9/5,8,10,11,12,13
4.
TuBJ82-2:
I ,2,3,4,8,10/5,6,7,9,11 ,12,13
5.
TuBj82-1:
I ,2,3,4,5,8/6,7,9,10,11,12,13
6.
TuBJ82-4:
I ,2,3,4/5,6,7,8,9,10,11 ,12,13
7.
TuB j82-8:
1,2,3,6/4,5,7,8,9,10,11,12,13
8.
TuBj 82-1 I :
I ,2,4/3,5,6,7,8,9,10,11 ,12,13
9.
TuBJ82-6 :
I ,2/3,4,5,6,7,8,9,10,11 ,12,13
In
identified
1984,
from
seven
Pj. h o r d e !
collections
made
at
isolates
this
site.
The
virulence patterns of these isolates are shown in Table
5.
Four of the monouredial cultures were isolated from
single aecia from the alternate host (Ornithogalum Sfifij.).
The virulence formulae of these isolates are:
I.
TuBj84-8:
I ,2,3,4,8,11/5,6,7,9,10,12,13
2.
TuBj84-4 :
1,2,3,4,11/5,6,7,8,9,10,12,13
3.
TuBJ84-7 :
I ,2,4,10,11/3,5,6,7,8,9,12,13
4.
TuBJ84-5:
1,2/3,4,5,6,7,8,9,10,11,12,13
three isolates that were collected from the
26
cultivar g ro w n in the same field as the alternate host
have the following virulence formulae:
1.
TuBj84-2:
1,2,3,4,6,11/5,7,8,9,10,12,13
2.
TuBj84-I :
I ,2,4,5,8,9/3,6,7,10,11 ,12,13
3.
TuB j 84-3:
I ,2 ,3 ,4 ,6 / 5 ,7 ,8 ,9 ,1 0 , 1 1 ,12,13
Site 2j. Le Kef IKel .
At
this
site,
nine
Jiordei
isolates
wer e
identified in 1982 and two isolates in 1984 (Table 6 ).
Table 6. Virulence patterns of nine Puccinia horde!
i s o l a t e s s a m p l e d at Le Kef, N o r t h w e s t e r n ,
Tunisia, in 1982 and 1984.
Differential Host Genotypes
1 2 3 4
5
6
7
8
9
10 11 12 13 Resis
Isolate Esta C.Ca Hor RLca Bolivia Quinn Pbgn Peru Suda Ejgyp Batn Gold Iteka Genes
Pa3 Pay Pag Pa2+ Pa^Pag Pag+Fbg Pag Pa2 Pa Ite8 Pa2+ Pa% Ea2+ R I S
R
I
S
S
S
S
S
S
S .
S
R
R
S
S
S
S
S
S
S
S
S
S
S
M e 82-5 R
TuKe 82-4 R
IUKe 82-6 R
M e 82-3 R
M e 82-8 R
M e 82-10R
M e 82-9 R
R
R •R
R
R
R
R
R
R
R
R
R
S
R' R
I
I
R
S
S
R
R
R
R
S
M e 84-2 R
M e 84-3 R
R
R
I
S
R
S
S
S
S
S
S
S
S
S
R
R
S
S
S
S
S
R
R
S
S
S
S
S
S
S
S
S
S
S
I
I
S
S
S
S
S
S
S 904
S 8 23
S
S
S
5 I7
40 9
S
S
S
S
S
S
2 0 11
S
S
S
S
S
S
2 0 11
3 0 10
S 229
3 I9
1 Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
27
The virulence formulae of the 1982 isolates are:
I.
TuKe82-4:
I ,2,3,4,5,6,7,8,9,11/10,12,13
2.
TuKe82-5:
1,2,3,4,5,6,7,9,11/8,10,12,13
3•
TuKe82-6:
1,2,3,4,5,8/6,7,9,10,11,12,13
4.
TuKe 82-3:
I ,2,3,4/5,6,7,8,9,10,11,12,13
5.
TuKe82-I0:
1,2,3,4/5,6,7,8,9,10,11,12,13
6.
TuKe82-8:
I ,2,3/4,5,6,7,8,9,10,11 ,12,13
7.
TuKe 82-9:
I ,2/3,4,5,6,7,8,9,10,11 ,12,13
The virulence patterns of the 1984 isolates were similar
if not identical to some isolates that were identified
the
previous
formula
Tu Ke 8 4 -1
year.
as TuKe82-9 and
cultivar
Ricardo
the
same
virulence
TuKe84-2 differed very slightly
from the TuKe82-8 isolate.
the
has
The main difference was on
(Pag+,
Cl
6306)
which
showed
a
susceptible reaction type to the 1982 isolate T u K e 8 2 - 8 ,
but an i n t e r m e d i a t e
reaction type to the 1 9 8 4
isolate
TuKe84-2.
Virulence Patterns of Puccinia horde! in Central Tunisia
Site I jl
Kairouan IKrl
Only one leaf rust isolate
was identified from
rust collections made at Kairouan.
isolate
is
shown
in
Table
7.
The virulence of this
The
virulence
associated with this isolate is:
I.
TuKr82-I:
19 82
I ,2,3,4/5,6,7,8,9,10,11 ,12,13
formula
28
Site
El Jem U j l
Table 7 shows the virulence pattern of the isolate
identified from the 1983 rust collection made at El Jem.
The virulence formula that fits this isolate is:
I.
TuEj 83 - I:
1,2,3,4,5,6,7/8,9,10,11,12,13
Table 7. Virulence patterns of two Puccinia horde i
isolates sampled at Kairouan in 1982, and one
isolate sampled at El Jem in 1983, in Central
Tunisia.
Differential Host Genotypes
.:___________
.
5
6
7
8
9
10 11 12 13 Resis1
Isolate Esta C.Ca Hor Rica Bolivia Quinn Magn Peru Suda Efeyp Batn Gold Reka Genes
Ba3 Ra7 Pa9 Ra2+ Rag+Pag Ba2^Ba5 Ra5 Ba2 Ra Pag Ra2+ Ba*, Ra2+ R I S
___________
1 2
3 4
Kairouan
ThKr 82-2 R
TUKr 82-1 R
R R R S
R
I
R
S
S
S
ElJan
ThEj 83-1 R
R
R*
S
1
R
R
R
S S
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S
S
S
409
3 19
6 I6
Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
Virulence Patterns of Puccinia horde! in Southern Tunisia
Site U
The Oasis ifial
Seven highly variable leaf rust isolates were sorted
out from
1982.
leaf rust
samples
8
the
Table
isolates.
shows
collected
virulence
in
the
patterns
Oasis
of
in
these
29
8.
Table
Virulence
patterns
of . seven Puccirjia
horde!
isolates
sampled
inthe Oasis,
Southern Tunisia, in 1982.
_________ TMffterantial Host Genotypes
----------.
----2 3 4
5
6
7
8
9
10 11
12 13 Kesis
Isolate Esta C.Ca Hor Rica Bolivia Quinn Magn Peru Suda Egyp Batn Gold Reka Genes
Ry Pa?
PagPag+ PagtPa6 PagtPa5
Pa5
Pa2
Pa
Pa8
Pa2+Ra4 Pag+R I S
HiQa 82-6 R
TuOa 82-4 R
TuCa 82-3 R
TUQa 82-8 R
HiOa 82-7 R
TUOa 82-5 R
TUOa 82-1 R
R
R
R
R
R
R
R
R
R
I
I
S
R
S
R
S
I
R
I
S
S
R
S
I
I
S
S
S
S
I
S
S
S
S
S
S
I
R
I
R
S
S
S
R
S
S
I
S
S
R
S
S
S
S
S
S
S
S
I
S
I
S
S
R
I
R
I
S
S
S
S
S 706
S 4 45
S 445
S S
346
S
S 337
S
S 3 0 10
S
S 2 0 11
I
S
I Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
The
known
resistance
differentials
used
genes
when
in
tested
"effectiveness/ineffectiveness"
the
barley
for
their
against
the
Oasis
isolates behaved as follows:
I.
Tu0a82-6:
1,2,3,4,5,10,11/6,7,8,9,12,13
2.
TuOa82-4:
I ,2 ,3 ,6 ,7 ,8 , 1 1 ,1.2/4,5,9,10,13
3.
TuOa82-3:
1,2,3,4,5,6,9,11/7,8,10,12,13
4.
Tu0a82-8:
I ,2,3,4,5,6,11/7,8,9,10,12,13
5.
Tu0a82-7:
1,2,4,6,8,9/3,5,7,10,11 ,12,13
6.
Tu0a82-5:
I ,2,3/4,5,6,7,'8,9,10,11 ,12,13
7.
Tu0a82-I:
I,2/3,4,5,6,7,8,9,10,11 ,12,13
In 1984,
only two virulence
Oasis.
Their
virulence
type were detected in the
patterns
were
Tu0a82-5 and TuOa82-I identified in 1982.
the
sam e
as
30
Site 2j_
Mareth IMrl
At M a r e t h , more duplicate
isolates
were detected
than at any other site (Table 9).
Table 9.
Virulence patterns of five Puccinia horde!
isolates sampled at Mareth, Southern Tunisia,
in 1 983.
Differential Host Genotypes
12 13 Resis1
6
8
10
11
I 2 3 H
5
9
7
Isolate Esta C.Ca Hor Rica Bolivia Quinn Mhgn Peru Suda %yp Batn Gold Reka Genes
RIS
Rag
Bag Bag+ Ra^Rag Pag+Rag IUg IUg IU Pa8 IUg+ IUi,
IUMr 83-10R
TUMr 83-6 R
TUMr 83-2 R
TUMr 83-9 R
TUMr 83-8 R
R
R
R
R
R
R
R
R
s.
R
I
I
R
S .S
R
S
S
S
S
S
R
S
S
S
S
R
S
S
S
I
S
S
S
S
S
S
s.
S
S
I
S
S
I
S
S
S . S
S
S
S
S
S
S
S
S
S
S
S
S
5 26
5 I7
3 I9
3 I9
2 0 11
I Resistance genes: R - resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
The virulence formulae of these isolates showing the
" e f fectiveness/ineffecti veness"
genes
to
leaf
rust
isolates
resistance
of
the
Pa
that
are
indigenous
southern Tunisia are as follows:
I.
TuMr83 -10:
1,2,3,4,5,8,10/6,7,9,11 ,12,13
2.
TuMr83- 6 :
I ,2,3,6,7,11/4,5,8,9,10, 12,13
3.
TuMr83-2:
1,2,3,4/5,6,7,8,9,10,11 ,12,13
4.
TuMr83-9:
I ,2,3,4/5,6,7,8,9,10,11 ,12,13
5.
TuMr83-8:
I ,2/3,4,5,6,7,8,9,10,11 ,12,13
to
31
Common Virulence Patterns Across Regions
The virulence patterns of Puccinia horde! common in
Tunisia are shown in Appendix Table 22.
Table
10 shows
all the duplicate isolates of Pj. hordei that were found
in
at
least
virulence
two
sites
of
collection.
formula, the duplicate
Based
isolates
were
on
the
divided
into five groups.
Group I contains isolates that were found throughout
the
country.
group
is:
The virulence
formula
asociated
with
this
I, 2,3,^/5,6,7 ,8,9,10,11 ,12,13
Group 2 contains leaf rust isolates that are common
in
the
North
formula is:
The
and. Northwest
regions.
The
1,2,4/3,5,6,7,8,9,10,11,12,13
duplicate
isolates
representing
group
isolates that were encountered in the North,
and in the South.
is:
virulence
3 are
Northwest,
The virulence formula for this group
I ,2,3/4,5,6,7,8,9,10,11 ,12,13
The leaf rust isolate representative of group 4 is .
one of the most virulent encountered in this study, and
is
found
throughout
growing areas.
the
country /in almost
all barley
The virulence formula of this isolate is:
I ,2/3,4,5,6,7,8,9,10,11 ,12,13
The fifth group
contains
among these duplicates.
the least virulent isolate
This isolate is found only in
32
the Northwestern
formula:
Table
region and has
the following
virulence
1,2,3,4,5,8/6,7,9,10,11,12,13
10.
Common virulence patterns of Puccinia horde!
isolates in Tunisia in 1982, 1983, and 1984.
______ .
_______ Differential Host Genotypes_________
.
1 2 3 4
5
6
7
8
9
10 11 12 13 Resis1
Isolate Esta C.Ca Hor Rica Bolivia Quinn Nbgn Peru Suda Egyp Batn Gold Rska Genes
Ife3 Phy Pag Pa2+ Ifeg+Pag Pa2+Ifeg Pag Ife2 Pa Pa8 Pa2+ Pazt paP+ R I S
Group I23
5 R
4
R
R
R
S
S
S
S
S
S
S
S
S
409
Group 2^
R
R
S
R
S
S
S
S
S
S
S
S
S
3 0 10
Group 31* R
R
R
S
'S
S
S
S
S
S
S
S
S
3 0 10
Group 4^
R
R
S
S
S
S
S
S
S
S
S
S
S
2 0 11
Group 5^
R
R
R
R
R
S
S
I
S
S
S
S
S
5 I7
1
Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
^ Group I: Isolate identified at Le Kef (1982, 1984), Beja (1982), Mateur (1984),
Mareth (1983), Kairouan (1982).
3 Group 2: Isolate identified at Beja (1982), Nhteur (1982, 1984).
4 Group 3: Isolate identified at Le Kef (1982), Beja (1982), Nfeteur (1983, 1984),
Chsis (1982).
5 Group 4: Isolate identified at Le Kef (1982, 1984), Beja (1982, 1984), Oasis
(1982), Mareth (1983) .
6 Group 5: Isolate identified at Le Kef (1982), Beja (1982).
33
V.
The
results
DISCUSSION
obtained
(Tables
virulence
3 -
types
of
10)
show
the
presence
of several
P_. horde!
Tunisia.
The leaf rust isolates identified within each
site were variable and their virulence patterns
from year to year.
identified
were
al s o
throughout
Some
similar
in at least two
fou n d
the
at
country.
were
Identical
every
studied
site
virulence
patterns changed.
In the Northern region,
most
s p e c i f i c , even
V i r u l e n c e P a t t e r n s of P u c c i n i a
Geographic Regions in Tunisia
isolates
collection
Nonetheless,
isolates
differed
virulence types were
sites.
almost
in
horde!
site
of
the
though
the
in
Various
the two isolates identified
in 1982 at BouRbia differed from all the other isolates
analyzed in this study.
The two isolates have similar
virulence patterns (Table 4).
types on the barley
(Pag).
this
They differed in infection
cultivars Quinn (Pag+Pag) and Magnif
Since the rust collections were made only once at
site,
no speculations can be made as to possible
changes in virulence of these two £_. hprdei isolates.
The virulence
patterns of leaf rust at the Mateur
site varied over years.
in
1 980
was
not
The virulence pattern observed
detected
in
collections
m a d e the
34
following years.
virulent
type
This isolate possibly evolved to a more
following
sexual
recombinations
on the
alternate host, or it was just not detected in the 1 9 8 3
or
1984
samples.
Isolates
identified
in
the
1983
collection were more virulent than the 1980 isolate.
The
virulence patterns of these isolates (Table 4) suggest
that the leaf rust population at this
variable.
not
was
highly
Among the isolates identified in 1984, only
one differed from those of 1983.
may
site
have
been
detected
the
This isolate
previous
(TuMa84-5)
year,
or
it
actually could have been a new virulence type.
The
area
virulence
presents
Theoretically,
pool
of £_. horde!
a potential
danger
to
detected
barley
in this
growers.
barley cultivars that can be cultivated in
this area would be those carrying either or both Pag and
Pa^
resistance
presently
the
hordei isolates
genes.
only
ones
These.two
effective
this
against
4) are
virulent
Pj.
Variability
in virulence of Pi hordei isolates observed
in the North
probably
in
(Table
region.
is most
identified
genes
due to the presence of the alternate
host, Ornithogalu m. Sppi which were found in many barley
fields around Mateur.
In
the
Northwest,
significant
variability
in
virulence patterns of Pi hordei was observed (Tables 5
35
and 6 ).
In Be j a , leaf rust isolates originating
collections
made from Ornithogalum s^Et were as variable
as those
isolated
None
these
of
from
from
commonly
isolates
Virulence
patterns
recovered
in
1984
were
detected
grown
barley
virulent
on
in
1982
collections.
cultivars.
Pag
samples
A possible
or
Pay.
were
not
change
in
virulence of Puccinia hordei could have taken place in
this
ar e a
(Table
5).
At
Le
Kef,
however,
no
major
changes in virulence were observed (Table 6 ).
Pathogenicity
Northwestern
presence
differences
Tunisia
are
of the alternate
in
probably
host,
P^.
hordei
enhanced
particularly
by
in
the
at Beja
where Ornithogalum spp. were found in barley fields.
The
sexual state of E\ hordei on O r nithogalum see, (Table 5),
contributed
to the d i v e rsification of the spectrum
of
virulence of Pi hordei in this region.
The
virulence
Central
Tunisia
identified
types
were
of
leaf
similar
in the Northwest.
rust
to some
encountered
virulence
The isolate
from
in
types
El Jem
(Table 7) was identical to one isolate from Be j a.
The
Kairouan
the
isolate
was
found
in
both
sites
in
Northwest.
In
Southern
Tunisia,
leaf
rust
virulence
varied
almost as much as in the North and Northwest, but fewer
36
virulence patterns were
8 , Table 9).
identified in this region (Table
The microclimate in the Oasis was favorable
for leaf rust development.
In 1984, some barley plots
found in the Oasis, mosaic-type, cropping system,
c ompletely devasted by leaf rust.
were
all
virulent
identified
in
and
identical
I 9 82 (Table
8 ).
were
Isolates identified
to some virulence
Little
types
variability
was
detected in 1984, probably due to the high frequency of
the virulent types.
the
isolates
were
At the other
collected
from
Southern site,
irrigated
Mareth,
barley plots
that were grown as an intercrop in olive orchards.
irrigation created an enviro n m e n t
favorable
The
for rust
d e v e l o p m e n t in 1 9 8 3 , and similar virulence patterns as
those in the Oasis were observed (Table 8 , Table 9)•
intensive agriculture practiced in the
Oasis
The
probably
made it possible for leaf rust to cycle on the primary
host.
Common Virulence Patterns
The Pji, horded, isolate designated "Group 4" (Table
10) was the most virulent isolate identified
in Tunisia.
It was found in all barley g r o w i n g areas in the North,
Northwest and South.
Only Pag and Pay were
effective
against this isolate.
Another leaf rust isolate, Group
3, found in all locations but Central Tunisia, was also
37
virulent on all resistance genes but Pag , Pay, and Pag.
The North and Northwest have a common Pi hordei isolate,
Group
2
(Table
cultivars Estate
(P s 2 +)•
10),
that
is
only
avirulent
on
the
(Pag), Cebada Capa (Pay), and Ricardo
The isolate Group I (Table 10) that is found in
all geographic areas in Tunisia was virulent on all the
genotypes but Estate, Cebada Capa,
Hor 2596,
and Ricardo.
These genotypes and Bolivia were also resistant to the
isolate common to the Northwestern region,
Group 5 (Table
10).
E f f ectiveness of Resistance Genes
Isolates Identified in Tunisia
to Puccinia
hordei
With the exception of Pag and Pay, the frequency of
Pi hordei virulence
against
the
other
Pa genes
varied
from moderate (Pag) to very severe (Pay, Pa, Pag, Pag+)
Although leaf rust isolates virulent
reported (Parlevliet,
on Pay have
been
1981), all Tunisian isolates tested
in this study were avirulent on Pay and on Pag.
The
observed
hordei in Tunisia,
changes
in virulence
should be carefully
favorable climatic conditions,
be expected, especially
if
were grown over large areas.
patterns
monitored.
of Pi
Under
a leaf rust epidemic could
susceptible
barley
cultivars
38
Cultures
genes
of JPi horde i virulent
may be developed
or otherwise,
by recombination
on
Pay
Ornithogalum
but be unable to compete due to associated
factors for non-aggressiveness.
further
on Pa 3 and/or
studied.
This aspect should be
PART
II
NEW SOURCES OF RESISTANCE TO PUCCINIA HORDEI OTTH
IN TUNISIAN BARLEY LAND RACES
Part II
VI.
INTRODUCTION
Barley leaf rust has not been a significant factor
affecting
barley
production
in
Tunisia.
This
favorable
situation may not continue because the disease has. now
been c o m m o n l y observed throughout the country.
Highly
virulent leaf rust isolates, virulent on many sources of
resistance, have been detected
(Part I).
The virulence
types discussed earlier are important since they have not
been
detected
before,
and
they
are
a threat
to
the
commonly grown cultivars.
The search for new sources of resistance among some
Tunisian barley land races led to the identification of
host genotypes which express seedling resistance to most,
if not all,
Morocco,
1984.
Pi h'ordei isolates collected from
Egypt,
This
Jordan,
study
was
and
Syria
carried
out
in
1982,
Tunisia,
1983,
and
to investigate
the
expression and genetic relationships of these unknown
resistance
genes.
HI
VII.
LITERATURE REVIEW
Importance of Barley, in Tunisia
Among
about
1.6
the major
million
crops
hectares.
of Tunisia,
Barley,
cereals occupy
durum
and
bread
wheat are the major cereal crops cultivated. Barley is by
far the best adapted
arid
crop.
regions,
cereal grain in the
but durum
wheat
semi-arid
is the most
to
cultivated
Barley occupies 30% of the cereal production area
and is the main crop in the central and southern regions.
Climatic, conditions
for growing
wheat.
in these
regions
are less
In the northern region,
favorable
barley
is
grown as an alternative crop or in marginal areas, and is
seldom considered as a major crop.
this
region
primarily
have
become
more
Recently,
interested
farmers in
in
barley,
for forage and feed, and also for malting.
to its high
cash value,
malting
important crop in the north,
export commodity.
barley
can
become
Due
an
and could become a potential
If barley production is to be expanded
in these areas, diseases are major risks that need to be
considered.
Disease Problems
The prevalence
observed.
Barley
of barley
Researchers
Project"
have
foliar diseases has been
involved
reported
the
in
the
"Montana-AID
following
diseases
(Table 11) that they have observed during their visits to
Tunisia over a period of eight consecutive years.
Table 11.
Year
Prevalent barley diseases in Tunisia, from
1978-1985, according to observers with the
Montana-AID barley project.
_________ Bariev Diseases^____________
Sc Frr Rn Lr Cs Ls. BYDV Hf Hs others
1978
-
+
+
+
-
+
-
+
+
1979
+
-
+
-
-
+
+
+
+
—
1980
+
+
-
+
-
+
-
-
+
Yr2
1981
+
+
-
-
+
—
—
-
1982
+
+
+
+
-
+
+
+
+
1983
1984
+
+
+
1985
+
+
+
-
+
+
-
+
.
+
+
—
Un^
+
Ps1*
—
—
Observers
Reference
Bocklenm,
Scharen
Snarp,
Sards
Scharen,
Langhans
Chrroll,
fferrabi
Sands,
Ycamt
Sards,
Ruff
Siarp,
Yahyaoui
Carroll,
Grey
Siarp, 1979
Siarp, 1979
Siarp, 1980
Siarp, 1981
Siarp, 1983
Sharp, 1983
Siarp, 1984
Sharp, 19$
i
Nb: Net blotch; Sc: Scald; Frr: Fusarium root rot; Rn: Powdery mildew; Lr: Leaf
rust; Cs: Covered anut; Ls: Loose anut; BYDV: Barley yellow dwarf virus; Hf:
Hessian fly; Hs: Helmintiiosporium stripe
^ Yr: Yellow rust
3 On: Unknown white stripipg disease (10-20% incidence)
” Ps: Pseudomonas svringae
43
Sources of Resistance
The
importance
potential
genetic
of
consequences
base
of
genetic
diversity
associated
cultivated
with
species
and
the
narrowing
has
long
the
been
recognized by plant pathologists and most plant breeders.
One
purpose
evaluate
of testing and screening
germplasm
its reaction to diseases and insect
is
to
pests.
A
decrease in genetic variablity can then be identified and
in
some
Thus,
instances
the
most
can lead to
obvious method
genetic
of
vulnerability.
increasing
genetic
variability, to avoid severe epidemics, is by introducing
germplasm
from
distantly related species into
populations of the cultivated crop.
literature
breeding
In this aspect
reveals many examples of successful
the
transfer
of
disease
resistance
from one
species
to another
;
(Feldman and Sears, 19 81) • It also reveals a wide range
of problems that can arise in interspecific hybridization
(Knot and Dvorak, 1 970; Price, 1979).
Exotic
germplasm . may
contribute
barleys;
positively
in
alternative.
to
cultivation
this
vary
in
its
capacity
to the,improvement of
respect,
land
races
cultivated
could
They offer the advantage of being
even
though some may
have
agronomic traits such as excessive height.,
to
be
an
adapted
undesirable
weak
rachis,
and severe shattering problems.
Land
race
cultivars are found mostly in
parts
of
developing countries where modern high yielding varieties
have
not been introduced.
They are common in the
high
mountains of Ethiopia (Harlan, 1 97 9) , in the Near Eastern
region
(Weltzein and Fischbeck,
southern
Tunisia
and
1 985) ,
in central
possibly in other
North
and
African
countries.
Ethiopian
barleys
have
been a
resistance
to
resistance
in Ethiopian barleys to barley
virus,
many diseases.
useful
Harlan
source
(1979)
reported
yellow
dwarf
powdery mildew, leaf r u s t , scald, and net blotch.
Kelemu
(1984)
found
new
resistance
genes
Rhynchosnorium secaIis in Ethiopian barleys.
that
of
the
breeding
populations
genetic
of
It appears
cultivated
variability
to
encompass
great
exploited.
There are 18,000 entries of barley catalogued
in the world collection (Reid and Wiebe,
available
collection,
for
332
barley
resistance
communication).
Twenty
powdery mildew (Reinhold,
sites
be
Out of
lines were screened
at both
can
1979) currently
use by barley researchers.
reaction in California and Montana.
showed
that
barleys
for
this
scald
A total of 131 lines
(Bockelmah,
three lines were
personal
resistant
personal communication).
to
Ten
45
of
these lines were resistant to both powdery mildew and
scald.
Inheritance and resistance genes in barley.
In
the early 1900’s,
absence
Biffen demonstrated that
of stripe rust on a host plant was an
character.
This
successful
was
programs
investigator
to
dominant
factor.
found that all genes conditioning
resistance
Watson and Butler (in Roane,
that resistance to leaf
varieties
rust
in
several
was conditioned by independent
genes.
Recently several major genes for resistance to leaf
(PjL
hordei)
have
been described (Roane
I 967 ;
Clifford,
These
genes are designated Pa,
assumed
to
to
cultivars,
showed
barley
first
between resistant barley
occurred at the same locus.
1962)
the
He found that resistance in several
crosses
Waterhouse
to
1962) was the
was conditioned by a single
in
and
study the inheritance of resistance
leaf rust in barley.
Later,
great
of breeding for resistance
Waterhouse (in Roane,
cultivars
inherited
the beginning of many
rust fungi.
the
1974;
operate
and
Starling,
Parlevl^et, I 976 and Tan,
on
a
Pag,
Pag etc.
gene-for-gene
rust
I 977).
and
basis
are
with
corresponding virulence genes in the pathogen.
Early genetic studies of host reaction to P..
were
re-evaluated
by Roane and Starling
(1970).
hordei
They
proposed the gene symbols Pa,
Parlevliet
"Gondar",
,carried
(1976)
Pa2 ,
concluded
Pag,
that
Pay,
barley
and Pag.
cultivars
"La Estanzuela", "Cebada Capa", and "Dabat" all
the Pay resistance gene.
This was confirmed by
Clifford a n d 'Udeogalanya (1976).
Effectiveness of the Pa Genes
Virulence on barley cultivars having the
resistance
(Pa) genes occurs widely in Europe (Clifford , 1974).
Pay gene is effective throughout Europe,
against
Pag
occurs
rather
The
while virulence
infrequently
(Parlevliet,
1 976).
Studies of virulence in British populations of £.*.
horde!
revealed widespread virulence to host
■genes Pa,
(1982)
Pa2 ,
showed
resistant
Pag,
and Pag.
Sharp and Reinhold
that barley lines with Pag
or
Pay
area.
They
also identified
two
the
barley
that did not possess Pag or Pay but were resistant
to all the '12 isolates.
Pag was overcome by one isolate
originating from the alternate host (Sharp and
1982).
were
to 12 isolates from the United States and
Mediterranean
lines
Pay,
resistance
Clifford
and
Udeogalanya (1976) have
differential response given by Cl 1243,
Reinhold,
observed
the Pag carrier.
Pretorius and Wilcoxson (1983) showed that Pag,
Pay, and
Pag were effective against all races of Pj. hordei
known
to
occur
in
incorporating
the
United
these
States.
They
genes into cultivars grown
upper midwest to eliminate the potential
rust
in
recommended
this region.
in
the
threat of
leaf
Two cultivars with the Pa^
gene
(Monroe, Cl 1 5691 and Henry, Cl 15690) have been released
and
are
still
showing good
personal communication).
field
resistance
(Roane,
VIII.
MATERIALS AND METHODS
Parent Selection
Single heads of I 80 barley land race cultivars were
collected from f a r m e r ’s fields in central and southern
Tunisia.
They
isolates
Thirty
of
four
were
screened
Pj. horde!
lines
from
showed
for
the
their
reaction
Medite r r a n e a n
i n t ermediate
reaction to most of the Pi hordei isolates
to
to
area.
resistant
tested.
Five
of these barley cultivars were selected and seeds from
single heads were multiplied in the field.
the off-types were rogued.
row was bulked.
At maturity,
Harvested seed from each head
These lines were given a Tu (Tunisian)
number and were further screened against various isolates
o f Pi hordei.
Selected lines (Tu I6 , T u 17, Tu 27 , Tu32, Tu3 4; Table
1 2 ) were crossed with four differential genotypes with
kno w n resistance
completely
Pa genes.
susceptible
Reka I (Pag+,
Cl 5051) was
(IT:4) to Pi hordei isolates,
and
was used as the susceptible parent. Parents and five to
ten
F 1 seeds
were
planted
in
Tucson,
A r i z o n a , where
backcrosses and additional single crosses were made.
backcrosses and Fg hybrids
The
49
Table 12.
Land race barley cultivars used in this study
and their site of collection in Tunisia.
Cultivar
Site of Collection 1
Tu
Tu
Tu
Tu
Tu
16
17
27
32
34
1
see Appendix Figure 15.
were
Year
Gafsa - Central Tunisia
Oasis - Southern Tunisia
El Jem - Southeast Tunisia
El Jem - Southeast Tunisia
El Jem - Southeast Tunisia
later
screened
in
I 982
1982
I 983
1983
1983
environmentally
controlled
growth
chambers.
Inoculum and Inoculation Techniques
Inoculum from the three selected isolates (TuKe82-5,
Tu0a82-1 ,
MoMe84-5)
susceptible
was
cultivar
multiplied
Moore
(Cl
on
725).
the
universal
Isolates
were
separated from each other and kept in different growth
chambers
Screening
to
minimize
the
chances
of the hybrids and parents
of
contamination;
was conducted in
three separate growth chambers maintained at the same
temperature and photoperiod regimes as discussed in Part
I.
Inoculation procedures were the same as discussed in
Part I , with the following exception; due to the large
50
number of plants screened, the rust spores were suspended
in Soltrol
170 oil in a ratio of I mg spores/ I ml oil.
The spore suspension was then sprayed on the plants to be
screened,
using
a
compressed
air hose
DeVilbiss
attached
to
a
(I5 - 2 0 ps.i).
Hybrids and parents
mixture.
atomizer
were g r o w n in a 2:1 s o i l :sand
Two hundred F g seedlings of each cross were
planted in metal flats (34cm x 25cm x 8 cm).
They
were sown in eight rows of 25 seeds per row.
the universal susceptible,
Parents,
back crosses, and Fg seedlings
were planted in plastic pots (10 cm diameter).
Parents
and hybrids that were to be transplanted into the field
for seed production of the successive generations (ie.
F2 ;
F3 ,
and
seeds/pot).
seedlings
BCFg)
were
Following
were
planted
seedling
sprayed
with
in
disease
peat
pots
(5
assessment,
the
following
the
Bayleton
removal of the heavily infected leaves.
Only one plant
was kept in each pot and was then transplanted into the
field.
F g transplants
their disease reaction,
were
color-coded
according
and marked in the field.
to
Thus
the reaction type of the Fg generation could be traced
back to the reaction type of individual selfed Fg plants.
The
advanced
generation
(Fg)
and
some
Fg s
that
were
transplanted, but matured late, and had to be harvested
51
before reaching physiological
maturity.
Hence,
their
germination was poor.
Since
the Pj. hordgi isolates used in this study were
of foreign o r i g i n , all the plant material and soil were
autoclaved following each experiment.
Statistical Analysis
The
probability
values
for
expected ratios were calculated
goodness
of
using Chi-square
fit
to
method.
In both F 2 and F g progenies, where more than one F^ plant
was studied,
to determine
a Chi-square
whether
different
similar genetic behavior.
the
tables.
test for homogeneity
F g families
was used
displayed
Combined data are presented in
52
IX. RESULTS
Parents
The
five
land
race
barley
cultivars
selected
for
this study had outstanding resistance to almost all of
the Pj. horde! isolates from the Mediterranean region and
specifically those identified from Tunisia, in 1982, 1983
and
1984.
these
cultivars
hordei.
invariably
were
Evidence presented (Table 13) suggests that
Their
carry
reactions
associated
normally
P a g , Pa7 ,
may
with
new
to
different
some
distinguishable
resistance
isolates
chlorosis
from
those
genes
to JPjl
were
a n d , as such,
conditioned
by
and Pag and for that matter those typical to
Pa, Pa 2 , Pa lf, Pa 2 +, P a 2 + P a ^ , Pa2 + Pag, and Pag.
Table 13
shows the reaction patterns of nine Pjs. horde! isolates
that were observed on these selected cultivars.
The three isolates TuKe82-5,
were
collected
(Morocco),
and
from
the
Le
Oasis
Kef
MoMe84-5,
and Tu0a82-1
( Tunisia) ,
(Tunisia).
Their
Merchouch
virulence
patterns on the differential set are shown in Table 14.
53
Table 13.
Reactions of five Tunisian barley lines and
four differential barley genotypes to nine
Puccinia
horde!
isolates
from
several
locations.
i
ICU
I<n
13 1
IEH
I
ItICM
I3 I
IEH
I
_Barley_Genotypes--Isolate s ^ Reka Hor2 5 96 Est CCapa Tu 16 Tu17
Pa3 Pa7
. Pa2 + Pa9
I
2
3
4
5
6
7
8
9
TuMa83-l6
TuKe82-5
Tu0a82-1
MoMe84-5
MoRb 84-1
JoAm84-4
SyAl84-1
EgGg 84 - 1
EgSk84-1
S2
S
S
S
S
S
S
S
S
R
R
S
I
R
S
I
S
R
I
R
S
R
R
R
R
S
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
R
R
R
R
R
R
R
R
R
R
R
R
R
Tu 34
I Isolates I, 2 , 3 are from Tunisia; 4 , 5 from Morocco; 6
from
Jordan, 7 from Syria, and 8, 9 from Egypt.
2 R = r esistant reaction,
reaction
I =Intermediate,
S = susceptible
Virulence patterns of three Puccinia h o r d e i
isolates on barley differential eultivars.
Differential Host Genotvnes
12 13
10 11
9
7
8
4
5
6
2
I
3
Reka
Egyp
Batn
Gold
Magn
Peru
Suda
Rica
Bolivia
Quinn
Hor
C.Ca
Isolate Esta
Pa1
,
Pa
Pa2+
Pa2+Pag
Pa2+Pa
Pa3 Pa7 Pa9
Pa2+
Pa8 Pa2+
5 Pa5 Pa2
Table I 4 .
TuKe82-5 R1 R
MoMe84-5 R R
TuOa82-I R R
R
R
S
R R
S R
S S
R
R
S
R
S
S
S
S
S
R
R
S
S
S
S
R
R
S
S
S
S
S
S
S
I R = resistant reaction, I = intermediate reaction, S = susceptible reaction
54
The avirulence/virulence formulae of these isolates
were
as follows:
TUKe82-5
1,2,3,4,5,6,7,9,11/8,10,12,13
MoMe84-5
1,2,3,5,6,9,11/4,7,8,10,12,13
Tu0a82-1
I ,2/3,4,5,6,7,8,9,10,11 ,12,13
Isolate
study
Tu0a82-T was particularly virulent in
since
only two resistance
against it.
since
were
effective
TuKe82-5 and MoMe84-5 were largely avirulent
more resistance genes were effective against them.
Resistance
were
genes
this
factors associated with land
race
cultivars
effective against these isolates with the exception
of the resistance factor in Tu 16 which was not
against Tu0a82-I .
effective
The avirulence/virulence formulae for
these lines are:
TuKe82-5
-/Tu I6,Tu 17,Tu27,Tu32,Tu34
MoMe84-5
-/Tu I6,Tu 17,Tu27,Tu32,Tu34
Tu0a82-I
Tul6/Tu17,Tu27,Tu32,Tu34
When
land
race cultivars were crossed with
genotypes having specific resistance genes,
segregated
the
in the F 2 generation indicating the
barley
progeny
presence
of different resistance genes or gene combinations.
Data
pertinent to these crosses were divided into two groups:
55
1.
Tho s e
from
crosses
of
resistant
land
race
cultivars with the susceptible parent RekaI, to determine
the numb e r of gene loci for resistance in each cultivar
(Table
15).
The following crosses were made:
Tu16 x RekaI
Tu32 x RekaI
Tu 17 x RekaI
TuS1J x RekaI
Tu27 x RekaI
2.
Those from crosses b e t w e e n the resistant land
race cultivars and
2596,
E s t a t e , and
the
three
Cebada
resistant genotypes
Capa)
with
known
(Hor
resistance
genes, to determine if the genes for resistance are at a
common
locus (Tables
16,
17,
18).
The following crosses
were made:
Tu I6 X H'or2596
Tu I6 X Estate
Tu 16 x Cebada Capa
Tu I7 X Hor25 96
Tul 7 X Estate
Tu I7 x Cebada Capa
Tu 27 X Hor2596
Tu27 X Estate
TuB 2 X Hor25 96
TuB 2 X Estate
TuB1J X Hor2596
TuB1J X Estate
56
Table
15.
Cross
The reaction of Fg barley seedlings to three
isolates
of
Puccinia hordei (RekaI x
five
land races).
Parental
Observed Freauencv
reaction1 Isolate
resis.
susc.
Expected
Probability
ratio
Tul6 x RekaI
Tul6 x RekaI
Tul6 x RekaI
R/S
R/S
S/S
TuKe82-5
MoMe8*1-5
TuOa82-1
154
156
116
452
459
410
1:3
1:3
1:3
.85
. .87
.13
Tu17 x RekaI
Tu17 x RekaI
R/S
R/S
TuKe82-5
Tu0a82-1
392
371
142
126
3:1
3:1
.42
.89
Tu27 x RekaI
Tu27 x RekaI
R/S
R/S
TuKe82-5
TuOa82-1
155
. 164
52
58
3:1
3:1
1.00
.76
Tu32 x RekaI
Tu32 x RekaI
R/S
R/S
TuKe82-5
TuOa82-1
218
175
68
67
3:1
3:1
.68
.37
Tu34 x RekaI
Tu34 x RekaI
R/S
R/S
TuKe82-5
TuOa82-1
535
66
182
25
3:1
3:1
.84
.67
Reaction of first parent/second parent; R = resistant, S = susceptible.
57
Table 16.
Cross
The reaction of Fg barley seedlings to three
isolates
of Puceinia horde! (Hor 2596 x five
land races) .
Parental
reaction^
Isolate
Observed Freauencv
resis,. SUSC.
Expected
ratio
Probability
Tul6 x Hor2596 R/R
Tul6 x Hor2596 R/R
Tu16 x Hor2596 SZS
TuKe82-5
MoMe84-5
TuOa82-1
455
313
307
101
2l»2
225
13:3 ,
(9:7)2
(9:7)
Tu17 x Hor2596 R/R
Tu17 x Hor2596 R/R
Tu17 x Hor2596 R/S
TuKe82-5
MoPfeSlf-S
TuOa82-1
720
721
762
39
51
2H3
15:1
15:1
3:1
.23
.73
.57
Tu27 x Hor2596 R/R
Tu27 x Hor2596 R/S
TuKe82-5,
TuOa82-I
333
72
27
17
15:1
3:1
.38
.2if
Tu32 x Hor2596 R/R
Tu32 x Hor2596 R/S
TuKe82-5
TuOa82-I
168</
209
15
43
15:1
13:3
.35
.5H
Tu3% x Hor2596 R/R
Tu34 x Hor2596 R/S
TuKe82-5
TuOa82-1
176 ;
IlfO
16
50
15:1
3:1
.30
.73
1
2
.76
1.00
.53
Reaction of first parent/second parent; R = resistant, S = susceptible.
Ratios in parentheses were not expected, but gave the best fit.
58
Table
Cross
17.
■The
r e a ction
isolates
of
land races).
Parental
reaction^
Isolate
of Fg barley seedlings to
three
Puccinia horde! (Estate
x
five
Observed Freauencv
resis.
susc.
Expected
ratio
Probability
Tul6 x Estate R/R
Tul6 x Estate R/R
Tul6 x Estate S/R
TuKe82-5
MoMe84-5
Tu0a82-1
561
628
527
122
157
163
13:3
13:3
3:1
.58
.39
.43
Tu17 x Estate R/R
Tu17 x Estate R/R
Tu17 x Estate R/R
TuKe82-5
MoMe84-5
TuOa82-1
710
642
377
46
46
22
15:1
15:1
15:1
.91
.69
.61
Tu27 x Estate R/R
Th27 x Estate R/R
TuKe82-5
TuOa82-1
53
158
6
15
15:1
15:1
.32
.25
Tu32 x Estate R/R
TuB2 x Estate R/R
TuKe82-5
TuOa82-1
77
162
2
0
(15:1)2
no seg.
.26
TuB1J x. Estate R/R
TuKe82-5
317
14
15:1
.16
I Reaction of first parent/second parent; R = resistant, S = susceptible.
2
Ratios in parentheses were not expected, but gave the best fit.
59
Table
18.
The
r e a c t i o n of Fo barley seedlings to
three
isolates of P u c c i n i s horde! (Cebada Capa x two
land r a c e s ) .
Parental
reaction^
Cross
Cbserved Freouencv
SUSC.
resis.
Isolate
Expected
ratio
Probability
Tul6 x C.Capa R/R
Tul6 x C.Capa R/R
Tu16 x C.Capa S/R
TuKe82-5
MoMe84-5
TuOa82-1
4YY
YYO
252
90
61
Yl
13:3
15:1
3:1
.26
.22
.23
TuIY x C.Capa R/R
TuIY x C.Capa R/R
TuIY x C.Capa R/R
TuKe82-5
MoMe84-5
TuOa82-1
640
552
565
O
O
34
no seg
no seg
15:1
-
-
CM
VO
I Reaction of first parent/second parent; R = resistant, S = susceptible.
Segregation in Jesistant x Susceptible crosses
Segregation
susceptible
parent,
are
cultivars
to
isolates
be
F2
13).
involving
and five land
in Table 15.
moderately
(Table
the
RekaI,
shown
cultivar RekaI,
of
of the crosses
to the virulent isolate
susceptible
found
results
resistant
race
the
When crossed to the
was
other
two
susceptible
the Chi-square test for goodness of
progeny
gave
a
good
fit
was
it
TuOAa82- I ,
to
barley
Tu I6
Although
the
to
a
fit
1:3
(resistant:susceptible) ratio regardless of the virulence
type
of
obtained
the
when
(Figure I).
isolate
tested.
inoculated
with
Resistant
the
plants
virulent
were
isolate
60
With
the crosses involving RekaI and the other four
land race cultivars (Tu 17 »
progeny
Tu27 >
Tu32, and TuS1*) the F g
fit a 3:1 ratio (Table 15)
when tested
both the avirulent and the virulent isolates.
crosses,
as
against
In
these
almost all the plants, of the population reacted
resistant or susceptible to the Pj.
horde!
isolates.
(Figs. 2 , 3 , 4 ) .
Segregation in Resistgnl x Resistant Crosses
With
carrier
crosses
of
ratios
involving
barley
resistance, gene Pag,
cultivar
different
in the F2 progeny were observed,
Hor2596,
segregation
some
of
which
were not expected (Figure 5).
The
F2 progeny of (Tu 16 x Hor2596) segregated in
a
13:3 ratio when tested with the avirulent isolate TuKe825,
and
with
yet
the .avirulent and virulent isolates
Tu0a82-1 ,
not
which
gave a good fit to a 9:7 ratio when
respectively (Table 16) .
expected,
both
tested
MoMe84-5
and
The observed 9:7 was
especially with the virulent, isolate
parents were susceptible, . and
to
furthermore,
Tu 16 probably has a resistance ge n e .
Even though Hor2596
has
Pag
the
dominant
Ddeogalanya,
1976),
resistance
this
gene
gene
was
(Clifford
not
and
effective
61
TUie X REKA
550
MoMe84-5
re
D iI e a s e
r e a c stuisocne p t i b l e
Frequency distribution of F^ barley seedlings
to t h r e e i s o l a t e s of
h o r d e i ( T u I6 x
RekaI).
Figure I
TU17 X REKA
450i
□ TuKe82—5
T u Oa82-l
I
I
R E DISEASE REA
Figure 2
SUSCEPTIBLE
Frequency distribution of Fg barley seedlings
to two isolates of Pi hordei (Tu 17 x Rekal).
62
O TuKe82-5
T1127 X REKA
mD TuOe82-l
RESISTANT
SUSCEPTIBLE
DISEASE REACTION
Figure 3.
Frequency distribution of Fg barley seedlings
to two isolates of
horde! (Tu32 x Rekal).
□ TuKe82—5
TU34 X REKA
am TuOa82-l
RESISTANT
SUSCPTIBLE
DISEASE REACTION
Figure 4.
Frequency distribution of Fg barley seedlings
to two isolates of Pi hordei (Tu34 x Rekal).
63
TU16
RESISTANT
SUSCEPTIBLE
DISEASE REACTION
Frequency distribution of F g barley seedlings
to t h r e e i s o l a t e s of Pjl h o r d e ! ( T u I6 x
Hor25 96) .
Figure 5
8001
TU17 X HOR2596
B HoHlil=I
TuOaS2-I
>
I
a
o
Figure 6
HE|iliSgl REACsTu1
sOcMep11ble
Frequency distribution of Fg barley seedlings
to t h r e e i s o l a t e s of P . h o r d e ! (Tu I 7 x
Hor2596 ) .
against
would
Tu Oa 82 -1
Pj. horde!
not be expected
Hor25 96 cross.
Since
isolate,
thus
in the F 2 progeny
a 9:7 ratio
implies
dominant gene action involving two genes,
a 9:7
ratio
of the Tu 16 x
complementary
this would not
be the case in this particular cross.
In
crosses
involving
cultivars T u 17, Tu 27,
the F 2 progeny
and
Tu32 and Tu3%
the
land
race
(Figures 6, 7, 8),
fit a 15:1 and a 3:1 ratios when tested
with the avirulent isolate
isolate
Hor 2 5 96
TuKe 82-5,
Tu Oa 8 2 - I , r e s p e c t i v e l y
and the virulent
(Table
I 6).
The
F2
progeny of (Tu 3 2 x Hor25 96) fit a 13:3 rather than a 3:1
ratio when tested with Tu0a82-1
(Table 16, Figure 8).
The cultivar Estate has the dominant resistance gene
Pag
(Roane
against
and
all
Starling,
P^
horde!
1970)
which
isolates
(Part
was
effective
I).
Crosses
involving this cultivar and five resistant land races are
shown
in Table
17.
The F 2 progeny
of (Tu 16 x Estate)
segregated in a 13:3 and a 3:1 ratio when tested with the
avirulent and virulent isolates respectively
The F 2 progeny resulting from
being
Figure
crossed
10,
to
11,
Estate,
12).
In
fit
the
a
Tu17,
15:1
Tu27 and Tu34
ratio
F 2 progeny
(Figure 9) •
(Table
of
17,
(Tu 3 2 x
Estate), there were no susceptible plants detected when
65
200
XU34 X HOR2596
□ TuKe82-5
mD TuOa82-l
I
I
re
D iI e a s e R e a c t 1
IsO n ipt 1BLE
Figure 7 . Frequency distribution of F 2 barley seedlings
to two isolates of Pi horde! (TuB1J x Hor25 96).
250
__________ T1132 X HOR2596
O TuKe82-5
m TuOa82-l
>
3
g
0
Figure 8.
Frequency distribution of F2 barley seedlings
to two i s o l a t e s of Pi horded. ( T u 3 2 x
Hor2596 ) .
66
Tlllfi V
Figure 9.
EfiTATV
Frequency distribution of F2 barley seedlings
to thr e e i s o l a t e s of P_j_ h o r d e i ( Tu I 6 x
Estate).
750
Till? X ESTATE
] TuKel2-5
ED Tu0*82-1
KEACsTuIsOcNe
Figure 10.
Frequency distribution of F2 barley seedlings
to t h r e e i s o l a t e s of Pj. h o r d e i ( T u I 7 x
Estate) .
200
T 1127 X E S T A T E
-□ TuKe82-5
HI TuOa82-l
>
i
a
I
k
0
'•ttSigSl REACTIONptikle
Figure 11
Frequency distribution of F2 barley seedling
to two isolates of P. hordei (Tu27 x Estate)
200
TU32 X ESTATE
□ T uKe82-5
ED TuOa82-l
I
I
REd i ! e a s e
Figure 12
r e a c stuisocne p t i b l e
Frequency distribution of F2 barley seedlings
to two isolates of P. Aordei (Tu32 x Estate).
68
tested with the virulent isolate (Figure 12).
However,
a
good fit to a 15:1 ratio was observed when the F 2 progeny
was tested with the avirulent isolate (Table
latter
ratio is questionable
plants in the susceptible
from
due to the low
class
misclassification
or
which
mixed
17).
number of
may have
seed.
The
resulted
Since
segregation was observed with the virulent isolate,
no
this
result was not expected with the avirulent isolate.
Crosses
Cebada
Capa
were also made
with
the resistant
cultivar
which is resistant to all Pi horde! isolates
w o r l d w i d e (P a r l e v l i e t , 1 976 ; Reinhold and Sharp, 1 982).
The
results
pertinent
to the crosses involving Cebada
Capa are shown in Table 18.
Cebada
Capa)
gave
ratio when tested
respectively
a good
with
(Figure
The F 2 progeny
fit
to
a 13": 3,
TuKe82-5, MoMe84-5
13).
No susceptible
of (Tu 16 x
15:1
and
and
3:1
Tu Ca 82-1,
plants
were
observed in the F 2 progeny of (Tu 17 x Cebada Capa) when
tested with the avirulent isolates,
however a good fit to
a 15:1 ratio was observed when the F2 progeny was tested
with the virulent isolate (Table 17, Figure
IiI).
69
850
TU16 X CEBADA CAPA
I
a
o
E
0
REdiIease reacstuisocneptible
Figure 13•
Frequency distribution of Fp barley seedlings
to three isolates of Pjl horde! (Tu 16 x Cebada
Capa).
TU17 X CEBADA CAPA
S
k
EII=!
5
I
SUSCEPTIBLE
R E DII EASE REACTION
Figure IiJ.
Frequency distribution of F- barley seedlings
to three isolates of Pi hordei (Tu 17 x Cebada
Capa).
70
Segregation in
and backcross generations^.
To further verify the hypotheses stated for the F 2
r a t i o s , the
RekaI
were
Table 19.
Fg
backcross
TU16 x RekaI
TUI6 x RekaI
TUlGxRekaIZRekaI
TUl6xRekaI/TUl6
TU16 x RekaI
TU16 x RdcaI
in crosses
with
The reaction of barley seedling progeny to two
isolates of Puccinia hordei
(RekaI x five
land races) .
S1
BCp
F3
4
Tu17 x RekaI
TU17 x RekaI
TU17xRekaI/Tu17
TU17xftekaI/TU17
TU17 x RekaI
TU17 x RekaI
pi
Tu27 x
TU27 x
TU27 x
IU27 x
RekaI
RekaI
RekaI
RekaI
pi
TU32 x RekaI
TU32 x RekaI
pi
Meal
RekaI
RekaI
RekaI
hybrids
tested (Table 19).
Parental
GerBration reaction1 Isolate
Cross
Tu34 x
U i34 x
TU34 x
TU34 x
and
%
BCp
Po
fI
P3
p3
']
Observed Frequency Ebcpected
resis. segreg. susc. ratio
Prdaability
R/S
S/S
E/S/S
R/S/S
R/S
S/S
TUKe82-5
TUOa82-1
TUKe82-5
TUKe82-5
TuKe82-5
TUC&82-1 '
12
12
8
R/S
R/S
R/S/R
R/S/R
R/S
R/S
TUKe82-5
TU0a82-1
TUKe82-5
TUC&82-1
TuKe82-5
TUC&82-1
R/S
R/S
R/S
R/S
R/S
R/S
R/S
R/S
R/S
R/S
24
24
19
10
19
15
17
13
13
19
15
18
8
16
-
-
12
26
2
13
lUKe82-5
TUC&82-1
TUKe82-5
TUC&82-1
10
9
11
10
19
13
13
4
TuOa82-1
TUQa82-1
10
16
_
—
28. . 15
TuKe82-5
TUC&82-1
TuKe82-5
UiChSB-I
9
10
12
3
0:1
1:1
1:2:1
1:8:7
1.00
.70
.49
.03
1:0
1:0
1:2:1
1:2:1
1.00
1.00
.17
.78
1:2:1
1:2:1
.68
.25
1:2:1
.91
1:2:1
1:2:1
.78
.46
-
-
-
22
24
14
5
1 Reaction of first parent/second parent; R = resistant, S = susceptible.
71
The
Fg
progeny
in
(T u I6
x
R e k a I ) fit
a
"one
resistant: two s e g r e g a n t s :one susceptible" (1:2:1) when
tested with the avirulent
isolates.
The Fg progeny of
(Tu 16 x Rekal), when inoculated with the virulent Tu0a821 isolate, did not fit the expected
1:8:7 ratio. The F^
progeny of this cross was susceptible and when crossed to
the resistant parent
r a t i o , howe v e r
(BCg) it gave a good
when crossed
fit to a 1:1
to the susceptible parent
(BC1) a 0:1 ratio was observed.
The Fg progeny of (Tu 17 x Rekal) fit a 1:2:1 r a t i o ,
and
a
1:0
ratio
was
observed
in
B C 1,
and
BCg-
A
segregation ratio of 1:2:1 was also observed in the Fg
progeny
Rekal).
of (Tu27 x Rekal),
(Tu3 2 x Rekal)
and
(TuS1I x
72
X.
Many
varieties
DISCUSSION
of
land
races
of barley
gro w n
in
central and southern Tunisia have an adequate level of
resistance to the leaf rust pathogen.
In these remote
areas of Tunisia there have been no planned programs
breeding
for
resistance
to
pest.s
or
to
other
for
stress
tolerances such as, drought t o l e r a n c e , heat t o l e r a n c e ,
cold tolerance,
salt tolerance etc.
The barley cultivars
grown in these regions are often mixtures of heterogenous
genotypes that have been either discarded from commercial
production over the y e a r s , or are collections of seeds
that
have
been
exchanged
for
other goods
among
tribes along the southern parts of North Africa.
alternative
is
that
the
seeds
were
handed
nomad
Another
down
from
generation to generation within the farming community in
these
regions.
The mixed barley cultivars or land races, regardless
of
their
resistance.
origin,
cou l d
Incorporating
become
a
useful
this valuable
source
material
of
into a
breeding program should be a relatively easy task since
there
should
abnormalities
be
no
that
problems
would,
of
occur
sterility
in
or
other
interspecific
73
hybridization.
Furthermore
undesirable agronomic
that are usually derived from
wild relatives, do not have
to be bred out when using land races.
little
attention,
It appears that
if a n y , has been paid to the direct
exploitation of land
investigation,
traits
race
cultivars.
In this
present
it can be seen that from the screening of
a few land race barley cultivars collected over a short
period
of time,
an adequate source of resistance to Pj.
hordei and maybe resistance to other plant pathogens,
present
and could
easily be exploited.
was
The five land
races studied in this investigation were shown to have a
good
level
of resistance
to
Pjl hor d e i , which
was
far
better than that of the present commercially grown barley
cultivars in Tunisia,
and probably in other regions of
the world as well.
In this investigation an attempt was made to study
the
genetics
respect
of
to their
resistance
reaction
in
these
cultivars
to Pli hor d e i .
Crosses
with
were
made between barley genotypes with four known resistance
genes,
and
resistance
five
land
factor(s)
recessive, and
or many genes.
races,
in these
to
lines
determine
were
if
dominant
the
or
whether they were controlled by one, few,
74
For the purposes of this study , the three Pjl horde!
isolates
differed
allowed
used
to
test
the
segregating
in their virulence.
The avirulent
the detection of the largest
resistance
gene(s),
whereas
populations
the
isolate used
possible
number
diff erentially
of
virulent
isolate allowed further classification of the segregating
progenies
to
e mphasize
that
pathogen
be
made.
It
a particular
is
important,
isolate
though,
of the
to
Pj. horde!
may be comprised of different genotypes.
genotypes have only one essential factor in common,
These
which
is the possession of a virulence gene able to overcome
resistance
controlled
by a corresponding
gene
in
the
host.
Thus a single isolate may consist
of individuals
which
have
but
virulence
a virulence
to other host
gene
in
common
cultivars
with
other
differ
in
resistance
genes.
It must be e mphasized that the result of cultivar
inoculation with a specific isolate of the pathogen is an
interaction of c orresponding resistance and avirulence
genes giving an infection type.
to
some
degree
of
corresponding genes
This in turn,
resistance.
in the pathogen
If
the
gives rise
critical
are virulent,
the
host is susceptible regardless of whether or not it has
resistance
genes
(Appendix,
Table
23)»
cases
of
75
quantitative inheritance, several interacting genes in
both
the
host
and
pathogen
may
be
required
effective resistance
(Appendix, Table 24).
is
this
used
throughout
thesis
in
to
give
This premise
interpretation
of
results.
In crosses with the susceptible cultivar Re k a I , a
m onogenic mode of inheritance was suggested,
avirulent
isolates.
Fg and backcross results
support this hypothesis.
complex)
Pag+,
with the
which,
(Table
RekaI has a dominant gene (gene
even
though ineffective against
a vast majority of the Tunisian isolates (Appendix,
2 2),
was
found
■hordei isolate
1982).
to
confer
from
resistance
Sakha,
Egypt
the
resistant
Nevertheless,
could be due to a dosage effect.
RekaI and
Tu 16 interacted
conditioned resistance
19)
Table
to a virulent
(Reinhold
and
reaction
Pjl
Sharp,
detected
Resistance genes from
in a complementary
to the virulent
manner and
Tu Oa 82-1 isolate.
It appears that two dominant alleles at one locus and at
least one dominant allele for resistance at another locus
were
required
to counter
Tu Oa 8 2 - 1 isolate.
the virulence gene(s)
It could
be possible
that
in the
the Pa 2 +
gene complex in RekaI contributed to the resistance in
the segregants of (Tu I 6 x Rekal).
been
due
to
some
other
factors
This also could have
in
the
background
of
76
either parent, such as the.presence of minor genes.
In
the
interaction
1:3 F 2 ratio.
This
inadequate F2 family
in
disease
(T u I 6 x
Rek a I ) with
the
F 3 data (Table 19) failed to confirm
virulent isolate,
the
of
could
sample
have been due
sizes
classification.
to either
or experimental
More
data
are
error
needed
to
either c onfirm the F 2 ratio proposal or another mode of
inheritance.
When
the r emaining
crossed to Rekal,
F2,
Fg,
and
four land race cultivars were
the segregation ratios observed
BC
generations
inheritance pattern.
implied
a
in the
monogenic
These cultivars could be considered
as carriers of a dominant resistance gene.
The results presented for the F 2 progenies
from the
crosses of the five land race cultivars to four barley
differentials
the
with
resistance
known
genes
resistance
in the
land
genes,
race
suggest
that
cultivars
were
different from the Pa3 , Pay, and Pag resistance genes.
The resistance gene in the cultivar Tu 16 appears to
be
ineffective
against
the
virulent
isolates,
but
effective against the avirulent ones. Evidence of this
was
presented
(Tu 16 x Cebada
with
the data
Capa),
from
especially
(Tu I 6 x Estate)
and
if one contrasts
the
reactions of the F 2 progenies that resulted when tested
77
with
the
a v i r ulent
isolates.
TuKe82-5
A monogenic
mode
with the virulent isolate.
was
ineffective
complementary
against
manner
and
virulent
of inheritance
was observed
The resistance gene in Tu 16
T u 0 a 8 2 - I but
with
Tu Oa 8 2 - I
interacted
Pag in the presence
in a
of the
avirulent isolates. In (Tu 16 x Hor25 96), a 9:7 ratio was
unexpectedly observed in the Fg progeny.
Hor2596 has the
single dominant gene, Pag, which is temperature sensitive
(Clifford and
Odeogalanya , 1976).
Temperature
could have
had an effect on the hybrid progeny, especially
when Pag
was in a different genetic background other than that of
Hor 2 5 96 .
A l s o , not
enough
is
known
conclusively attribute its resistance
gene.
Minor
genes
could have affected
expression
of
maybe
present
genes.
Tu I 6 to
to solely a single
in both
reactions of progeny.
major
about
There
parents
and
Thus altering
was
also
the
possibility of accidental seed mixture or impurity of the
parental
seed source.
Results
of testing F g progeny
of T u 17,
Tu 27,
and
Tu 3 W crossed to either H o r 2 5 9 6 or Estate, suggested the
presence of a d omi n a n t gene in each of these cultivars.
These genes were also different from Pag and
likewise
possessed
a
dominant
Pag.
resistance
suggested by the F g progeny (Tu32 x Hor2596).
Tu32,
gene
as
However,
78
no susceptible plants were observed when Tu32 was crossed
to Estate.
The absence of recombinant types implies that
both parents have the same resistance gene as was
the
case with Cebada C a p a , La E s t a n z u e l a , G o n d a r , and Dabat
barley cultivars (P a r l e v l i e t , 1976).
closely
single
linked
locus.
loci
In
could
order
be
to
In addition,
involved
rather
distinguish
two
that
between
a
the
resistance factor(s) involved in this cross, screening of
the
F g progeny
virulent
would
be
necessary;
using
an
isolate
on either parent.
The merit of using isolates of different virulence
levels can be seen in the cross of Tu 17 x Cebada Capa.
The absence of susceptible plants in the Fg progeny, when
tested with the avirulent isolates,
suggests that Tu 17
and Cebada Capa have a gene in common, implying Pay, or
that
two
results
closely
of
virulent
the
linked
Fg
isolate
loci
progeny
showed
could
when
a
15:1
presence of two dominant genes.
be
involved.
inoculated
ratio
The
with
the
implying
the
The segregation ratio
obtained in the latter case could be due to either the
presence
C e bada
of
Capa,
another
or it
resistance
could
be
factor
due
to the
in
presence
virulence factor associated with Tu Ca 8 2 - I .
the
results
obtained
with
the
avirulent
Tu 17 or
in
of a
To clarify
and
virulent
79
isolates.
The virulence
considered
factor
in T u 0 a 8 2 - I should
be
in this interaction (Appendix, Table 23).
The rate at which the Pi hordei pathogen adapts to a
resistant
host
can
be
sources of resistance.
efficient,
it
reduced
by
using
For this diversification to be
should
be
controlled
virulence c o m p o s i t i o n of the pathogen.
thorough
monitoring
d i v e rsification
diversified
of
the
pathogen
of resistance
can
relative
to
the
This requires a
population.
The
be accom p l i s h e d
various strategies as discussed b e l o w , and hence,
by
will
increase the durability of resistance.
A combination of different resistances, even if they
are
each
controlled
by a s i n g l e
gene,
ma y
be
more
difficult for a pathogen to adapt to than a single gene
mechanism.
etc.)
A number of vertical genes (Pag,
available
Starling , 1 970;
in different barley
Clifford,
1974;
cultivars
Pag,
(Roane and
Parlevliet , 1 976)
confer adequate protection against Pi hordei.
Pay,
can
However, a
new race will need to change only one virulence gene to
overcome
host.
a single vertical gene
for resistance
To circumvent this risk, the use of multiple genes
in a c o m m o n background could be applied,
resistance in barley
this
in the
system,
two
or
cultivars
more
new
and a durable
could be realized.
and
still
In
effective
80
resistance genes could be placed into a new cultivar so
that
the pathogen
resistance genes
population has a barrier of several
presented
to it,
simultaneously.
This
should be an effective strategy, because, for a new race
to overcome the multiple resistance genes,
through
tw o
virulence,
or
thr e e
simultaneous
it must go
changes
toward
which is quite unlikely.
Multiple sources of resistance could be developed
using the adapted and resistant land race c u l t i v a r s in
combination with effective resistance genes,
and Pay.
For instance,
in the F g progeny
such as Pa^
of (Estate x
resistant land races) and (Cebada Capa x resistant land
races),
the resistant lines from each population could be
intercrossed.
Since
intercrossed
lines
the resistance
background
is
be
likely
to
of the
different,
a
considerable improvement could be expected.
The use of multilines is another strategy
often
overlooked
e n hancement
in
barley,
of durability
and
would
of resistance
that is
allow
the
to Pjt hordei.
The land race c u l t i v a r s analyzed are good candidates to
be used in such a strategy.
With the exception of Tu 17 ,
the other four land races were quite similar in maturity
and were adapted to dry land conditions.
Together,
they
could make an excellent mixture and could serve the same
81
purpose as a multiline.
The resistance genes in these
cultivars were probably different, but further testing is
needed to be conclusive.
Deploying single host genes over a wide agricultural
area in a monoculture can be potentially dangerous.
ideal
system
genes
over
would
time
or
be
in
to deploy
effective
restricted
An
resistance
geographic
areas.
Varieties with different resistance factors can be grown.
Then,
whenever their resistance breaks d o w n , t h e y
should
be removed and new varieties with different resistance
genes
should
different
to
be
introduced.
If
varieties
resistance genes are available,
recycle
them
after
they
hav e
production for a period of time.
been
resistance
have
it is possible
removed
fro m
This same system could
be applied in the deployment over space.
different
that
s o u r c e s ,could
different restricted geographic areas.
In this case',
be
planted
in
For this strategy
to be effective, an adequate and intensive disease survey
should be maintained.
The success of the strategies discussed above will
depend on the resistance genes involved.
For instance,
Pag was found to be temperature sensitive (Clifford and
Udeogalanya, 1976) and its effectiveness
in
semi-arid
climates
that
are
is questionable
characterized
by hot
82
weather.
Pay,
Pjl horde!
on the other hand, gave resistance to all
isolates
tested
studies (Parlevliet, 1976;
in
this
study
and
in other
Reinhold and Sharp, 1982);
as
yet there is no report of a b reakdown in resistance in
Pay .
It
is
of
resistance
programs.
major
genes
importance
before
they
to
test
are
used
the
in
worth
of
breeding
For a gene like Pay , a new race(s) that will
attack it could be created.
A virulent isolate such as
the Tu Oa 8 2 - 1 or the Sakka isolate (Reinhold and S h a r p ,
1976),
or any
other virulent
with a mutagen.
isolate
could
be treated
The mutant clones could be tested on the
resistant Pay gene.
A mutant that would attack this gene
would represent a new race.
Any plant genotype that is
resistant to this new race must have an unknown gene for
resistance in addition to the original resistance gene.
This
resistant
against
all
plant
races
in
must
the
have
field.
two
genes
The
effective
mutant
race
is
produced on the basis of known resistance genes, and in
that sense, the mutant is a future race.
The resistant
genotypes used in the field will select for races with
virulent genes that can overcome those resistance genes.
83
XI. SUMMARY AND CONCLUSIONS
Leaf
rust,
h o r d e l , presents
barley growers in Tunisia.
patterns, the
distribution
The variability
diversification
of virulence
that
effective
the
types
sources
barley
of
in
land
resistance
resistance genes identified
previously known
danger
to
in virulence
in pathogenicity, and the
different
regions in Tunisia have been shown.
indicate
a real
geographic
The genetic studies
race
to
cultivars
Pi
hordei.
have
The
were different from those
(except for the Tu32 resistance gene).
In summary, then, the following points can be made with
respect
to
the
epidemiology
of
hordei
and
the new
sources of resistance.
1.
Several virulence patterns of Pi, hordei
were
identified throughout the country of Tunisia.
2.
Most
of
the
Pi
hordei
isolates
were
site
specific, but several were found in more than
one geographic
3.
Using
region.
the virulence
formula
method
to compare
virulence patterns of the Pi hordei isolates,
new
virulences
were
identified
sites and in different years.
from
different
84
4.
New
virulent,
recombination
patterns
resulted
of Pj. h'ordei on
the
from
alternate
host, Ornithogalum spp„
5.
There
are
strong
indications
that
in
the
Northern and Northwestern parts of Tunisia, Pj
hordei completes it life cycle on Ornithogalum
spp.; whereas in the S o u t h , it o v e r s u m m e r s on
volunteer barleys in the Oasis.
6.
Pag
and
Pay
resistance
genes
were
effective
against all Tunisian Pj horde! isolates.
7.
The genetic analyses of crosses betw e e n land
race and
known
resistance
sources
of barley
c u l t i v a r s suggest t h a t , with the exception of
Tu 32,
the
resistance
cultivars
were
previously
identified.
- -
Tu I 6 was
genes
different
shown
resistance
to
gene
quantitative
manner
in
from
possess
these
barley
those
genes
a dominant
that interacted
in a
when
with
associated
Pa2+ ‘
- -
Tu 17, T u 27, and Tu 3 4 each have a dominant
resistance
8.
gene .
Cultivation of these
mixture is advocated.
land races in a multiline
85
9.
Additional genetic
studies should be conducted
to determine
relationships
the
betw e e n
the
resistance genes in the land race cultivars.
In conclusion,
to be effective, diverse gene pools should
be used in breeding programs.
provide
the
necessary
Not only do new gene pools
building
blocks
for
further
varietal improvement, but genetic diversity is essential,
if high levels of productivity are to be sustained.
varieties
with adequate resistance
New
could be developed
within a few years, if sufficient resources are provided
for this vital work.
86
REFERENCES' CITED
87
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1982.
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Pathogenic specialization in
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\
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Knot,
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Alien g e r m p l a s m as a
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L i n e , R. F ., E. L. Sharp and R. L. Powelson.
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1979.
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Barley diseases and their control,
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A
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The g e n e t i c s of s e e d l i n g
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1977.
Plant pathosystems: an attempt
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Parlevliet, J. E . 1979. -C o m p o n e n t s of resistance that
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Partial
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Relationship between field trials, micro-plot
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90
Parlevliet,
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Presence in Morocco of
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Sources of
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Interspecific and intergeneric
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Taxonomy, botany,
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Genes for resistance among
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Inheritance of
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Evidence for two populations of
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Control of barley diseases 'in
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Control of barley diseases in lesser
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93
APPENDIX
Table 20.
Initial studies of physiologic specialization
in the cereal rust diseases caused by Puccinia
spp .1
____ Mrrbfirof
tost
Ehthqapi
Ihte
tost
Ehthqgen (Etoiima)
differentials races publ±±ed
MhoKs)
____________ Sbeeies ___________________________ __________
Ifiticun s d d .
Tfitdam sro.
Avaia spp.
Avaia sp p .
Tfitiom a®.
fecalis
Hirtom
Zea
Tfitiom
tocalis
ararainis f. so. tritdci
erarainis f. so. tritici
ocrasta f. so. averse
erarmnis f. ai. aven^
reccndita f. s o . tritici
reccndita f.so. secalis
kardei
scarp^ii
striifcnms
eranrinis f. so. secalis
I fbcrn Ibelfb (1984).
-
1917
12
-
1922
2
4
1919
3
5
-
I
2
1923
1926
1926
2
2
1926
3
6
4
1926
4
1930
5
3
.1 9 3 2
7
.
12
Staknm and Edancival
Stakman and Levine
toemer
Stakman et al.
Efeins and Jadooi
Efeins
Efeins
Efeins
Alliscn and lsedieck
Cottm and Levine
95
Table 21.
Description
of
infection
types
used
physiologic
specialization
studies
of
cereal rusts^
in
the
Disease
Host Response
(Class)
Infection
Type
Symptoms
Immune (Res)
O
low
no
uredia
or
other
macroscopic sign of infection
Nearly
Immune (Res)
0; low
no uredia, but hypersensitive
necrotic or chlorotic
flecks
of varying size present •
Very
Resistant (Res)
I
low
small
uredia
necrosis
Moderately
Resistant (I)
2
low
small to medium uredia, often
surrounded
by chlorosis
or
necrosis, green island may be
surrounded
by chlorotic
or
necrotic border
surrounded by
Moderately
3
Susceptible (S)
medium
sized uredia that may
be 'associated with
chlorosis
or rarely necrosis
Susceptible (S) 4
high amount
uredia
chlorosis or necrosis
1
Roelfs and McVey (1979); Stakman et a l . (1962).
without
96
Table 22.
Isolate
BEIA
TUBj82-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
-VlI
TuBj84-1
-2
-3
-4
-5
-6
-7
-8
Virulence patterns of Puccinia hordei isolates
sampled in Tunisia in 1982, 1983 and 1984.
____________
Differential Host Genotypes _________ ____
1 2
3 4
5
6
7
8
9
10 11 12 13
Esta C.Ca Hor Rica Bolivia Quinn Magn Peru Suda Rgyp Batn Gold Reka
Pag Pa^ Pag Pa2+ Pa2+Pag Pk2H-Pa5 Pa5 Pa2 Pa Pag Pa2+ Pa^ Pa2+
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R .
R
R
R
R
R
RR
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
I
S
I
I
R
R
S
S
R
I
R
S
S
S
I
R
R
R
R
S
S
I
S
R
R
R
R
R
R
I
S
S
R
R
R
S
S
S
S
S
S
S
R
R
S
R
S
S
S
S
S
S
S
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
S
R
I
R
S
R
R
R
S
R
S
R
R
R
R
R
R
S
S
I
S
I
S
S
R
S
R
R
R
S
S
S
S
S
S
S
S
S
S
S
S
S
R
I
S
I
S
S
I
I
S
■S
S
S
S
S
S
S
S
S
S
I
S
S
R
S
S
S
S
S
S
S
S
S
I
I
S
S
S
S
S
S
I
S
S
R
S
S
S
S
S
S
R
S S
S
S R
S S
S S
S S
R
S S
S R
S
S S
R S
S S
S S
S S
S S
S S
S
S S
R
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S
R
S
I
S
S
I
R
S
S
S
S
S
S
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
KEF
TuKe82-1
-2
-3
-4
-5
-6.
-7
-8
-9
-10
TuKe84-1.
-2
-3
S
R
S
R
R
S
S
S
S
S
S
S
S
T Resistance genes: R = resistant (effective), I - intermediate (effective),
S = susceptible (ineffective).
97
Table 22.
Isolate
(Continued)
Differential Host Genotypes
8
10 11 12 13
4
6
I
2
7
9
5
3
Esta C.Ca Hor Rica Bolivia Quinn IvUgn Peru Suda Ejgyp Batn Gold Reka
PSg Pcly Pag Rag+ Pclg+Bclg Pclg+Pcl^ R=If) Pag Ra Pa8 Ra2+ Pai, Pa2+
MATEOR
TUMa82-1
TUMaSB-I
-2
-3
-4
-5
-6
-7
-8
-9
-10
-11
-12
-13
-14
-15
-16
TUMaSM
-2
-3
-4
-5
-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
R
R
R
R
R
S
R
I
S
I
s •
I
S
R
S
R
I
S
S
I
S
S
R
R
R
R
I
I
R
R
I
S
I
S
S
S
R
I
R
S
S
I
R
I
R
S
S
R
R
R
I
S
S
R
S
I
S
S
S '
R
S
S
S
S
R
S
S
S
S
S
S
S
S
I
S
I
S
S
S
S
S
S
R
S
I
R
R
R
R
R
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
R
S
S
R
R
R
R
R
S
S
S
S
S
S
I
S
I
S
S
S
S
S
S
R
S
S
S
S
S
I
S
S
S
S
S
S
S
S
R
S
S
R
S
I
S
S
I
I
S
S
S
S
S
S
S
R
R
S. S
S
S
R
S
R
S
R
S
S 'S
R
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
I
I
S
S
S
S
S
R
S
S
S
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S.
S
R
S
S
R
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
R
I
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
OASIS
TuQa82-1
-2
-3
-4
-5
-6
-7
-8
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
S
I
I
R
R
R
S
I
S
S
I
S
S
R
I
R
S
S
I
S
S
R
S
I
S
S
R
I
S
S
R
I
S
S
S
I
S
S
S
S
S
S
S
R
S
S
I
S
S
S
I
S
S
S
I
S
S
S
S
S
S
R
S
S
S
S
R
I
S
R
S
I
S
S
S
R
S
S
S
S
S
S
S
S
S
S
S
S
1 Resistance genes: R = resistant (effective), I = intermediate (effective),
S = susceptible (ineffective).
98
Table 22.
(continued)
______________ Differential Host Genotypes________________
1 2
3 4
5
6
7
8
9
10 11 12 13
Isolate
Esta C.Ca Hor Rica Bolivia Quinn Mhgn Peru Suda Bgyp Batn Gold Reka
Pa3 fey Pag Pa2+ Eh^+F&tS 1^E+paS
^
Pag Ea2+ Pa^ Pa2+
EL JEM
I
S
S
S
S
S
S
S
I
S
I
S
S
S
I
S
S
S
S
S
R
S
S
S
R
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S'
S
I
S
S
I
SS
S
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
I
S
S
I
S
S
S
S
S
S
S
S
S
S
S
S • S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
TbEj83-1
R
R
R
R
R
R
MARETH
Mfe83-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
S
I
R
S
S
I
R
R
I
R
S
R
S
S
S
R
R
R
S
S
S
S
S
S
S
S
R
BOORBIA
TUBr82-1
-2
R
R
R
R
R
R
R
R
R
I
KAIROUAN
TuKa82-1
-2
R
R
R
R
I
R
R
R
S
S
S
S
S
S
S
S
S
1 Resistance genes: R = resistant (effective), I = intemsdiate (effective),
S = susceptible (ineffective).
.99
Table 23.
Host Genotypes
Possible
genotypes
involved
in
the
interaction
between
(Tu 17 x Cebada
Capa)
progeny and (TuKe82-5 , Tu0a82- I) Pjl hordei
isolates.
Genotype of P. hordei isolates and interactions
Tu0a82-1
Int2
Int2
TuKe82-5
AAbbCC (Tu 17)
aaBBCC (Cebada Capa)
AaBbCC (F1)
AABBCC'
AABBCC
AABBCC
gene frequency F2 progeny
AABBCC
I AABBCC
AABBCC ■
2 AABbCC
AABBCC
I AAbbCC
AABBCC
2 AaBBCC
AABBCC
4 AaBbCC
AABBCC
2 AabbCC
AABBCC
I aaBBCC
AABBCC
2 aaBbCC
AABBCC
I aabbCC
F2 segregation ratio
R
R
R
AABBcc
AABBcc
AABBcc
R
R
R
R
R
R
R
R
R
R
R
R
AABBcc
AABBcc
AABBcc
AABBcc
AABBcc
AABBcc
AABBcc
AABBcc
AABBcc
R
R
R
R
R
R
R
R
S
no seg.
I
15:1
1 Both isolates TuKe82-5 (AABBCC) and Tu0a82-1 (AABBcc) are avirulent
on Cebada Capa (aaBBCC) and Tu17 (AAbbCC). The two cultivars have
«CC' in common.
F2 progeny gave some susceptible plants when
inoculated with TuOa82-1 and none with TuKe82-5 because of the
'cc'virulence gene in Tu0a82-5.
2
Int = interaction
Table
24 . Possible gen o t y p e s involved in the, interaction
b e t w e e n (Tu I 6 x R e k a I ) p r o g e n y and ( T u 0 a 8 2 - 5 )
P. horded, isolate.
Host Genotypes
Genotype of P. hordei isolate and interaction
. Interaction
Tu0a82-1
AAbbcc (Tu 16)
aaBBcc (Rekal)
AaBbcc (F1)
AABBcc
AABBcc
AABBcc
gene frequency FP progeny
AABBcc
I AABBcc
AABBcc
2 AABbcc
AABBcc
I AAbbcc
AABBoc
2 AaBBcc
AABBcc
4 AaBbcc
AABBcc
2 Aabbcc
AABBcc
I aaBBcc
AABBcc
2 aaBbcc
AABBcc
I aabbcc
F2 segregation ratio
i
S
S
S
'
R
R
S
R
S
S
■S
. S
S
5:11 (1:3)
1 BB (host) in combination with BB (pathogen) = not effective,
i.e. susceptible reaction. AA (host) in combination with AA
(pathogen) = not effective, i.e. susceptible reaction. Two
dominant alleles at one locus and at least one dominant allele
at another locus are required to counter the virulence of
'cc*, and the avirulence of 'AA1 and 1BB1 genes of the
pathogen in a quantitative manner.
Resistant types can result from (susceptible x susceptible)
depending on virulence genes present in the pathogen. All
plants in (Tul6 x Rekal) would be susceptible if Tu0a82-1 has
two virulence genes, i.e. lAAbbcc
101
A.
T
Li Gilite
Menzel
B izerte
Tunis-Cirthige
>na/
Cape Bon
Kerkouane
THIRTY CENTURIES AGO
I Phoenicians were the first to
1 establish colonies on the coast of
a land inhabited by a people who
would later be called Berbers.
Among those outposts Carthage
grew to a rich and powerful citystate that traded with, then
threatened, Rome.
"Delenda esl Carthago— Carthage
must be destroyed,” was the
unflinching aim of the Roman
statesman Cato.
And, despite the
brilliant victories
of Hannibal, it
was destroyed in
146 B .c . Utterly.
The conquering Romans built and
rebuilt and improved the water
supply with aqueducts, one of
which is still in use.
In time and in turn others came
to control the land: Vandals,
Byzantines, Arabs, Turks, and
French. Not until 1957 was the
Republic of Tunisia proclaimed
under the leadership of Habib
Bourguiba, who has since been
made president for life. With
traditions from both the Islamic
and European worlds,
g
Tunisia has followed
a
a nonaligned foreign
policy friendly to the
West, while concentrating
on social and economic
development. As with
other developing countries,
population has grown faster than
jobs; many Tunisians work abroad,
primarily in France and Libya.
AREA: 164,200 sq km (63.400 sq mi).
POPULATION: 6,000,000.
LANGUAGES: Arabic, French.
RELIGION: 98% Muslim. ECONOMY:
M
_■«-,I IAgriculture
\t 4__ ImwidesbltorOtSERTI
E'. Kuin
lyuinti
I I-OUVES
fHftkluidpiptlii*
rIffrU vtd piptlim
lVVlnmiT
Pr * ■
ArotiMits
ORARES
I,
f
T B orj
El K h a d ra
\
Figure
15.
Agriculture, tourism, textiles,
phosphate, fishing, modest petroleum
reserves and processing. MAJOR CITY:
Tunis, capital, pop. 1,000,000.
CLIMATE: Temperate in the north; hot,
almost wholly arid desert in the south.
,■>a wsT
) ■I -Iesrartograss
I
Map o f T u n i s i a
AOUtDUCTS
.^
(from N a t i o n a l
G e o g r a p h i c , Feb.1980)
I
MONTANA STATE UNIVERSITY LIBRARIES