Chromosome segregation in a Triticum aestivum L. em. Thell. by T. durum Desf. cross and the
production of D genome addition lines
by Leonard Robert Joppa
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY in GENETICS
Montana State University
© Copyright by Leonard Robert Joppa (1967)
Abstract:
Seven lines of Chinese Spring, each tetrasomic for one of the chromosomes in the D genome, were
crossed to the durum varieties Wells and Lakota. The F1 from these crosses possessed 15 pairs plus 6
univalent chromosomes at metaphase I of meiosis. Chromosome combinations in the F2 were
determined cytologically and those plants with combinations approaching 15 pairs were selected for
advancement to the F3.
Eight plants with 15 pairs of chromosomes (D diplosomic, i.e. 14 pairs from the A and B genomes plus
one pair from the D genome) were obtained in the F3. Of these eight plants, five proved to be male
sterile and three were partially fertile. Two of the fertile plants were presumed to be 4D diplosomics
and the third was probably a 5D diplosomic. All F4 progeny of these three plants had 15 chromosome
pairs.
Plants with 15 pairs of chromosomes occurred most frequently in the progeny of F2 plants having 15
pairs plus one to four univalents. These plants were generally lacking in vigor and either partially or
completely sterile. Neither the two durums or the seven tetrasomic hexaploids used as parents affected
the chromosome segregation in their F2 progenies.
In another part of the study, the frequencies of plants with various chromosome combinations in the F2
of crosses between the hexaploid spring wheat variety Thatcher and the durum varieties Wells, Lakota
and Langdon, were determined. As expected the F1 plants had the chromosome combination 14 pairs
plus 7 univalents. Plants with 14 pairs plus zero to seven univalents were observed most frequently in
the F2. A number of plants with 15 pairs plus one to four univalents were also observed. The particular
durum variety used in the crosses did not affect the frequencies of various chromosome combinations
in F2,plants.
The hexaploid spring wheat Ceres was crossed to Wells durum and the F1 was then backcrossed to
Wells. The number of univalents present in plants from this cross was used as a measure of the
frequencies with which various numbers of univalents were passed through female and male gametes.
These frequencies were used to predict the number of chromosomes expected in Fg plants of the
Thatcher X durum crosses. Three of the seven possible classes deviated significantly from the expected
frequencies.
If the assumption is made that each of the seven univalent chromosomes in F1 plants has an equal
chance of being included in a particular gamete, then the frequencies with which the same univalent is
obtained from both female and male gametes can be calculated. This assumption was used to calculate
the expected frequencies of various chromosome combinations in F2 plants of the Thatcher X durum
crosses. A comparison of the observed frequencies with the calculated frequencies indicated that three
classes (formula not captured in OCR) deviated significantly from the expected. The total chi square
value of 49.1 has a probability of 0.25 with 35 degrees of freedom. / 7/
CHROMOSOWE SEGREGATION IN A IR ITICUM AESTIVUM L . E M . THELL.
BY T . DURUM EESF. CROSS AND THE PRODUCTION OF D GENOME ADDITION LINES
by '
LEONARD ROBERT JOPPA
A t h e s i s s u b m i t t e d to t h e G r a d u a t e F a c u l t y in p a r t i a l
f u l f i l l m e n t o f t h e r e q u i r e m e n t s f o r th e d e g r e e
of
DOCTOR OF PHILOSOPHY
in
GENETICS
Approved:
* P 1%)
_
Chairman. Major Department
Chairman, E^amini^g Committee
Dean
lduate D ivisi
MONTANA STATE UNIVERSITY
Bozeman, Montana
December, 1967
/
- iii
ACKNOWLEDGMENT
The a u t h o r would l i k e t o e x p r e s s h i s d e e p e s t a p p r e c i a t i o n t o D r „ F„ H
McNeal f o r h i s h e l p and g u id a n ce d u r i n g t h e co u rs e o f t h i s i n v e s t i g a t i o n 0
He would a l s o l i k e to e x p r e s s h i s a p p r e c i a t i o n t o th e s t a f f o f the
P l a n t and S o i l S c ie n c e Department f o r t h e i r h e l p and encouragement and to
Montana S t a t e U n i v e r s i t y f o r f i n a n c i a l a s s i s t a n c e as w e l l as use o f f a ­
cilities
o
A s p e c i a l n o t e o f t h a n k s i s due D r 0 E 0 R0 S ea r s o f t h e Crops Research
D i v i s i o n , A g r i c u l t u r a l Resea rc h S e r v i c e a t t h e U n i v e r s i t y o f M i s s o u r i ,
Columbia, M i s s o u r i , f o r s u g g e s t i n g t h e use o f te t r a s ' o m i c s and f o r s u p p l y ­
ing c e r t a i n a n e u p l o i d s used i n t h i s s t u d y .
. - iv TABLE OF CONTENTS
Page
V I T A ................................................................. ' ........................ ....................................
„
ACKNOWLEDGMENT
ii
iii
TABLE OF CONTENTS...........................................................................................................
iv
LIST OF TABLES .....................................................................
v
LIST OF FIGURES..................................................................
vii
ABSTRACT . . ..............................................................................
v iii
INTRODUCTION . . ■............................................................................................
I
REVIEW OF LITERATURE.......................
3
MATERIALS AND METHODS. . . . .....................................................................
E xp er im en t
12
I ......................................................................
.
E xp er im en t TI .......................................................................................
13
RESULTS...................................................
E xp er im en t
15
I . ..................................................
E x p er i m en t I I
. .
15
. . . . . . . . . . . . . . .
29
DISCUSSION ........................ . . . . . . . . . . . . . . . . . . . . .
Experiment
52
I ..............................................
E x p er i m en t I I
. .......................
52
. . . . . . . . . . . . . . . .
55
SUMMARY...........................
59
APPENDIX ................................................................
Ta bl e
12
.
I . . . . . . . . . . . . . . . . . . . . . . . . . .
Tabl e I I ............................................................
LITERATURE CITED. ............................ .... ........................................................... ....
62
63
64
. .
68
V
LIST OF TABLES
Page
Tabl e
Tabl e
T ab l e
Ta b l e
Tabl e
Ta bl e
T ab l e
Ta bl e
Ta bl e
Tabl e
T ab l e
I. .
II.
III.
IV.
V.
VI.
VII.
V III.
IX.
X.
XI.
The gr ou ps o f v a r i e t i e s ( c u l t i v a r s ) o f th e genus
T r i t i c u m . A f t e r Mor ris and S ear s (1967) . . . . . .
4
Observed f r e q u e n c i e s o f chromosome c o m b in at io n s in
Fp pr oge ny o f t h r e e s p r i n g wheat X durum c r o s s e s . .
16
Chromosome numbers in BC]_ pr og eny o f a (Ceres X
W e l ls ) X Wells c r o s s ............................................................
. .
20
Numbers o f chromosomes o b s e r v e d i n Fp p l a n t s
compared t o e x p e c t e d number based on number o f '
u n i v a l e n t s p a s s e d t h r o u g h female gametes in BC^
pr o ge n y o f a (Ceres X W el ls ) X Wells c r o s s , and
random zyg ot e f o r m a t i o n .................................................................
21
F r e q u e n c i e s o f chromosome co m b in at io n s o b s e r v e d in
t h e Fp p r o g e n i e s o f T h a t c h e r X durum c r o s s e s as
compared t o t h e f r e q u e n c i e s e x p e c t e d , based on
u n i v a l e n t s p a s s e d t h r o u g h female gametes i n a
(Ceres X Wel ls) X Wells c r o s s ...................................................
24
Fr equ enc y o f is o s o m ic s and t e l o s o m i c s i n t h e Fp
p r o g e n i e s o f s p r i n g wheat X durum c r o s s e s . . . . . .
26
M u ltiv a le n ts observed in progenies of hexaploid
by t e t r a p l o i d wheat c r o s s e s . ...................................................
28
F r e q u e n c i e s o f p l a n t s w i t h v a r i o u s chromosome
co m b in a ti o n s in th e Fp o f c r o s s e s o f t h e t e t r a s o m i c h e x a p l o i d Chine se S p rin g X durum . . . . . .
i . . .
31
A d d i t i o n a l chromosome co m b in at i o n s o b s er v ed i n F^
p l a n t s o f t e t r a s o m i c Chine se S p r in g X durum c r o s s e s .
32
F r e q u e n c i e s o f v a r i o u s chromosome co m b in at io n s i n th e
Fp p r o g e n i e s o f T h a t c h e r X durum and t e t r a s o m i c
C h in e se S p r in g X durum c r o s s e s ...............................................
36
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s
w i t h v a r i o u s chromosome co m b in at io n s in t h e progeny
o f Fp p l a n t 2-13 from t h e c r o s s t e t r a s o m i c ID X Wells
with Ipix + 4I
39
- vi
Page
Table
Tabl e
T ab l e
Tabl e
Table
Tabl e
Tabl e
Table
XII.
X III.
XIV.
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f
p l a n t s w i t h v a r i o u s chromosome co m b in at io n s i n
t h e pr og en y o f Fg p l a n t 29-3 from th e c r o s s
t e t r a s o m i c 5D X Wells w i t h 1 5 j j Ty4 j . . . . . . .
.
40
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f
p l a n t s w i t h v a r i o u s chromosome co m bin ati on s i n t h e
pr o ge n y o f Fg p l a n t 17-2 from th e cross t e t r a s o m i c
4D X Lakot a w i t h I b j j + 5 j ..................................... ....
41
V i g o r , f e r t i l i t y gnd o t h e r c h a r a c t e r i s t i c s o f p l a n t s
w i t h v a r i o u s chromosome c o m b in at io n s i n t h e progeny
o f Fg p l a n t 33-9 from t h e c r o s s t e t r a s o m i c 6D X
durum w i t h 15 j j + b j .....................................
45
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s
w i t h v a r i o u s chromosome c o m b in at io n s i n t h e progeny
o f Fg p l a n t 31-4 from t h e c r o s s t e t r a s o m i c 6D X
durum w i t h 15 j j + 4 j ................................................................. '
45
F requency o f chromosome co m b in at io n s in two Fg
f a m i l i e s from t h e c r o s s t e t r a s o m i c 3D X W e l l s . . .
46
XVII. V ig o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f
p l a n t s w i t h v a r i o u s chromosome comb ina ti on s i n th e
pr ogeny o f Fg p l a n t 9-11 from t h e c r o s s t e t r a s o m i c
2D X Wells w i t h 15%% + 5%........................................................
48
XV.
XVI.
XVIII.
XIX.
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f
p l a n t s w i t h v a r i o u s chromosome co m bin ati on s i n th e
pr og eny o f Fg p l a n t 13-10 from th e c r o s s t e t r a s o m i c
3D X Dakota w i t h 15%% + 4% + I t e l o .................................
49
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s
w i t h v a r i o u s chromosome co m b in at i o n s in th e progeny
o f Fg p l a n t 35-17 from t h e c r o s s t e t r a s o m i c 7D X
Dakota w i t h 15%% + 5%.................................................................
50
7-
)
vi a
APPENDIX
Ta bl e . I .
Ta bl e I I .
Page
F r e q u e n c i e s w i t h which gametes w i t h v a r i o u s numbers
of. chromosomes a r e e x p e c t e d t o form z y g o t e s , based
on th e f r e q u e n c y w i t h which female gametes p a s s e d
u n i v a l e n t s i n a c r o s s , (Ceres X W el ls} X Wells . . . .
63
P o s s i b l e chromosome c o m b i n a t i o n s , t h e gametes from
which t h e y cou ld be formed, p r o b a b i l i t y o f th e zygote
b e i n g o b t a i n e d and f r e q u e n c y w i t h which u n i v a l e n t s
i n d i f f e r e n t gametes a r e a l i k e i n F2 p l a n t s o f ■
T h a t c h e r X durum c r o s s e s . Based on Appendix Tabl e I
and d i f f e r e n c e s i n t h e f r e q u e n c y w it h which d i f f e r ­
e n t chromosomes were i n c l u d e d i n gametes ............................
64
- vii LIST OF FIGURES
Page
Figure I .
Anaphase I o f m e i o s i s i n T h a t c h e r X durum c r o s s e s
Figure 2.
T r i v a l e n t s a t metaphase I o f m e i o s i s i n t h e Fg o f
T h a t c h e r X durum c r o s s e s ..................................... ....
F i g u r e 3.
. . .
17
27
D i a k i n e s i s t o metaphase I o f m e i o s i s in Fg p l a n t s
from t e t r a s o m i c Chine se S p r in g X durum c r o s s e s
w i t h chromosome co m b in at i o n s ap p ro ac hin g 1 5 j j . . .
30
Figure 4 .
F3 p l a n t s 1 7 -2 -6 and 1 7 -2 -1 0 w i t h 15 j j o f chromosomes .
42
F i g u r e 5.
Metaphase I o f m e i o s i s and anap ha se I o f m e i o s i s i n F^
p l a n t 1 7 - 2 - 1 0 - 4 .......................................................................... . .
43
ABSTRACT
Seven l i n e s o f Ch in es e S p r i n g , ea ch t e t r a s o m i c f o r one o f th e c h r o ­
mosomes in t h e D genome, were c r o s s e d t o t h e durum v a r i e t i e s Wells and
L a k o t a . The Fj_ from t h e s e c r o s s e s p o s s e s s e d 15 p a i r s p l u s 6 u n i v a l e n t
chromosomes a t met a phase I o f m e i o s i s . Chromosome co m b in a ti o n s i n th e Fp
were d e t e r m in e d c y t o l o g i c a l l y and t h o s e p l a n t s w ith c o m b in at io n s ap p r o a c h ­
ing 15 p a i r s were s e l e c t e d f o r advancement to t h e Fg. ('
E i g h t p l a n t s w i t h 15 p a i r s o f chromosomes (D d i p l o s o m i c , i . e . 1.4'pairsfrom t h e A and B genomes p lu s one p a i r from t h e D genome) were o b t a i n e d in
t h e Fg . Of t h e s e e i g h t p l a n t s , f i v e proved t o be male s t e r i l e and t h r e e
were p a r t i a l l y f e r t i l e .
Two o f t h e f e r t i l e p l a n t s were presumed to be
4D d i p l o s o m i c s and t h e t h i r d was p r o b a b l y a 5D d i p l o s o m i c . A ll F^ progeny
o f t h e s e t h r e e p l a n t s had 15 chromosome p a i r s .
P l a n t s w i t h 15 p a i r s o f chromosomes o c c u r r e d most f r e q u e n t l y i n th e
pr o ge ny o f Fg p l a n t s hav in g 15 p a i r s plus' one t o f o u r u n i v a l e n t s . These
p l a n t s were g e n e r a l l y l a c k i n g in v i g o r and e i t h e r p a r t i a l l y o r co m p le te ly
sterile.
N e i t h e r t h e two durums o r t h e se v e n t e t r a s o m i c h e x a p l o i d s used
as p a r e n t s a f f e c t e d t h e chromosome s e g r e g a t i o n i n t h e i r Fg p r o g e n i e s .
In a n o t h e r p a r t o f t h e s t u d y , t h e f r e q u e n c i e s o f p l a n t s w i t h v a r i o u s
chromosome co m b in at i o n s i n t h e Fg o f c r o s s e s between t h e h e x a p l o i d s p r i n g
wheat v a r i e t y T h a t c h e r and t h e durum v a r i e t i e s W el ls , La kot a and Langdon,
were d e t e r m i n e d . As e x p e c t e d t h e F^ p l a n t s had th e chromosome com bina tion
14 p a i r s p l u s 7 u n i v a l e n t s . P l a n t s w i t h 14 p a i r s p lu s ze ro t o seven
u n i v a l e n t s were o b s e r v e d most f r e q u e n t l y i n t h e Fg. A number o f p l a n t s
w i t h 15 p a i r s p l u s one t o f o u r u n i v a l e n t s were a l s o o b s e r v e d . The p a r ­
t i c u l a r durum v a r i e t y used i n t h e c r o s s e s d i d n o t a f f e c t t h e f r e q u e n c i e s
o f v a r i o u s chromosome c o m bi n at io ns i n F g , p l a n t s .
The h e x a p l o i d s p r i n g wheat Ceres was c r o s s e d t o Wells durum and th e
Fj was t h e n b a c k c r o s s e d to W e l l s . The number o f u n i v a l e n t s p r e s e n t in
p l a n t s from t h i s c r o s s was used as a measure o f the f r e q u e n c i e s w it h which
v a r i o u s numbers o f u n i v a l e n t s were p a s s e d t h r o u g h female and male gametes.
These f r e q u e n c i e s were used t o p r e d i c t th e number o f chromosomes ex p ec te d
in Fg p l a n t s o f t h e T h a t c h e r X durum c r o s s e s . Three o f t h e se v en p o s s i b l e
c l a s s e s d e v i a t e d s i g n i f i c a n t l y from th e e x p e c t e d f r e q u e n c i e s .
I f th e a s s u m p ti o n i s made t h a t e ac h o f th e seven u n i v a l e n t chromo­
somes i n Fj p l a n t s has an eq u a l chance o f b ei n g i n c l u d e d i n a p a r t i c u l a r
g am et e, t h e n t h e f r e q u e n c i e s w it h which t h e same u n i v a l e n t i s o b t a i n e d
from b o th female and male gametes can be c a l c u l a t e d . This ass um p ti o n was
used t o c a l c u l a t e t h e e x p e c t e d f r e q u e n c i e s o f v a r i o u s chromosome combi­
n a t i o n s i n Fp p l a n t s o f t h e T h a t c h e r X durum c r o s s e s . A comparison o f th e
observed freq u en cies with the c a l c u la te d frequencies in d ic a te d t h a t three
c l a s s e s ( 1 6 j j + 3 j , 15j j + I j and 14 j j ) d e v i a t e d s i g n i f i c a n t l y from th e
e x p e c t e d . The t o t a l c h i s q u a r e v al u e o f 4 9 . 1 has a p r o b a b i l i t y o f 0.2 5
w i t h 35 d e g r e e s o f freedom.
INTRODUCTION
S p e c i e s o f t h e genus T r i t i c u m can be d i v i d e d i n t o t h r e e groups based
on chromosome number.
The groups and t h e i r chromosome numbers a r e :
( l ) d i p l o i d , seven p a i r s ; (2) t e t r a p l o i d ,
14 p a i r s ; (3) h e x a p l o i d , 21
pairs.
T h e h e x a p l o i d s a r e t h e o n l y gr ou p w i d e l y grown i n t h e United
S tates.
They a r e d i v i d e d i n t o t h e s p r i n g wheats and w i n t e r w h ea ts .
T e t r a p l o i d wheats a r e grown to some e x t e n t th r o u g h o u t t h e world bu t durum
wheats a r e th e o n l y r e p r e s e n t a t i v e o f t h i s group commonly grown i n the
U ni te d S t a t e s .
D i p l o i d s p e c i e s a r e seldom grown co m m e r c i a ll y .
H e x ap lo id and t e t r a p l o i d wheats have been c r o s s e d f r e q u e n t l y .
The
p u r p o s e o f s u c h c r o s s e s has u s u a l l y been t o t r a n s f e r d i s e a s e r e s i s t a n c e o r
some o t h e r c h a r a c t e r i s t i c from one s p e c i e s t o th e o t h e r .
r e s u l t d e s i r e d was improvement o f t h e h e x a p l o i d .
U s u a l l y th e end
F r e q u e n t l y one o r more
b a c k c r o s s e s were made t o t h e h e x a p l o i d p a r e n t t o f a c i l i t a t e r e t u r n t o a
f u l l h e x a p l o i d chromosome complement.
S t u d i e s of chromosome p a i r i n g and
chromosome s e g r e g a t i o n have seldom i n c l u d e d t h a t p o r t i o n o f t h e p o p u l a ­
t i o n which ap pr oac hed 14 p a i r s .
Aneuploids, ( i . e .
chromosome numbers o t h e r th a n a s im p l e m u l t i p l e o f
t h e b a s i c chromosome number) have been w i d e l y used i n g e n e t i c s t u d i e s .
Monosomies ( 2 n - l ) and n u l l i s o m i c s
( 2 n - l p a i r ) have been used t o l o c a t e
genes on chromosomes, t o s u b s t i t u t e a chromosome p a i r from one v a r i e t y
i n t o a n o t h e r and t o i d e n t i f y genome h o m o l o g ie s .
tetrasom ics
T r i s o m ic s
(2n + I) and
(2 n + I p a i r ) have been used t o s t u d y dosage e f f e c t s and to
l o c a t e genes on p a r t i c u l a r chromosomes as w e l l as f o r o t h e r s t u d i e s .
T r i s o m i c s and t e t r a s o m i c s have been s t u d i e d a t t h e h e x a p l o i d l e v e l in
wheat b u t n o t a t t h e t e t r a p l o i d l e v e l .
Matsumura ( 1952b) produced a
)
)
■ ) ___________________________________________________________________________________________
-
2
—
number o f ha pl o so m ic s (14 p a i r s from t h e A and t h e B genomes p l u s I
chromosome from t h e D genom e)„
He a l s o found a d i p l o s o m i c (14 p a i r s from
t h e A and t h e B genomes p l u s I p a i r from t h e D genome)„
were u n s t a b l e and q u i c k l y r e v e r t e d t o 14 p a i r s „
The haplosomics
The d i p l o s o m i c was more
s t a b l e , b u t low i n f e r t i l i t y .
,
>
The use o f monosomies, n u l l i s o m i c s and s u b s t i t u t i o n l i n e s has i n d i ­
c a t e d th e im po rta nc e o f t h e D genome chromosomes.
S e v e r a l s t u d i e s have
shown t h a t f l o u r q u a l i t y and o t h e r c h a r a c t e r i s t i c s a r e i n f l u e n c e d by t h e s e
chromosomeso
These s t u d i e s
(K us pi r a and Unrau, 1957; M o rr is e t a l . , 1966)
have i n d i c a t e d t h a t m o r e ■t h a n one o f t h e D genome chromosomes a r e cap ab le
of a f f e c t i n g q u a l i t y .
For ex am p le , chromosomes 4B, 7B and 5D a f f e c t
s t r o n g dough and 4D, 7D and 5D a f f e c t l o a f volume, c r u s t a p p e a r a n c e , and
g r a i n and t e x t u r e o f t h e l o a f .
to a f f e c t p ro te in c o n te n t.
Chromosomes 3D, 4D, SB and 7B a r e r e p o r t e d
Welsh and Hehn (1964) r e p o r t e d t h a t chromosome
ID a f f e c t e d g l u t e n s t r e n g t h when i n t h e monosomic c o n d i t i o n .
I n view o f t h e s e f i n d i n g s i t would be o f c o n s i d e r a b l e i n t e r e s t to
d e t e r m i n e th e e f f e c t o f s i n g l e p a i r s o f D genome chromosomes on f l o u r
q u a l i t y , and on o t h e r c h a r a c t e r i s t i c s c a r r i e d by D genome chromosomes.
If
t h e complete s e t o f D genome d ip l o s o m i c s cou ld be i s o l a t e d , t h e c h a r a c ­
t e r i s t i c s which d i s t i n g u i s h t h e t e t r a p l o i d wheats from h e x a p l o i d wheats
c o u l d be s t u d i e d chromosome by chromosome.
The pur pos e o f t h i s s t u d y was t o d e t e r m i n e chromosome s e g r e g a t i o n in
c r o s s e s o f t e t r a p l o i d T r i t i c u m durum D e s f . X T r i t i c u m a e s t i v u m L. em
T h e ! ! , and t o i s o l a t e l i n e s w i t h t h e se v e n p o s s i b l e D d i p l o s o m i c s .
REVIEW OF LITERATURE
Cvto-taxonomv and O r i g i n o f Common Wheat:
The genus T r i t i c u m was one o f t h e f i r s t o f t h e p l a n t g e n e r a to be
investigated c y to lo g ic a lly .
Sakamura (1918) r e p o r t e d t h a t t h e group con­
s i s t e d o f t h r e e p l o i d y l e v e l s w it h chromosome numbers o f 14, 28, and 42.
Sax (1923) and H. K ih ar a (1919, 1924) d e m o n s t r a t e d th e a l l o p o l y p l o i d
n a t u r e o f t h e 28 and 42 chromosome grou ps by means o f i n t e r s p e c i f i c
crosses.
K ih ar a (1929, 1930) dev el op ed h i s genome a n a l y z e r method based
upon t h e r e s u l t s o f i n t e r s p e c i f i c c r o s s e s between t h e t e t r a p l o i d and
h e x a p l o i d wheats and from t h e r e s u l t s o f c r o s s e s between t h e former, genus
A e g il o p s and T r i t i c u m .
The method c o n s i s t s o f c r o s s i n g two s p e c i e s w it h
t h e same o r d i f f e r e n t chromosome numbers and d e t e r m i n i n g chromosome p a i r ­
ing i n t h e Fj h y b r i d .
i n whole o r i n p a r t .
Chromosomes which p a i r a r e c o n s i d e r e d t o be r e l a t e d
Those which do n o t p a i r a r e u n r e l a t e d .
The method
has been used t o d e t e r m i n e genome homologies o f s u p p o s e d l y d i f f e r e n t
species.
As a r e s u l t , t h e wheat s p e c i e s have r e c e n t l y been r e c l a s s i f i e d . -
M or ris and S e a r s (1967) and J e n k i n s (1966) have r e c e n t l y reviewed
c l a s s i f i c a t i o n of wheats.
Both sou rces a g r e e t h a t Bowden's (1959) c l a s s i ­
f i c a t i o n i s t h e most r e a l i s t i c .
Bowden's ' c l a s s i f i c a t i o n abandons th e o l d
genus A e gi lo ps and i n c l u d e s i t s s p e c i e s i n t h e genus T r i t i c u m .
According
t o t h i s c l a s s i f i c a t i o n t h e c u l t i v a t e d wheats a r e grouped i n t o f o u r s p e c i e s
(Tab le I ) .
'
^
)
)
)
)
)
A second r e s u l t o f i n t e r s p e c i f i c c r o s s i n g has been t h e ass ignm en t o f
genome formula ba se d on chromosome homology.
Kihara (1924) and Gaines and
Aase (1926) and A as e, (1930) i n d e p e n d e n t l y proposed t h a t t h e c u l t i v a t e d
Tabl e I .
Species
The grou ps o f v a r i e t i e s
and S e a r s (1 96 7) 0
_
V arietalGroup
--
T . monoc o c cum L.
T . tu r q i d u m L 0 .
T 0 t i m o p h e e v i i (Zhuk.) Zhuk.
v a r timopheevii.
v a r zhu kovskvi (Men &Er.)
M or ris & Sears, comb. nov.
T . a e s t i v u m L. em T h e l l .
/
( c u l t i v a r s ) o f t h e genus T r i t i c u m 0
A f t e r Morris
Based On
Common Name
T. monoco ccum L.
E in ko rn
d ic o c c o n
T . d ic o c c o n Schrank (T. dicoccum
Schrank''
Emmer
durum
T . durum D e s f .
Durum
tu rg id u m
T. turqi du m L.
Pou lard wheat
polonicum
T . polonicum L.
P o l i s h wheat
carthlicum -
T. c a r t h l i c u m Nevski (T„ pers icum
Vav.'')
• P e r s i a n wheat
T . ti m o p he ev i Zhuk.
None
T1. zhukovskvi Men. & E r .
None
spelta
T . s p e l t a L. + T. madia Dek. & Men.
Spelt
vavilovii
T. v a v i l o v i Jakubz
None
ae s ti v u m
T. ae s ti v u m L. (T. v u l q a r e H os t.
T. s a ti v u m Lam.)
Common wheat
compactum
sphaerococcum.
T . compactum H o s t .
T. sphaerococcum P e r c .
Club wheat
Shot wheat
=
—
——
5
wh eats had t h e f o l l o w i n g genome fo r m u l a:
D i p l o i d s p e c i e s , AA; T e t r a p l o i d
s p e c i e s , AABB; and h e x a p l o i d s p e c i e s , AABBDD.
This h y p o t h e s i s , known as
t h e ABD h y p o t h e s i s , has been amply co n fir m ed by many w o r k e r s „
Pres uma bly , a l l o p o l y p l o i d s p e c i e s a r e b u i l t up by i n t e r s p e c i f i c c r o s s ­
ing from two o r more d i p l o i d s , fo ll o w e d by chromosome d o u b l i n g .
h e l d t o be th e ca se i n w h e a t.
Sax and Sax (1924) c r o s s e d A eq il oo s
c v l i n d r i c a w i t h t h e common s p r i n g wheat v a r i e t y M a r q u i s .
duced a few s e e d .
Such i s
The F]_ pr ogeny were c o m p l e t e l y s t e r i l e .
The c r o s s p r o ­
When p o l l e n
m o t h e r c e l l s were examined c y t o l o g i c a l l y , 6 o r 7 b i v a l e n t s and 20 o r 21
u n i v a l e n t s were found a t metaphase I o f m e i o s i s .
This i n d i c a t e s t h a t one
o f t h e genomes o f A. c v l i n d r i c a i s s i m i l a r t o one o f t h e genomes o f common
w he at .
T h e r e f o r e , A e qi lo o s was th e s o u r c e o f one o f t h e genomes o f common
wheat.
B l e i r (1928) c r o s s e d A. c v l i n d r i c a by T. turqi du m and found no
pairs,
i n d i c a t i n g genome homol o g i e was between one o f t h e genomes of
A e q il o o s and t h e D genome o f h e x a p l o i d w hea t.
McFadden and S e a r s (1944) i d e n t i f i e d t h e s o u r ce o f t h e D genome as
A e g il o p s s q u a r r o s a .
They c r o s s e d T. d i c o c c o i d e s by A. s q u a r r e s a and
o b s e r v e d t h a t t h e a m p h i d i p l o i d c l o s e l y r es em b le d T. a e s ti v u m c u l t i v a r
spelta.
This a m p h i d i p l o i d had good p a i r i n g when c r o s s e d w i t h I . a e s t i v u m .
Thompson (1931) c r o s s e d T. monococcum by T. durum and found seven
p a i r s p l u s se ve n u n i v a l e n t s , th us e s t a b l i s h i n g T. monococcum as th e so ur ce
o f t h e A genome.
S a r k a r and S t e b b i n s (1956) s u g g e s t e d t h a t on th e b a s i s
of morphological d i f f e r e n c e s , Triticum s p e lt o id e s
was t h e s o u r c e o f t h e B genome.
(Aeg il op s s p e l t o i d e s )
C ytological in v e s tig a tio n s of crosses
w i t h T. a e s ti v u m have te n d e d t o s u p p o r t t h i s view.
-
6
-
A ne up loi dv i n Wheat:
Sears
(1939) found two h a p l o i d p l a n t s i n th e F]_ pr o ge n y o f a cr o s s
between S e c a l e c e r e a l e and T r i t i c u m a e s t i v u m var„ Chinese S p r i n g .
One
o f th e h a p l o i d s was female s t e r i l e b u t t h e o t h e r s e t 14 s e e d upon p o l l i ­
n a t i o n by Chine se S p r i n g „
S e a r s o b t a i n e d 13 p l a n t s from t h i s s e e d .
These
13 p l a n t s produced 5 monosomiess I doub le monosomic, I monosomic and
t r i s o m i c , 2 do ub le monosomic and t r i s o m i c , I double monosomic p lu s r i n g o f
four,
I double monosomic p lu s dou ble t r i s o m i c p lu s r i n g /of f o u r plus
n u l l i s o m i c , and 2 normal p l a n t s .
The use o f a n e u p l o i d s o f wheat in g e ­
n e t i c s t u d i e s r e c e i v e d a m a jo r impetus from t h i s s t u d y .
By 1954, Sears
had d e v e l o p e d t h e com plete s e r i e s o f n u l l i s o m i c s , monosomies, t r i s o m i c s
and t e t r a s o m i c s .
In a d d i t i o n , t e l o s o m i c s and is os o m ic s were d e s c r i b e d ^
These a n e u p l o i d s have been used e x t e n s i v e l y in d e t e r m i n a t i o n s o f chromo­
somes c a r r y i n g p a r t i c u l a r g e n e s .
■
Ausemus, McNeal and Schmidt (1967) have r e c e n t l y re v ie w e d th e l i t e r ­
a t u r e conc er ned w i t h wheat g e n e t i c s .
T h e i r p a p e r shows t h a t a n e u p l o id s
have been used a l m o s t e x c l u s i v e l y in a s s i g n i n g genes to a p a r t i c u l a r wheat
chromosome.
'
Sears
_
(1954, 1966) used c r o s s e s o f n u l l i s o m i c and t e t r a s o m i c Chinese
S p r i n g t o show t h a t t h e 21 d i f f e r e n t chromosomes of h e x a p l o i d wheat f a l l
i n t o se ven homoeologous grou ps o f t h r e e .
The t e t r a s o m i c can compensate
f o r th e n u l l i s o m i c o f e ac h o f t h e o t h e r chromosomes i n t h e same group.
These r e s u l t s were s u p p o r t e d by t h e work o f Okamoto and S e a r s (1962) in
^
which t h e y found t h a t p a i r i n g in h a p l o i d s was l a r g e l y between chromosomes
i n t h e same homoeologous g r o u p .
)
S ea r s (1958, 1966) and Okamoto. and S ear s
7
( 1962) d ev el op ed a s y st e m o f chromosome numbering based on i d e n t i f i c a t i o n
o f genomes as A, B5 o r D and numbering o f t h e homoeologous groups from one
to seven.
This s y st em i s now w i d e l y a c c e p t e d .
There was some doubt a b o u t
th e c o r r e c t d e s i g n a t i o n o f chromosomes 2A and 2B, b u t t h i s was r e s o l v e d
in a r e c e n t paper,
( R i l e y and Chapman, 19 6 6 ).
Only a few c a s e s o f a n e u p l o i d y i n t e t r a p l o i d wheats have been r e ­
ported.
Tsunewaki (1963) has d e s c r i b e d a t e t r a p l o i d l i n e d e r i v e d from t h e
durum v a r i e t y Melanopus which has 13 normal p a i r s p lu s two t e l o s o m i c
chromosomes.
One o f t h e t e l o s o m i c s was f o r t h e r i g h t arm and th e o t h e r
f o r t h e l e f t arm.
The o n l y f e r t i l e d e r i v a t i v e s o f t h i s l i n e were p l a n t s
w i t h 13 p a i r s p l u s two t e l o s o m i c s ■(I l e f t and I r i g h t ) .
K ih a r a and
Tsunewaki (1962) p ro du ced t r i s o m i c s by t r e a t i n g Kha pli emmer w i t h th e
mutagen NpO.
The t r a n s m i s s i o n o f th e t r i s o m i c s was lower t h a n f o r c o r r e ­
s po nd in g t r i s o m i c s o f h e x a p l o i d w hea t.
Longwell and S e a r s
(1963) were
a b l e to produce n u l l i s o m i c s i n t e t r a p l o i d wheat by adding a p a i r of com­
p e n s a t i n g t e t r a s o m i c s from t h e o t h e r genome.
So f a r , a n e u p l o i d s have
c o n t r i b u t e d l i t t l e t o g e n e t i c s t u d i e s a t t h e t e t r a p l o i d chromosome l e v e l .
Haplosomics and e s p e c i a l l y d i p l o s o m i c s may o f f e r promise i n th e s t u d y
o f t e t r a p l o i d wheat c y t o g e n e t i c s .
For example, th e chromosomes from th e
D genome cou ld be s t u d i e d i n d i v i d u a l l y i f D hapl osomics o r D d ip l o s o m ic s
f o r ea ch o f th e s ev en D genome chromosomes were a v a i l a b l e .
Matsumura
(1952b) produced a number o f 29 chromosome p l a n t s from a p e n t a p l o i d wheat
cross.
These ha p l o so m ic s were used t o s t u d y th e i n h e r i t a n c e o f head t y p e ,
l e n g t h o f glume, stem s o l i d n e s s , s i z e o f p o l l e n g r a i n s and t i l l e r i n g
ab ility ,
as d e t e r m i n e d by chromosomes i n t h e D genome.
8
Matsumuraa a l s o r e p o r t e d a 30 chromosome p l a n t (D d i p l o s o m i c ) .
d i p l o s o m i c p l a n t p o s s e s s e d t h e t e t r a p l o i d complement o f I .
This
turqidum
c u l t i v a r polonicum and a s i n g l e p a i r o f D genome chromosomes from T.
aestivum c u l t i v a r s p e l t a .
The D ha p l o so m ic s v e r y q u i c k l y r e v e r t e d t o 14 p a i r s , b u t th e D
d i p l o s o m i c was r e l a t i v e l y s t a b l e .
If f e r t i l i t y is not lim itin g ,
i t s hou ld
be p o s s i b l e t o use t h e D d i p l o s o m i c s f o r s t u d i e s where r e l a t i v e l y l a r g e
p opulations are d e s ir e d .
I n f o r m a t i o n i n th e l i t e r a t u r e r e g a r d i n g the
f r e q u e n c y w i t h which D d i p l o s o m i c s can be e x p e c t e d from p e n t a p l o i d h y b r i d s
is l i m i t e d .
Those s t u d i e s which have been p u b l i s h e d a r e n o t e x t e n s i v e
enough t o g i v e r e l i a b l e e s t i m a t e s o f t h e p o p u l a t i o n s i z e s n e c e s s a r y to
produce D d i p l o s o m i c s .
P e n t a p l o i d Wheat C r o s s e s ;
K ih ar a (1921, 1924) c r o s s e d t h e T r i t i c u m s p e c i e s T. tu r q i d u m by
T. a e s ti v u m c u l t i v a r s p e l t a and i n v e s t i g a t e d t h e chromosome numbers in th e
Fj and Fg .
He s e p a r a t e d t h e Fg pr ogeny i n t o t h r e e g r o u p s .
p la n ts w ith M j i plus
•14 j j .
(l to 7 ) j ,
l a t e r g e n e r a t i o n s u s u a l l y r e v e r t e d to
Where t h e r e were 1 4 j j p lu s Xj j p l u s
r e v e r t e d t o 21 p a i r s .
In th o s e
(7
- X ) j , t h e pr ogeny r e ­
The i n t e r m e d i a t e gr ou p was h i g h l y s t e r i l e and
u s u a l l y d i s a p p e a r e d from th e p o p u l a t i o n .
K ih a r a (1924) n o te d a g r e a t e r f r e q u e n c y o f p a r e n t a l chromosome com­
:
b i n a t i o n s i n t h e Fg t h a n would be e x p e c t e d on th e b a s i s o f random d i s t r i ­
bution of u n iv a le n ts .
)
i
)
)
I
J e n k i n s and Thompson (1930) looked a t chromosome numbers in t h e Fg
o f a s m a l l sample (37 p l a n t s ) from t h e c r o s s o f T. a e s ti v u m by T„ turqi du m
-
c u l t i v a r emmer.
9
-
/
T h eir r e s u l t s supported those of K ih ara„
K ih ar a and Matsumura (1942) s u g g e s t e d t h a t one r e a s o n f o r f a i l u r e o f
t h e o r e t i c a l e x p e c t a t i o n s to ag ree w i t h observedvwas u n i v a l e n t e l i m i n a t i o n
a t an ap ha se I I and l a t e r s t a g e s o f m e i o s i s . ■ U n i v a l e n t s t e n d t o be l e f t
o u t o f t h e n u c l e u s a t t e l e p h a s e I I due t o l a g g i n g .
a p p e a r as m i c r o n u c l e i i n t e t r a d s .
Such chromosomes
These m i c r o n u c l e i d e t e r i o r a t e and a r e
l o s t from t h e g a m e t e s .
Thompson and Cameron (1928) c r o s s e d t h e s p r i n g wheats Marquis and
C hin es e w i t h s p r i n g emmer and Iu m i ll o durum w i t h th e o b j e c t i v e o f d e t e r ­
mining th e f r e q u e n c y w i t h which u n i v a l e n t s a r e pa s s ed t h r o u g h th e male
and female ga m e te s .
The f r e q u e n c y w i t h which 0, I , 2 , 3, 4, 5, 6 and 7
u n i v a l e n t s were p a s s e d was d e t e r m in e d by b a c k c r o s s i n g
each of t h e i r re s p e c tiv e p a r e n t s .
p e n t a p l o i d s to
The b a c k c r o s s progeny were examined
c y t o l o g i c a i l y and t h e number o f u n i v a l e n t s in ea ch BC^ p l a n t was d e t e r ­
mi ned.
F u n c t i o n a l gametes from t h e p e n t a p l o i d F^ h y b r i d p a s s e d zero to
seven u n iv a le n ts with a h igher frequency than expected.
u n i v a l e n t numbers were c o r r e s p o n d i n g l y r e d u c e d .
Intermediate
The most f r e q u e n t gamete
c l a s s was t h a t w i t h 14 chromosomes (i. e. no u n i v a l e n t s ) .
There were d i f ­
f e r e n c e s between t h e c r o s s e s i n t h e f r e q u e n c i e s w i t h which u n i v a l e n t s
were p a s s e d .
The a u t h o r s conc lu ded t h a t " i f gametes w i t h t h e f r e q u e n c i e s
found mate a t random, t h e r e s u l t s s h o u l d be i n g e n e r a l l i k e t h o s e which
have been r e p o r t e d f o r Fg" .
Love (1940) i n v e s t i g a t e d c r o s s e s o f M a r q u i s , Hope, RL-729 and
M a r q u i l l o h e x a p l o i d s w i t h t h e durum v a r i e t y I u m i l l o .
From t h e s e c r o s s e s ,
336 p l a n t s i n t h e Fe,, F5 and Fy were examined c y t o l o g i c a i l y .
The I u m i l l o
10
p a r e n t c a r r i e d r u s t r e s i s t a n c e and t h e pr og eny had been s e l e c t e d f o r r u s t
r e s i s t a n c e and h e x a p l o i d p a r e n t p l a n t c h a r a c t e r i s t i c s .
The f o l l o w i n g
chromosome numbers were found:
140, and 6
p l a n t s w i t h chromosome numbers Ofv28^ 38
chromo-
so m es , r e s p e c t i v e l y . ' In a d d i t i o n t h e r e were 14 p l a n t s w i t h a h e t e r o morphic b i v a l e n t ( p a i r i n g a t metaphase I o f m e io s is o f a normal and
t e l o s o m i c chromosome p a i r ) ,
14 p l a n t s w i t h t r i v a l e n t s , 10 p l a n t s w ith
q u a d r i v a l e n t s , 8 p la n ts with isosom ics, 3 p la n ts with fragments, I p la n t
w i t h two t r i v a l e n t s , and 2 p l a n t s w i t h two q u a d r i v a l e n t s .
Evidently,
w h i l e chromosome numbers te n d t o ap pr o ac h t h e p a r e n t a l number, t h e r e a r e
s e v e r a l i n t e r m e d i a t e co m b in at i o n s which a r e v i a b l e .
Summary
S p e c i e s c r o s s e s i n t h e genus T r i t i c u m have l e d t o s e v e r a l im p o r ta n t
conclusio n s.
1.
The' s i m i l a r i t i e s between t h e s p e c i e s o f A e q il o p s and
T r i t i c u m w a r r a n t t h e i r i n c l u s i o n in th e same g e n u s .
2.
The s p e c i e s o f t h e genus T r i t i c u m form a p o l y p l o i d s e r i e s
from d i p l o i d (n=7) t o h e x a p l o i d (n=2l)„
In t h e h e x a p l o i d
t h e t h r e e genomes a r e composed o f seven homoeologous
gr o up s o f t h r e e .
T h e r e f o r e , h e x a p l o i d wheat i s an a u t o ­
a l l o p o l y p l o i d w i t h many o f t h e genes p r e s e n t on chromo­
somes o f one genome d u p l i c a t e d on chromosomes o f a n o t h e r
genome.
3.
Use o f a n e u p l o i d s has made a c o n s i d e r a b l e c o n t r i b u t i o n
t o th e u n d e r s t a n d i n g o f t h e c y t o l o g y and g e n e t i c s of
11
w heat.
T h e i r c o n t i n u e d use s h o u ld c o n t r i b u t e t o
f u r t h e r advances.
4,
The p r e s e n c e o f s i m i l a r g e n e t i c m a t e r i a l in d i f f e r e n t
genomes a l lo w s f o r c o n s i d e r a b l e b u f f e r i n g a g a i n s t
gene l o s s and al low s u n u s u a l chromosome c o m b in at io n s
to occur.
5.
P e n t a p l o i d c r o s s e s have d e m o n s t r a t e d t h a t w h ile
chromosome numbers i n l a t e r g e n e r a t i o n s a p p r o ac h es th o s e
o f p a r e n t a l t y p e s , many i n t e r m e d i a t e chromosome
co m b in a ti o n s can be m a i n t a i n e d .
P l a n t s w i t h i n t e r m e d i a t e chromosome com bin ati on s coul d c o n t r i b u t e
s i g n i f i c a n t l y t o t h e s t u d y o f wheat g e n e t i c s .
MATERIALS AND METHODS
E x p e rim en t I
Seeds d e r i v e d from s i n g l e head rows were used f o r p a r e n t s i n a l l
crosses.
All c r o s s e s were made in th e g r ee nh o u s e d u r i n g the. w i n t e r of
1964- 65.
They were as f o l l o w s :
1.
T h a t c h e r s p r i n g wheat X Wells durum.
2 . . T h a t c h e r s p r i n g wheat X Dakota durum.
3.
T h a t c h e r s p r i n g wheat X Langdon durum.
,
4.
( I . ti m o p h e e v i R e s t o r e r I X Marqui s 3) X C e r e s ^ ) X Wells
durum.
Cros s number 4 was b a c k c r o s s e d t o Wells durum as th e male i n th e
summer o f 1965.
v
This l a t t e r c r o s s w i l l h e r e a f t e r be r e f e r r e d t o as
(Cere s X W e l ls ) X W e l l s .
The Fj was grown in th e g ree nh o us e d u r i n g th e summer o f 1965.
from ea ch p l a n t were k i l l e d and f i x e d in Newcomer's S o l u t i o n ,
19 5 3 ) .
P o l l e n mot her c e l l s
technique of B elling
Heads
(Newcomer
(PMC's) were smeared by th e i r o n ac e to ca r m in e
( 1 92 1 ) .
Chromosome p a i r i n g was d e t e r m i n e d a t
me tap has e I o f m e i o s i s and checked a g a i n s t t o t a l number o f chromosomes a t
an ap ha se I .
The number o f c e l l s examined v a r i e d bu t was s u f f i c i e n t to
assure correct c l a s s i f i c a t i o n .
Where t h e r e were i n s u f f i c i e n t w e ll
'
sq u a s h e d c e l l s f o r a c c u r a t e c o u n t s , th e p l a n t was e x c l u d e d from the
'
resu lts.
)
)
The Fg' s from t h e v a r i o u s c r o s s e s were grown i n t h e g r ee nh o u s e d u r ing th e wirr ter o f 1965-66.
Heads were c o l l e c t e d and chromosome combina-
)
t i o n s d e t e r m i n e d , as d e s c r i b e d e a r l i e r .
)
grown i n t h e f i e l d i n 1966 and .chromosome co m bin ati on s d e t e r m i n e d .
)
)
)
•
A few Fg and BCj f a m i l i e s were
-
13
-
Experiment H s
A s e t o f D genome t e t r a s o m i c s in t h e h e x a p l o i d v a r i e t y Chinese S p r in g
were k i n d l y s u p p l i e d by D r „ E„ R0 S e a r s „
Seed s u p p l i e d by D r 0 Se ars was
p l a n t e d i n t h e g r e e n h o u s e in th e s p r i n g o f 1965=
The t e t r a p l o i d v a r i e t i e s
Wells and Dakota durum were a l s o seed ed a t t h i s time = Heads from each
t e t r a s o m i c p l a n t were examined t o c o n f i r m t h e e x p e c te d chromosome com­
b i n a t i o n o f 2 0 n + I jy =
Lin es t e t r a s o m i c f o r each o f t h e se v en D genome
chromosomes were ea ch c r o s s e d t o Wells and Dakota durum=
The durum
v a r i e t i e s were used as p o l l i n a t o r s =
The Fj s ee d was p l a n t e d i n t h e g r ee n h o u s e in th e autumn o f 1965=
Each
p l a n t was examined f o r t h e e x p e c t e d chromosome co m b in at i o n of
1 5 j j + 6 j=
The Fg s ee d s from p l a n t s w i t h 1 5 j j + 6 j a t metaphase I of
m e i o s i s were se ed ed i n t h e f i e l d in 1966=
Each Fg row r e p r e s e n t e d t h e
pr o g en y o f a s i n g l e Fj p l a n t „
Heads were c o l l e c t e d .from random F^ p l a n t s in each row.
As th e head
was c o l l e c t e d , t h e p l a n t and th e head sample were marked w i t h t h e row and
p l a n t number=
The chromosome co m b in at i o n o f each Fg p l a n t was d et er m in e d
as d e s c r i b e d p r e v i o u s l y =
At m a t u r i t y Fg p l a n t s were p u l l e d and t h r e s h e d ,
and t h e s ee d was bagged s e p a r a t e l y =
The Fg s ee d s from Fg p l a n t s w i t h chromosome c o m b in at io n s o f from
1 5 j j + I j to 1 5 j j + 5 j were p l a n t e d i n t h e g ree nh ou se d u r i n g t h e f a l l and
w i n t e r o f 1966=
Heads from ea ch Fg p l a n t i n a f a m i ly were c o l l e c t e d as
b e f o r e and t h e chromosome c om b in at io n was d e t e r m in e d = At m a t u r i t y , each
Fg p l a n t was examined = H e i g h t , number o f t i l l e r s ,
and head ty p e were recorde d=
fertility,
awning
- 14 -
A few F4 f a m i l i e s were grown from s e l e c t e d F3 p l a n t s d u r i n g the
summer o f 1967 = Chromosome co m b in at i o n s and g r o s s morphology were r e ­
co rd ed O
RESULTS
E x p erim en t I :
When h e x a p l o i d s p r i n g wheat i s c r o s s e d t o t e t r a p l o i d durum wheat,
14 p a i r s p l u s se ve n u n i v a l e n t s ar e e x p e c t e d a t metaphase I o f m e io s is in
F]_ p l a n t s .
A ll
p l a n t s showed t h i s c o n f i g u r a t i o n , i n d i c a t i n g t h a t ( I )
t h e s p r i n g wheats and durum wheats used i n th e c r o s s e s had t h e ex p ec te d
chromosome nu mb ers , and (2 ) t h a t c r o s s e s were s u c c e s s f u l .
The f r e q u e n c y w i t h which Fg p l a n t s w i t h v a r i o u s chromosome c o n f i g u ­
r a t i o n s were o b s e r v e d a r e r e p o r t e d in Table I I .
A chi square R X C ta b le
( S t e e l and T o r r i e , I960) was used t o d e t e r m in e i f th e t h r e e c r o s s e s d i f ­
f e r e d i n t h e f r e q u e n c y w i t h which v a r i o u s chromosome co m b in a ti o n s o c c u r ­
red.
The c h i s q u a r e v a l u e o f 50 .8 7 (Table I I ) has a p r o b a b i l i t y o f b e ­
tw e e n , -0.75 and 0 . 9 0 -
T h e r e f o r e , th e durum v a r i e t y used i n a c r o s s d i d n o t
a f f e c t t h e f r e q u e n c y w i t h which v a r i o u s gametes were combined in Fg piante. ■
Some 171 o f t h e 285 p l a n t s o r 60 p e r c e n t , had 14 j j , o r 14-j-j + ( l t o 7 ) j .
P l a n t s w i t h ea ch o f t h e p o s s i b l e 21 chromosomes r e p r e s e n t e d a t l e a s t once
made up 23.5% o f t h e s am pl e.
During m e i o s i s t h e 1 4 j j o f chromosomes i n t h e p e n t a p l o i d h y b r id s
s h o u l d s e g r e g a t e n o r m a l l y , b u t t h e s ev en u n i v a l e n t s may go t o e i t h e r pole
o r become l o s t ( F i g u r e I ) .
The f r e q u e n c y w i t h which 14, 15, 16, 17, 18,
19, 20, o r 21 chromosome gametes ar e formed can be d e t e r m i n e d by c r o s s i n g
th e p e n t a p l o i d t o e i t h e r t h e t e t r a p l o i d o r h e x a p l o i d p a r e n t .
In t h i s
s t u d y t h e F^ p e n t a p l o i d Ceres X Wells was c r o s s e d as female t o Wells durum
as m a le .
The f r e q u e n c y w i t h which u n i v a l e n t s were p a s s e d t h r o u g h the
female gametes was d e t e r m i n e d by examining t h e BC]_ progeny c y t o l o g i c a l l y .
- 16 -
Tabl e I I .
Chromosome
Pairina
14 I I
14I I + i i
I 4II + 2i
I 4 H + 3I
14I I + 4 I
I 4H + si
14I I + 6I
I 4H + vi
Observed f r e q u e n c y o f chromosome c o m b in at io n s in Fg
pr og en y o f t h r e e spring- wheat by durum c r o s s e s ,
Thatcher X Thatcher X Thatcher X
Wells
Lanqdon
Lakota •
2
2
3
12
5
9
12
11
8
16
5
8
7
13
11
4
14
5
3
3
. 9 .
2
4
3
O
7
4
10
10 '
6
12
Sub
Total
171
O
I
I
2
.I
2
3
O
4
O
5
2
2
6
O
O
O
O
I
4
O
O
O
0
4
11
O
I
I
I
3
I
16
27
O
O
O
O
3
O
O
2
I
4
O
O
O
2
5
0
0
2
3
12
17
19li + i i
1 9 n + 2i
O
O
I
5
O
O
I
O
O
I
4
O
I
3
O
O
O
I
O
O
O
0
0
2
10
0
I
4
2011
20ii + Il
O
I
O
2
O
I
0
4
4
2111
O
O
O
0
0
Totals
71
135
79
285
Chi Square from R X C t a b l e ' = 50.87. , P-= 0 . 7 5 to 0 .9 0
285
15I I
15n + Ii
1 5 l l + 21
1511 + 3l
15H + 4I
15n + Si
1 5 n + Si
16n
16n + ii •
16I I + 21
1 6 n + 3I
16ll + 4I
i 6 n + Sz
17i i
iv ii
IVlI
17n
iv ii
+ U
+ 2l
+ 3I
+ 4I
1.811
i8 ir + ii
i8 n + 2 i
i s i i + 3I
19n
O
2
3
3
7
2 ■
3
Total
Observed
7
26
31
29
31
23
15
9
49
0
I
I
I
8
12
5
Figure
I
Anaphase I o f m e i o s i s i n T h a t c h e r X durum c r o s s e s .
A, seven u n i v a l e n t s on t h e metaphase p l a t e i n an Fg p l a n t
w i t h 1 4 j i + 7 j , ap p r o x . 1250X. B, f o u r u n i v a l e n t s
d i v i d i n g a t anapha se I i n an Fg p l a n t w i t h 1 5 u + 4 j ,
a p p r o x . 1000X.
18
I f one assumes t h a t none o f t h e u n i v a l e n t s ar e l o s t d u r i n g gamete forma­
t i o n , t h e p r o b a b i l i t y t h a t a p a r t i c u l a r gamete c o n t a i n s 0 , I , 2 , 3 , 4 , 5 ,
7
6 , o r 7 u n i v a l e n t s would be g i v e n by t h e b i n o m ia l formulae (x + y) ,
where x i s th e p r o b a b i l i t y t h a t a gamete c o n t a i n s a g i v e n u n i v a l e n t and y
i s t h e p r o b a b i l i t y t h a t i t does n o t .
Assuming no l o s s , t h e p r o b a b i l i t i e s
r e d u c e t o t h e b i n o m i a l c o e f f i c i e n t s I , 7, 21, 35, 35, 21, 7 and I gametes
w i t h 0, I , 2, 3, 4 , 5,. 6 and 7 u n i v a l e n t s , r e s p e c t i v e l y .
When t h e s e
p r o b a b i l i t i e s a r e compared w i t h t h e a c t u a l f r e q u e n c i e s , i t becomes obvious
t h a t u n i v a l e n t l o s s does o c c u r (Tab le I I I ) . - There a r e more p l a n t s w it h
0, I and 7 u n i v a l e n t s t h a n e x p e c t e d and few er p l a n t s w i t h 2 , 3, 4 and 5
u n iv a le n ts than expected.
These r e s u l t s s u g g e s t t h a t x i s c o n s i d e r a b l y s m a l l e r t h a n y as a
r e s u l t of u n iv a le n t l o s s .
In o r d e r t o t e s t t h e h y p o t h e s i s :
There i s a
c o n s i d e r a b l e l o s s o f u n i v a l e n t s , bu t t h o s e r e t a i n e d a r e d i s t r i b u t e d a t
random and i n d e p e n d e n t l y , l e t us assume t h a t th e o b s er v ed v a l u e o f 0.225
f o r t h e gr oup w i t h ze ro u n i v a l e n t s i s c o r r e c t .
Then t h e v a l u e o f x must
be e q u a l t o t h e s e v e n t h r o o t o f 0.2 2 5 o r 0 . 8 0 8 .
Then y must be eq u a l t o
( I - 0. 8 0 8 ) o r 0 . 1 9 2 .
C o n s e q u e n t ly t h e b i n o m i a l formula becomes
( 0 .8 0 8 + 0 .1 9 2 )7 and we e x p e c t 0 .2 2 5 , 0 .0 5 3 3 8 , 0 .0 1 2 7 , 0 .0 0 3 0 , 0 .0 0 0 7 ,
0 . 0 0 0 1 7 , 0 .0 0 0 0 4 and 0.000009 o f th e b a c k c r o s s sample t o have 0, I , 2, 3,
4 , 5 , 6 and 7 u n i v a l e n t s , r e s p e c t i v e l y .
O b v io u s ly t h i s e q u a t i o n does n o t
f i t t h e o b s e r v e d v a l u e s and, t h e r e f o r e , t h e u n i v a l e n t s r e t a i n e d a r e no t
d i s t r i b u t e d a t random and may n o t a s s o r t i n d e p e n d e n t l y .
The b e s t e s t i m a t e
o f t h e number o f u n i v a l e n t s p a s s e d t h r o u g h th e female c o r r e s p o n d s to th e
o b s e r v e d v a l u e s and t h e s e f r e q u e n c i e s w i l l be used in s u b s e q u e n t c a l c u ­
19 -
latio n s.
The p e n t a p l o i d s h o u l d a l s o have been used as male i n b a c k c r o s s e s
t o Wells durum so t h a t t h e f r e q u e n c y w i t h which u n i v a l e n t s a r e pas se d
t h r o u g h t h e male coul d have been d e t e r m i n e d „
done.
U n f o r t u n a t e l y t h i s was no t
However, i f we assume t h a t u n i v a l e n t s a r e p as s ed t h r o u g h male
gametes w i t h t h e same f r e q u e n c i e s as t h r o u g h female gametes t h e expected
f r e q u e n c i e s o f v a r i o u s chromosome co m b in at i o n s can be c a l c u l a t e d and com­
p a r e d w i t h t h e a c t u a l f r e q u e n c i e s o b s e r v e d i n th e F^.
l a t e t h e s e f r e q u e n c i e s ' a two-way t a b l e was s e t up.
In o r d e r t o c a l c u ­
The f r e q u e n c i e s w ith
w hich v a r i o u s numbers o f u n i v a l e n t s o c c u r r e d i n gametes i n Tabl e I I I were
p l a c e d a c r o s s t h e t o p and a l s o along t h e s i d e o f th e two-way t a b l e .
r e s u l t s i n a t a b l e w i t h 64 c e l l s .
This
The f r e q u e n c y w it h which a zygote
o c c u r s was th e p r o d u c t o f t h e gamete f r e q u e n c i e s i n each row and column
o f th e t a b l e .
In most c a s e s , t h e r e was more t h a n one c e l l w i t h th e same
t o t a l number o f chromosomes and i t was n e c e s s a r y t o add t h e f r e q u e n c i e s
i n th e c e l l s w i t h t h e same chromosome numbers (Appendix Tabl e I ) .
This
t o t a l f r e q u e n c y was t h e n m u l t i p l i e d by 285 t o o b t a i n t h e c a l c u l a t e d
column o f Table IV„
These d a t a i n d i c a t e t h a t e i t h e r male gametes do n o t p a s s u n i v a l e n t s
w i t h t h e same f r e q u e n c y as do female g a m e t e s , o r t h a t th e Fg data, may not
have been e x t e n s i v e enough (Table IV).
The c h i s q u ar e v a l u e s s u g g e s t t h a t
I
t h e r e were t o o few p l a n t s in th e 28 and 35 chromosome g r oup s and too many
)
p l a n t s i n t h e 31 chromosome g ro u p .
^
)
)
)
>
A p l a n t w i t h 35 chromosomes cou ld have t h e com binatio ns' 14 j j + 7 j ,
1 5 j j + 5 j , 16%% + 3% o r 17%% + 1 % .
I t would be o f i n t e r e s t to d et er m in e
- 20 -
Table I I I .
Chromosome
Pairinq
Chromosome numbers i n BCi progeny o f a (Ceres X Wel ls)
X Wells c r o s s .
Number
Observed
F r eq u en cy
In P e r c e n t
I 4II
16
2 2 .5
E x p e c te d Frequency
(Binomial C o e f f i c i e n t s )
Percent
0 .8
14 I I + I I
11
1 5 .5
5.5
14ll + 2;
9
1 2 .7
14I I + 3%
8
1 1 .3
2 7 .3
14I I + 4 I
12
17.0
2 7 .3
1 4 u + 5%
5
7 .0
1 6 .4
I 4 H + 6x
3.
4.2
5.5
I4II + 71
7
9 .8
71
1 0 0 .0
Total
'
.
1 6 .4
0 .8
1 0 0 .0
- 21
Table IV.
Numbers o f chromosomes o b s e r v e d in Fg p l a n t s compared t o
e x p e c t e d number bas ed on number o f u n i v a l e n t s passed
t h r o u g h female gametes i n BCj, progeny o f a
(Ceres X We ll s) X Wells c r o s s , and random zygote
formation.
Chromosome
No.
Number o f P l a n t s
Observed
Calculated
Chi
Square
7
14.42
3 .8 2
26
1 9 .8 9
1.88
: 30
31
23.14
2 .6 7
31
36
25.71
4 .1 2
32
35
36.37
0 .0 5
33
34
36.91
0 .2 3
34
26
2 7 .5 6
0 .0 9
35
16
32 .2 9
8 .2 3
36
22
2 4 .4 2
0 .2 4
37
19
16.53
0 .3 7
38
14
11.77
0.54
39
11
11.17
0 .0 0
40
4
4.45
0 .0 4
41
4
2 .3 4
1.18
42
0
2 .7 4
2.74
28
29 '
Totals
P = 0. 02 5 w i t h 14 d . f .
285
285
2 6 .2 0
- 22
i f a l l t h e d e v i a t i o n from e x p e c t e d i n t h i s gr ou p (Table IV) was due t o a
d e f i c i e n c y o f p l a n t s i n one o f t h e s e g r o u p s , o r i f a l l f o u r groups c o n t r i ­
buted e q u a lly .
I n o r d e r t o make t h e above co m par iso n,
i t was n e c e s s a r y t o c a l c u l a t e
t h e p r o b a b i l i t y t h a t two gametes c o n t a i n e d one o r more s i m i l a r chromosomes
■and t h a t t h e s e two gametes form a z y g o t e .
For ex am p le :
supp ose t h a t a
male gamete w i t h 15 chromosomes u n i t e d w i t h a female gamete w i t h 15
chromosomes.
We know t h a t 14 o f th e chromosomes i n ea ch gamete a r e a l i k e .
The r e m a in in g chromosome in each o f t h e gametes could be any one o f the
chromosomes ID, 2D, SD^ 4D, 5D, 6D o r 7D.
is then l / 7 .
The p r o b a b i l i t y t h a t i t i s ID
The p r o b a b i l i t y t h a t th e male c a r r i e s ID and t h a t t h e female
a l s o c a r r i e s ID i s l / 7 x l / 7 o r l / 4 9 .
From th e above c a l c u l a t i o n ,
(Appendix Table I ) , we know t h a t t h e p r o b a b i l i t y o f a 15 chromosome gamete
be i n g mated t o a 15 chromosome gamete i s 0 . 0 2 4 0 .
M u l t i p l y i n g by l / 4 9 we
o b t a i n 0. 000 5 as t h e p r o b a b i l i t y o f 1 5 n o f chromosomes i n a z y g o t e .
The
p r o b a b i l i t y t h a t t h e chromosomes a r e n o t s i m i l a r must be 0 . 0 2 4 0 minus
0. 000 5 o r 0 . 0 2 3 5 .
These z y g o t e s w i l l g i v e p l a n t s w i t h 1 4 j j + 2 j a t
m e tap h as e I o f m e i o s i s ,
Where a d d i t i o n a l u n i v a l e n t s a r e p r e s e n t , as i n gametes w i t h 16 o r
more chromosomes, t h e p r o b a b i l i t i e s a r e more d i f f i c u l t t o o b t a i n .
We must
f i n d a l l p o s s i b l e c o m b in a ti o n s o f seven t h i n g s ta k e n two a t a time f o r 16
chromosome ga m e te s .
Suppose t h e o t h e r gamete has 17 chromosomes.
Then
a l l p o s s i b l e c o m b in a ti o n s o f se ve n t h i n g s t a k e n t h r e e a t a time must be
obtained.
We n e x t p l a c e t h e co m b in at i o n s o f seven t h i n g s t a k e n two a t a
time i n t h e rows o f a t a b l e and t h e co m b in a ti o n s o f se ven t h i n g s ta ke n
-
23
-
t h r e e a t a time i n columns o f t h e same t a b l e .
We n e x t n o te t h e o c c u r r e n c e
o f t h e same chromosome o r chromosomes i n t h e c e l l s o f t h e t a b l e and d e t e r ­
mine t h e f r e q u e n c y o f one and two p a i r s .
F i n a l l y we p r o c e e d , as i n th e
ca se o f t h e mating o f two gametes w it h 15 chromosomes, t o c a l c u l a t e the
f r e q u e n c y o f v a r i o u s chromosome c o m b i n a t i o n s .
The p o s s i b l e gamete
co m b in a ti o n s which co ul d r e s u l t i n d i f f e r e n t chromosome c o m b i n a t i o n s , th e
f r e q u e n c i e s w i t h which t h e y o c c u r and t h e f r e q u e n c y of p a i r i n g a r e .given
in Appendix Table I I .
The p r e c e d i n g c a l c u l a t i o n s were used t o compare t h e e x p e c t e d and
o b s e r v e d f r e q u e n c i e s o f v a r i o u s chromosome co m bin ati on s i n Fg p l a n t s from
T h a t c h e r X durum c r o s s e s (Table V).
some grou ps were most i n e r r o r .
In Table IV th e 35, 31 and 28. chromo­
T h i r t y - f i v e chromosomes co u ld come from
p la n ts with the following c o n f i g u r a t i o n s :
and I T j j + I j .
calculated.
1 4 j j + 7 j , I b j j + 5 j , 16 j j + 3 j
In Ta b le V t h e 16 j j + 3 j g r ou p has seven few er p l a n t s tha n
The o t h e r chromosome co m b in at i o n s do n o t make a s u b s t a n t i a l
c o n t r i b u t i o n t o t h e d e v i a t i o n from e x p e c t e d .
o c c u r i n t h e c o m b in a ti o n s 14 j j
b ilities
+ 3j
T h i r t y - o n e chromosomes can
and 1 5 j j + l j .
Of t h e s e two p o s s i ­
i t i s 1 5 j j + I j which has th e g r e a t e s t d e v i a t i o n from e x p e c t e d .
The 28 chromosome gr oup has t h e same c h i s q u a r e as in t h e e a r l i e r c a l c u ­
l a t i o n bec au se t h e r e a r e no u n i v a l e n t s t o p a i r , t h e r e f o r e , t h e d e v i a t i o n
from e x p e c t e d remains t h e same.
The c h i s q u a r e v a l u e has a p r o b a b i l i t y o f o c c u r r i n g by chance 25% o f
the ti m e „
Th is s u g g e s t s t h a t t h e c a l c u l a t i o n s may n o t be t o o f a r wrong.
P e r h a p s a d d i t i o n a l o b s e r v a t i o n s o f F2 p l a n t s from th e T h a t c h e r X durum
c r o s s e s would have improved t h e f i t .
)
A d d i t i o n a l o b s e r v a t i o n s o f Fg and
- 24
Ta bl e V.
F r e q u e n c i e s o f chromosome co m b in at i o n s o b s er v ed i n t h e Fg p r o g ­
e n i e s o f T h a t c h e r X durum c r o s s e s as compared t o t h e f r e q u e n c i e s
e x p e c t e d , b as ed on u n i v a l e n t s p a s s e d th r o u g h female gametes in a
(C er es X W e l l s ) X Wells c r o s s .
Chromosome
Com bin ation
14n
14n + I %
M n + 21
M n + 3%
M n + 4i
M 11 + S1
I 4II + 6i
14 I I + 7 I
i5 n
i5 n + i%
1511 + 2 I
1 5 n + Si
15ii + 4i
i 5 n + 51
15tt + 6j
16n
16n
16iI
16n
16n
16n
1711
I 7II
17I I
M n
17I I
18n
I8n
I8n
18n
I9n
!O n
19n
20n
20n
21i i
+
+
+
+
+
11
2j
Si
4j
Si'
+
+
+
+
II
2I
Si
4I
+ Ii
+ 2i
+ 3I
+ 11
+ 2i
+ Ii
Number of P l a n t s
Calculated
Observed
7
14 .4 2
26
19.89
22 .1 7
31
22 .5 1
29
31
2 9 .7 2
2 7 .2 2
23
15
9 .3 8
9
13 .5 9
0 .9 7
0
7
3 .1 9
4
6 .4 7
13.22
10
13.34
10
6
9 .3 5
12
11.09
0 .2 3
0
1 .14
I
I
4.79
I
8 .0 4
8
8 .9 8
10.15
16
0
0 .0 8
1 .2 5
0
2
4.07
3
5 .4 1
12
9 .3 5
0 .2 2
0
'
0 .9 7
0
2
2 .3 7
10.71
10
0 .0 6
0
I
0 .4 6
4
4 .3 6
0
0 .0 6
4
2 .3 4
2.74
0
T o t a l Chi Square = 49.161
P = 0 . 2 5 w i t h 35 d . f .
Chi Square
Value
3.818
1.877
3.517
1.871
0.055
0 .6 5 4
3 .3 6 7
1.550
0 .9 7 0
4 .5 5 0
0.9 4 3
0.784
0.836
1.200
0.0 7 5
0.2 3 0
0.017
2 .9 9 9
6 .1 6 4
0.107
3.372
0 .0 8 0
1.250 .
1.053
1.074
0.751
0 .2 2 0
0.9 7 0
0.058
0.047
0 .0 6 0
0 .6 3 4
0.0 3 0
0.060
1.178
2 .7 4 0
- 25
BCj chromosome s e g r e g a t i o n s ar e needed f o r a d e c i s i o n t o be made.
U n i v a l e n t s a r e b e l i e v e d t o g i v e r i s e t o t e l o s o m i c s by m i s d i v i s i o n o f
t h e c e n t r o m e r s a t anap ha se I o r anapha se I I o f m e i o s i s ,
1952b).
(Sears 195 2 a,.
The t e l o s o m i c s can i n t u r n g i v e r i s e t o is os o m ic s by f a i l u r e o f
th e c h r o m a ti d s o f t e l o s o m i c s t o s e p a r a t e ,at anaphase I o r anapha se I I of
m eiosis.
A number o f p l a n t s w i t h i s o s o m ic s o r telosomics were ob se rv ed in
t h e Fg o f T h a t c h e r by durum c r o s s e s (Table V I ) .
M u l i v a l e n t a s s o c i a t i o n s were a l s o o b s e r v e d i n t h e Fg pr ogeny of
p e n t a p l o i d wheat h y b r i d s .
There were 18 p l a n t s w it h q u a d r i v a l e n t s in 356
p l a n t s examined o r 5 . 1 p e r c e n t (Table V I I ) .
p l a n t s , o r 1. 7 p e r c e n t o f th e p r o ge n y.
have been t h e r e s u l t o f t r a n s l o c a t i o n s .
T riv a le n ts occurred in 6
I n some ca s es t h e m u l t i v a l e n t s may
In th e p l a n t w i t h I j y + 12 j j
t h e r e was p r o b a b l y a t r a n s l o c a t i o n between two o f th e chromosomes i n th e
A a n d / o r B genomes.
presence of triso m ics
M u l t i v a l e n t p a i r i n g c o u l d a l s o r e s u l t from th e
( F i g u r e 2) and t e t r a s o m i c s .
No a t t e m p t was made to
i d e n t i f y t h e cause o r c au s es o f m u l t i v a l e n t p a i r i n g i n th e p l a n t s ob­
served in t h i s stu d y .
-
Table VI.
Fr equ enc y o f is o s o m ic s and t e l o s o m i c s i n t h e Fg p r o g e n ie s
o f s p r i n g wheat X durum c r o s s e s .
Cros s
)
)
)
)
Number o f P l a n t s With
Tel osomics
I s o so m ic s
No.
No.
%
%
•
Observed
Fr equ enc y Observed
Frequency
T h a t c h e r X Langdon
4
5.6
2
2 .8
T h a t c h e r X Lakota
5
3 .7
I
0.7
T h a t c h e r X Wells
I
1.3
I
1.3
( C er es X W el ls ) X Wells
O
0 .0
■ I
1.4
10
2 .8
5
1.4
Total
)
26
-
Figure
2
27 -
T r i v a l e n t s a t metaphase o f m e i o s i s i n t h e
o f T h at ch er
by durum c r o s s e s . A, T h a t c h e r X Lakota w i t h I j j j + 13 j j
+ 4 j , ap p r o x . 1250X. B, T h a t c h e r X Langdon w it h I j j j +
15I I + 2I ’ a p p r o x . 1700X. T r i = T r i v a l e n t
28
Table V I I .
M u l t i v a l e n t s o b s e r v e d in p r o g e n i e s o f h e x a p l o i d by
t e t r a p l o i d wheat c r o s s e s .
Cross_______________________________________Chromosome Combination
Thatcher
Thatcher
Thatcher
(Cer e s X
Thatcher
X Lakota
'F2
X Lakota
F2
X Wells
F2
W e l ls ) X Wells BCi
X Lakota
F2
1IV
1 IV
l n/
I 1IV
1IV
+ 12I I
+ 12I I
+ 1 2 TT
+ 12I I
+
12I I
Thatcher
Thatcher
Thatcher
Thatcher
Thatcher
X
X
X
X
X
Langdon
Lakota
Lako ta
Langdon
Lakota
1IV
I IV
1IV
1IV
1IV
+
+
+
+
+
Thatcher
Thatcher
Thatcher
Thatcher
X
X
X
X
Lakota
Langdon
Lakpta
Langdon
F2
F2
F2
F2
F2
F2
F2
F2
F2
(Ceres X W e l ls ) X Wells BCi
Thatcher
Thatcher
Thatcher
Thatcher
(Ceres X
X Langdon
X Langdon
X Langdon
X Lakota
W e l ls ) X Wells
T h a t c h e r X Langdon
T h a t c h e r X Langdon
T h a t c h e r X Lakota
/
F2
F3
F2
F2
BC1
F2
F2
F2
-
12I I
12I I
1^ I I
12I I
12I I
i IV + 12I I
1IV + 12I I
1IV + 13I I
■ 1 IV + 13I I
1I V + 13I I
1IV
1IV
1IV
1I I I
IlII
+
+
+
+
+
14I I
16I I
1I I I
13I I
13I I
. 1I I I + 15I I
1 I I I + !911
2 I I I + 15I I
+
+
+
1T
2I
+
+
+
+
+
2I
3I
Sj + I t e l o
4I
5l
+
+
+
+
6I
7I
3I
3I
+
4I
2I
+
3I
+ 3I
+ 1^ H + 3I
+ 5I
+ 4l
+
+
2I
2I
-
29
-
E x p e r i m e n t I I : Chromosome s e g r e g a t i o n and p r o d u c t i o n o f D d ip l o s o m ic s
from t e t r a s o m i c X durum c r o s s e s .
H e x ap lo id t e t r a s o m i c s ID, 2D, 3D, 4D, 5D, 6D and 7D were each c r o s s e d
t o Dakota and t o Wells durum.
D i f f e r e n c e s between c r o s s e s made t o Dakota
and t h o s e made t o Wells were n o t o b s e r v e d .
For t h i s r e a s o n t h e y w i l l be
discussed to gether.
Heads from random Fp p l a n t s i n each l i n e were c o l l e c t e d i n t h e f i e l d .
Chromosome co m b in at i o n s i n 344 p l a n t s o f 41 Fp l i n e s were d e t e r m in e d
c y t o l o g i c a l l y (Table V I I I ) .
No 1 5 j j p l a n t s were found i n t h e Fp.
p l a n t s w i t h I b j j + I j to 15%% + 4%
A few
were o b s e r v e d i n each o f t h e seven
t e t r a s o m i c by durum c r o s s e s (Table V I I I and F ig u r e 3 ) .
Most F2 p l a n t s examined had each o f t h e 21 p o s s i b l e chromosomes
r e p r e s e n t e d a t l e a s t once (79.6%).
This i s i n c o n t r a s t to Fp p l a n t s o f t h e
T h a t c h e r X durum c r o s s e s i n which o n l y 23.5% o f t h e sampled p l a n t s had each
o f t h e 21 chromosomes r e p r e s e n t e d a t l e a s t once.
An R X C t a b l e ( S t e e l and T o r r i e , I960) was used t o t e s t th e h y p o th ­
e s i s t h a t t h e d i f f e r e n t t e t r a s o m i c X durum c r o s s e s showed s i m i l a r p a t t e r n s
o f chromosome s e g r e g a t i o n i n th e Fg.
The c h i s qu are v a l u e had a p r o b a ­
b i l i t y o f a d e v i a t i o n as l a r g e o r l a r g e r t h a n t h e o b s e r v e d v a l u e o c c u r r ­
ing by chance in from 75% t o 90% o f t h e s a m p l e s .
T h e r e f o r e , i t was
co n cl u d ed t h a t th e p a r t i c u l a r t e t r a s o m i c u se d i n a c r o s s d i d n o t a f f e c t
chromosome s e g r e g a t i o n i n i t s Fg progeny,.
In a d d i t i o n t o t h e chromosome co m b in at i o n s r e p o r t e d i n Table V I I I , a
number o f o t h e r co m b in a ti o n s were a l s o o b s e r v e d (Table IX).
A number o f '
p l a n t s l o s t a t l e a s t one o f th e t e t r a s o m i c chromosomes and, as a r e s u l t ,
-3 0
F igu re
3
—
D ia k in e s is to metaphase I o f m e io sis in F2 p la n ts from
te tr a so m ic X durum c r o s s e s w ith chromosome com binations
approaching 1 5 n . A, 2D X W ells w ith 1 5 n + I j , 1750X.
B, 2D X W ells w ith IS 11 + 1 + 1 t e l o , 1950X. C, 7D X W ells
w ith 15 j j + 3 i , 1300X. D, 6D X durum w ith 15 j j + 4]-,
1300X. Uni = U n iv a le n t, T elo = T elo so m ic.
- 31
Ta bl e V I I I .
F r e q u e n c i e s o f p l a n t s w i t h v a r i o u s chromosome com binations
i n t h e Fg o f c r o s s e s o f t h e t e t r a s o m i c - h e x a p l o i d Chinese
S p r in g X durum.
Chromosome Nos.
IbIl
I b ii + II
lb ll + 2i
I b n + 3i
I b n + 4I
Tbn + bi
I b n + 61
Total of I b n +
16n
i 6n + 11
16I I + 2 I
i 6 n + Si
1 6 n + Al
16ii + 5 i
Total of 16ii +
17n
17I I + 1I
17I I + 2 I
17 I I + 3 I
17 j j + 4 j
T o tal of 1 7 jj +
18l I
1 8 n + 11
1 8 n + 2J
1 8 n + 3j
T o t a l o f 18j j +
20I I
2 0 I I + 1I
T o t a l o f 2 0 j j + X1
2111
ID
0
0
0
2
I
I
I
b
0
0
0
I
2
7
10
0
0
0
0
5
5
0
0
0
6
6
0
0
4 '
4
0
8
8
0
2D
0
0
0
0
I
3
2
6
0
0
I
2
2
8
13
0
Q
0
Q
10
10
0
0
0
6
6
0
0
7
7
0
3
3
0
T o t a l Observed
38
45
^I
Xj
Xj
Xj
19n
i 9 n + 1I
19I I + 2 I
T o t a l o f 19j i + X1
T e t r a s o m i c Hexaploid
3D
4D
5D
, 6D
0
0
0
0
I
0
0
0
I
0
0
0
2
0
0
0 '
2
2
I
I
3
7
I
I
7
5
8
I
13
11
3
16
0
0
0
0
0
0
0
0
I
I
0
0
I
I
0
0
2
2
I ■
0
5
3
10
LO
14
13
4
6
0
0
0
0
0
0
0
0
I
I
0
0
2
4
3
0
12
7
7
15
7
15
20
10
.0
0
0
0
0
0
0
0
3
0
0
0
12
3
5
LZ
12
17
6
5
0
0
0
0
0
0
0
0
4
5
4
Li
4
ii
4
5
0
0 . , 0
0
2
5
I
0
2
I
5
0
I
0
•1
0
40
76
61
29
7D
0
0
0 •
3
I
2
4
10
0
0
0
0
I
8
9
0
0
0
I
16
17
0
0
I
11
0
0
6
6
0
I
I
I
Total
0
I
I
7
9
' 18
28
64
0
0
3
5
10
51
69
0
0
2
10
72
84
0
0
4
52
63
0
0
41
41
0
20
20
3
55
344
LQ
T o t a l Y? ha s p r o b a b i l i t y o f 0 . 9 0 t o 0 .7 5 o f o c c u r r i n g by ch an c e.
32
Tabl e IX
A d d i t i o n a l chromosome co m b in at i o n s o b s er v ed i n Fg p l a n t s o f
t e t ' r a s o m i c C hin es e S p rin g X durum c r o s s e s .
Chromosome
Parental
Chromosome
P a r e n t a l Line_____ Com bin ation _________L i n e _________Com bination
3D
7D
3D
3D
7D
X
X
X
X
X
Dakota
Wells
Dakota
Wells
Wells
14n
14I I
ii
1 4 n +* 21
14I I + 3I
1 4 n + Si
ID
5D
7D
5D
6D
X
X
X
X
X
Dakota H l I + 7 1
Wells i 5 I I + I h e t .
Wells
I l I I + i3 II +
Wells
1I I I + I4 II +
Wells
H l I + 1411 +
ID
3D
3D
3D
7D
X
X
X
X
X
Dakota
Dakota
Dakota
Dakota
Dakota
I 4I j + 4I
+
14I I
5I
I 4H + 5 Is
1 4I I + 3 I
1 4I I + Si
3D
3D
2D
ID
5D
X
X
X
X
X
Dakota I l I I
Dakota 1I H
Dakota I l I I
Wells ■ 1 6 m
Wells i 6 I i
+ I 3H
+
+ 18n
+ 4I
+ 4I
3D
7D
7D
7D
ID
X
X
X
X
X
Wells
Wells.
Wells
Wells
Dakota
14I I
14I I
14I I
14I I
14H
+
+
+
+
+
7D
5D
7D
7D
ID
X
X
X
X
X
Wells
in i
Wells
20I i
Dakota I IV
Wells I 6 I I
Wells
1IV
+ i 7 II +
+
+ I1
+ I 3 TT +
+ I het.
+
+
17I I
5D X Dakota
3D X Dakota
7D X Wells
5I
6I
6 1!
6I + I telo
+ 7t
1 4 TT
+
l 4 I i + 7I
I4J1
7 I1
+
+
+
+
+
+ 5%
5l.
6I
4I
2 T + I telo
4
2l
I telo
I is o
21
I iso
4I
+ 4j
3I
33
had chromosome co m b in at i o n s of 14 j i + ( l t o 7 ) j .
Loss of a t e t r a s o m i c
chromosome could occ ur i f p a i r i n g of t h e chromosomes d e r i v e d from th e
t e t r a s o m e f a i l e d t o o c c u r a t m e io s is in t h e
f a i l u r e would have t o o cc ur i n th e
parent.
Th is p a i r i n g
s i n c e a l l F^ p l a n t s used as p a r e n t s
f o r F2 l i n e s had 1 5 j j + 6j i n most m e i o t i c c e l l s .
Loss of 'a t e t r a s o m i c
chromosome o c c u r r e d in 18 p l a n t s of t h e 377 Fg p l a n t s examined (4.8%).
A number of Fg p l a n t s had m u l t i v a l e n t s a t metaphase I of m e io s is
(Ta bl e I X ) =
S e v e r a l t r i v a l e n t s and q u a d r i v a l e n t s were o b s e r v e d .
I f F^
gametes p a s s e d more t h a n one t e t r a s o m i c chromosome as a r e s u l t of i r ­
r e g u l a r s e g r e g a t i o n o f chromosomes a t anapha se I or anaphase I I of
m e i o s i s , m u l t i v a l e n t s would be e x p e c te d i n some Fg p l a n t s .
I r r e g u l a r d i v i s i o n o f u n i v a l e n t chromosomes coul d a l s o r e s u l t in
m u ltiv a le n t formation.
I.
U n i v a l e n t chromosomes u s u a l l y d i v i d e a t anaphase
O c c a s i o n a l l y t h e y do n o t go t o th e p l a t e a t anaphase I and b o th
c h r o m a t i d s may be i n c l u d e d i n t h e t e l o p h a s e n u c l e u s = At anapha se I I th e
c h r o m a ti d s may a g a i n f a i l t o s e g r e g a t e and, as a r e s u l t , c o u l d be i n c lu d e d
i n t h e same t e l o p h a s e I I n u c l e u s .
For ex am p le , suppose t h a t t h e c h r o ­
m a ti d s o f a u n i v a l e n t chromosome 2D f a i l t o s e p a r a t e a t e i t h e r anaphase I
or anaphase I I .
The r e s u l t i n g m i c r o s p o re n u c l e u s w i l l c o n t a i n two co p ie s
of chromosome 2D and o n ly one copy of each of th e r e s t of t h e chromosomes.
I f i t forms a zygot e w i t h a gamete c o n t a i n i n g a s i n g l e 2D chromosome,
t r i v a l e n t s w i l l occ ur a t metaphase I of m e i o s i s i n t h e r e s u l t i n g p l a n t .
S i m i l a r l y , q u a d r i v a l e n t s co u l d r e s u l t from mating of gametes each c o n t a i n ­
in g two 2D chromosomes.
- 34 M u l t i v a l e n t s coul d a l s o r e s u l t from t r a n s l o c a t i o n s ,, s e c o n d a r y
t r i s o m i c s and t e r t i a r y t r i s o m i c s .
No a t t e m p t was made t o d e t e r m in e th e
o r i g i n o f t h e d i f f e r e n t m u l t i v a l e n t s o b s e r v e d in t h i s s t u d y .
One i n t e r e s t i n g p l a n t w i t h I l 11 + 7 ^ was ob se rv ed (Tab le IX).
D e s y n a p s i s was c o n s i d e r e d as one p o s s i b l e e x p l a n a t i o n , b u t n e a r l y a l l
c e l l s from t h i s p l a n t showed I l j j + 7 j a l t h o u g h a few had 10%% + 9j .
T h e r e f o r e , t h i s p l a n t had p r o b a b l y l o s t a t l e a s t t h r e e chromosomes from
t h e A and, o r B genome and hdmoeologous chromosomes from t h e D genome were
a b l e t o compensate f o r t h e s e l o s s e s .
S e v e r a l s eed s were prod uced by t h i s
p l a n t and Fg pr ogeny had 7, 3, I , I , I , and I p l a n t w i t h chromosome combi­
n a t i o n s o f 14%%, 14%% + 1%,14%% + 2%, 14%% + 3%, I %%% + 13%% and
1%%% + 13%% + 1%, r e s p e c t i v e l y .
,
■
S in c e t h e p r im a r y o b j e c t i v e o f t h i s s t u d y was to o b t a i n D d ip l o s o m ic s
w i t h 15%%, s e l e c t i o n was c o n t i n u e d i n t h e Fg.
P l a n t s w i t h more t h a n 15%%
would n o t be e x p e c t e d t o r e v e r t t o 15%% u n l e s s p a i r i n g o f some homologous
chromosomes was i r r e g u l a r . ' The b e s t chance f o r f i n d i n g 15%% p l a n t s sh oul d
be i n t h e pr oge ny o f Fg p l a n t s w it h 15%% + (I t o 5)%.
The Fg s ee ds from i n d i v i d u a l Fg p l a n t s were seeded i n t h e greenho us e
i n t h e autumn o f 1966 and w i n t e r o f 1966-67.
Seeds from a few Fg p l a n t s
w i t h chromosome co m b in at i o n s o f from 14%% + 1% t o 14%% + 5% were a l s o
planted.
The Fg f a m i l y o f e ac h Fg p l a n t
t e r m i n e i t s chromosome complement.
served,
(Table X).
was examined c y t o l o g i c a l l y t o d e ­
S e v e r a l p l a n t s w it h 15%% were ob­
Most 15%% p l a n t s o c c u r r e d in th e pr ogeny o f Fg p l a n t s
)
)
)
'
- 35
w it h 1 5 j j + ( I t o 4 ) j „
Only one 1 5 j j p l a n t was o bs erv ed i n 119 progeny
from ?2 p l a n t s w i t h 15 j j t Sj=
A 1 5 j j p l a n t was a l s o found among th e
progeny of an Fg p l a n t w i t h 14 j j + 5j-„
The r e s u l t s s u g g e s t t h a t s e l e c t i o n
f o r 1 5 j j was most e f f i c i e n t in t h e progeny of Fg p l a n t s w i t h
1 5 n + ( l to 4 ) j 0
P l a n t s w it h chromosome co m b in at i o n s which in c l u d e d l e s s th a n the
maximum p o s s i b l e 21 chromosomes would n o t be ex p ec te d t o produce progeny
w i t h a l l 21 chromosomes r e p r e s e n t e d a t l e a s t on ce.
For ex am p le 9 a p l a n t
w i t h 1 5 j j + 3-j- has 18 d i f f e r e n t chromosomes r e p r e s e n t e d one or more times =
A p l a n t w it h t h i s chromosome c om b in at io n would n o t be e x p e c t e d t o produce
progeny w i t h chromosome c o m b in a ti o n s such as 1 5 j j + 4 j , I b j j + S j 5
1 7 jj + 2j 5 e t c .
In g e n e r a l 5 t h e r e s u l t s were i n agreement w i t h e x p e c t ­
a t i o n , b u t t h e r e were e x c e p t i o n s .
P l a n t 11-2 from t h e c r o s s 3D X Wells
w i t h 1 4 j j + 5 j produced one p l a n t w it h 15 j j + 5j=
A p la n t with th i s
chromosome co m b in at i o n co ul d occ ur i n t h e progeny of a 1 4 j j + 5 j p l a n t
e i t h e r by o u t c r o s s i n g or by d u p l i c a t i o n of a chromosome a l r e a d y p r e s e n t .
O u t c r o s s i n g 'was t h e most l i k e l y e x p l a n a t i o n .
P l a n t 13-10 from t h e c r o s s t e t r a s o m i c 3D X Dakota was r e p o r t e d to
have t h e chromosome c o m b in a ti o n 1 5 j j + 4 j .
However5 f i v e Fg progeny of
t h i s p l a n t had a t o t a l of 20 chromosomes r e p r e s e n t e d a t l e a s t once .
The
t r u e chromosome co m b in at i o n of t h i s Fg p l a n t was p r o b a b l y 1 5 j j + 5 j .
P l a n t 22 -7 from t h e c r o s s t e t r a s o m i c 4D X Wells was b e l i e v e d t o have
15jj + 5 j.
The progeny of t h i s p l a n t i n c l u d e d two p l a n t s w i t h a l l 21
p o s s i b l e chromosomes r e p r e s e n t e d a t l e a s t on ce , so t h e c o r r e c t chromosome
)
)
)
)
co m b in a ti o n
i n p l a n t 2 2 - 7 was p r o b a b l y 1 5 j j + 6j or I 6j j + 5 j .
36 ~
T a b l e X.
F r e q u e n c i e s o f v a r i o u s chromosome c o m b i n a t i o n s i n t h e Fg p r o g e ­
n i e s o f T h a t c h e r X durum and t e t r a s o m i c C h i n e s e S p r i n g X
durum c r o s s e s „
Progeny
of
Chromosome
Combination
14n
14I I + I l
1 4 n + 2j
14I I + 3 I
14 i i + 4 I
14I I + 5 I
14 i i + 6%
1 4 n + T1
15u
I 5I I + I l
15I I + 2 I
1 5 n + S1
1 5 n + 4j
1 5 n + S1
I S j t + -6 t
1611V
16I l + 1I
16I l + 2 I
16I l + 3I
1 6 1 1 + 4I
16I l + '5 I
I 7I l
IT n + I1
17H + 2 I
I 7I i + 3 I
I T 1J + 4 j
18ll
18n + I1
18I I + 2 I
1811 + Si
19 i i
■
1 9 n + 11
19 j i + 2 j
20 I I
20I I + 1I
21l l
Other
Totals
Tcr x durum &
CoS, x durum
14 j i + ( l t o 5 ) i
■ 109
ST
10
8
3
2
I
0
I
0
3
T
3
I
0
0
0
I
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
188
C hin es e S p r „
x durum
15j j + ( I t o 4 ) i
0
I
I
0
2
2
■ I
I
• T
T
5
11
IT
I
0
0
0
5
8
2
0
0
I
10
2
0
I
0
I
0
0 ■
I
0
0
0
0
I
88
Chine se S p r .
x durum
I S 11 + S1
0
0
0
0
I
2
I
I
I
T
3
9
T
9
I
0
I
T
14
20
0
0
0
6
15
0
I
4
6
I
0
2
0
2
I
0
0
119
'
Total
109
38
11
8
6
6 .
3
2
9
14
'11
27
27
11
I
0
I
13
24
22
0
0
I
16
IT
0
I
4
T
I
0
3
0
2
I
0
5
395
37
There .was 3' g e n e r a l t e n d e n c y f o r p l a n t s w it h chromosome co m bin ati on s
a p p r o a c h i n g 15 j j t o be low i n f e r t i l i t y and v i g o r .
The v i g o r , f e r t i l i t y
and g r o s s morphology of p l a n t s i n s e v e r a l Fg f a m i l i e s were i n v e s t i g a t e d .
The r e s u l t s a r e r e p o r t e d i n T ab le s XI t h r o u g h XIX.
A p l a n t w i t h 15 j j was o bs erv ed among t h e seven progeny of Fg p l a n t
2 -1 3 from t h e c r o s s t e t r a s o m i c ID X Wells ( T ab l e X I ) .
presu mably d i p l o s o m i c f o r chromosome ID.
heads r e s e m b l i n g t h o s e of common w hea t.
i n m a t u r i t y and c o m p l e t e l y male s t e r i l e .
Thi s p l a n t was
The p l a n t was b e a r d e d , w it h s ma ll
Thi s p l a n t was v i g o r o u s , v e r y l a t e
The s t e r i l i t y was l i m i t e d t o th e
male s i n c e p o l l i n a t i o n w i t h h e x a p l o i d p o l l e n from P . I . 178383 produced 10
s ee d from 25 f l o r e t s .
Three of t h e s i x s i s t e r p l a n t s had chromosome
co m b in a ti o n s of l e s s t h a n 15 j j - + 4 j .
These t h r e e p l a n t s were a l s o s t e r i l e .
The t h r e e r e m a in in g p l a n t s w i t h chromosome c o m b in at io n s of 1 5 j j + 4 j or
more were p a r t i a l l y f e r t i l e .
The Fg f a m i l y of p l a n t 29-3 from t h e c r o s s t e t r a s o m i c 5D X Wells
produced one 15 j j p l a n t among seven progeny (Ta b le X I I ) .
p artially fe rtile .
Thi s p l a n t was
Good b i v a l e n t s were formed a t metaphase I o f m ei o sis
and t h e chromosomes s e g r e g a t e d r e g u l a r l y a t anaphase I .
Of 37 c e l l s
examined, 12 had 15 r i n g b i v a l e n t s , 10 had 14 r i n g b i v a l e n t s p l u s I r o d ,
4 had 13 r i n g b i v a l e n t s p l u s 2 rods and I had 12 r i n g b i v a l e n t s p lu s 3
rods.
plants.
S i n c e p a i r i n g was r e g u l a r , a l l pr ogeny would be e x p e c t e d t o be I b j j
Eleven F4 p l a n t s were grown i n t h e greenhouse d u r i n g t h e summer
of 1967 and a l l had 15%%.
l e a f was s h o r t and w id e.
The p l a n t s were s h o r t (25 t o 35 cm).
The f l a g
Heads res embled a sem ic lub typ e s i m i l a r to
C hin es e S p r i n g b u t w i t h o u t t h e beaked, lemma of Chinese S p r i n g .
F ertility
-
of t h e s e p l a n t s was low.
38
-
The a n t h e r s were s m a l l , th e y o f t e n a b o r t e d and
when t h e y d i d n o t a b o r t , t h e y f r e q u e n t l y f a i l e d t o d e h i s c e .
They were
m a i n t a i n e d by growing un der good growth c o n d i t i o n s and by f o r c i n g
d e h i s c e n c e of t h e a n t h e r w i t h a p a i r of t w e e z e r s .
presumably' c a r r i e s chromosome 5D.
This D d i p l o s o m i c l i n e
I d e n t i t y of th e e x t r a chromosome p a i r
i s b e i n g checked by c r o s s i n g t o a s e t of d i t e l o s o m i c chromosome -lines f o r
t h e D genome,
I t e l o or
P r o g e n i e s of such
c r o s s e s s h o u ld form e i t h e r 1 5 ^ + 5^. +
14 j j + I h e t e r o m o r p h i c b i v a l e n t + 6^.
The l a t t e r ca s e would
c o n f i r m t h e i d e n t i t y of t h e e x t r a chromosome p a i r in th e d i p l o s o m i c .
Two 15%% D -d ip lo s o m ic p l a n t s were found i n th e progeny of Fg p l a n t
17-.2 from a t e t r a s o m i c 4D by Lakota c r o s s .
a l l c h a r a c t e r i s t i c s ( T ab l e X I I I ) .
4a and 4b) and f a i r f e r t i l i t y .
The two p l a n t s were s i m i l a r in
These p l a n t s have a cl u b head ( F ig u r e
The s eed s a r e somewhat f l a t t e n e d because
of t h e c l o s e crowding of f l o r e t s and s p i k l e t s i n th e he ad .
P a i r i n g a t metaphase I of m e io s is was good.
Of 28 c e l l s of p l a n t
17 -2 -1 0 which were examined i n d e t a i l , 4 had 15 r i n g b i v a l e n t s , 4 had 14
r i n g s and
I rod b i v a l e n t , 12 had 13 r i n g s and 2 rod b i v a l e n t s , 4 had 12
r i n g s and
3 rod b i v a l e n t s , 2 had 11 r i n g s and 4rod b i v a l e n t s and 2 had 9
r i n g s and 6 ro d b i v a l e n t s .
cells.
No u n i v a l e n t s were o b s e r v e d i n any of the
These p l a n t s would be ex p ec te d t o produce progeny w i t h 15%%.
A ll
14 F^ p l a n t s i n t h e progeny o f p l a n t 1 7 - 2 - 1 0 and a l l 6 F^ p l a n t s in the
progeny of p l a n t 1 7 - 2 - 6 had 15]-%.
These two p l a n t s and t h e i r progeny ar e
p r o b a b l y d i p l o s o m i c f o r chromosome 4D from Chine se S p r i n g .
They ar e b e i n g
c r o s s e d t o a s e t of D genome d i t e l o s o m i c l i n e s in o r d e r t o p o s i t i v e l y
i d e n t i f y t h e e x t r a chromosome p a i r .
- 39 T a b l e X I.
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s w i t h
v a r i o u s chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f Fg p l a n t
2 - 1 3 from t h e c r o s s t e t r a s o m i c ID X Wells w i t h 1 5 j j + 4 j .
F3 P l a n t
No.
Chromosome
No.
2 - 13 - 15
15n
79
2-13- 4
15u + Il
2-13- 3
H ei g h t
CM.
T illers
No.
F ertility
% Of Check
Awns
Type
Head
Type
7
S terile-/
Awned
Vulgare
86
9
S terile
Awned
■ Vulgare
1 5 n + 2l
70
7
S terile
Awhed
Vulgare
2-13-14
15I I + 3I
112
31
S terile
Awned
Vulgare
2-13- 5
15I I + 4 I
87
10
15
Ti p awn
Vulgare
2-13- 9
16I I + 2 l
97
7
70
Awned
Vulgare
2 - 1 3 - 6^ /
19n + Ii +
frag,
62
8
20
Awned
Vulgare
.
I/
Note 2 - 1 3 - 1 5 was male s t e r i l e b u t female f e r t i l e as shown by s u c c e s s ­
f u l c r o s s i n g t o normal h e x a p l o i d , P d . 178383.
2/
2 - 1 3 - 6 i s p r o b a b l y th e r e s u l t of an Fg o u t c r o s s =
Table X II,
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s w i t h
v a r i o u s chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f Fg p l a n t
2 9 - 3 from t h e c r o s s t e t r a s o m i c 5D X Well s w i t h 1 5 j j + 4 j ,
F3 P l a n t
No.
Chromosome . H e ig h t
No „
CM,
29- 3- 9
15I I
50
29- 3- I
I 5I I + i i
Died
29- 3- 7
15I I + i i
32
3
29- 3-16
15I I + 4 I ■
53
29- 3- 4
I 6I I + 2 l
Died
29- 3-13
16I I + 3I
29- 3-14
16I I + 3I
T illers
No,
F ertility
% Of Check
Awns
Type
Head
Type
Awnless
Club
S terile
Awned
Vulgare
5
S terile
Awnless
Vulgare
72
5
30
Ti p awned
Vulgare
71
4
2
Ti p awned
Vulgare
6
' 25
41
Table X I I l „
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s w i t h
v a r i o u s chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f Fg p l a n t
17^2 from t h e c r o s s t e t r a s o m i c 40 X La ko ta w i t h 1 5 j j + 4 j „
Fo P l a n t • Chromosome
No.
No.
H ei g h t
CM.
T illers
No.
F ertility
% Of Check
Awns
Type
Head
Type
17 -2 - 6
15I I
85
■ 7
24
Awned
Club
1 7- 2 - 10
15n
81
9
20
Awned
Club
1 7- 2 - 4
14I I + 2 I
105
8
36
Awned
Club
17- 2- 8
15n
H- 4 I
20
2 .
S terile
1 7 - 2- 20
15n + ii
121
23
44
Awnless
Abberent
Club
17-2-21
14I I + i
hetero + 2i
30
7
5
T i p awned
Abberent
Club
—42 —
Figure
4
Fg p l a n t s 1 7 - 2 - 6 and 17 -2 -1 0 with 1 5 j j o f chromosomes.
Note t h e compact heads and s i m i l a r i t y i n morphology.
—43 —
Figure
5
Metaphase I o f m e i o s i s (A) and anaphase I o f m e i o s i s (B) i n
F4 p l a n t 1 7 - 2 - 1 0 - 4 , b ot h 1400X. Note good p a i r i n g a t meta­
phas e and r e g u l a r s e g r e g a t i o n a t a n ap h a se .
44
The F2 p l a n t 18-1 from t e t r a s o m i c 4D X Wells a l s o produ ced one p l a n t
w i t h 15 j j .
This p l a n t was s i m i l a r t o 1 7 - 2 - 1 0 and 1 7 -2 -6 i n v i g o r and
morphology, b u t proved t o be s t e r i l e .
The p l a n t 3 3 - 9 • from t h e c r o s s 6D by Wells produced one 1 5 j j p l a n t
(Ta bl e XIV) .
S e v e r a l o t h e r p l a n t s w i t h numbers ap p r o a c h in g 1 5 j j were a l s o
p r o d u c e d , b u t most of t h e s e p l a n t s f a i l e d t o s e t s e e d .
f a m i l y were t y p i c a l l y s h o r t w i t h an a w n l e s s , cl u b he ad .
f l a g l e a f was u s u a l l y s h o r t and wide.
P l a n t s in t h i s
The t e r m i n a l or
These c h a r a c t e r i s t i c s a r e t y p i c a l
of most p l a n t s w i t h 6D as an e x t r a chromosome p a i r .
Family 31-4 from th e
c r o s s 6D X durum (Tab le XV) was s i m i l a r i n a l l r e s p e c t s t o f a m i l y 33- 9.
Plant
4- 3 from t h e c r o s s t e t r a s o m i c ID by Dakota produced t h r e e Fg
p l a n t s , one of which had t h e c o m bi na ti o n 15 j j .
s h o r t , l a c k i n g i n v i g o r and s t e r i l e .
A l l t h r e e p l a n t s were
Whether t h e u n b al an ce caused by
chromosome ID always r e s u l t s in s t e r i l i t y c a n n o t be d e t e r m in e d on the
b a s i s of a s i n g l e o b s e r v a t i o n .
One o t h e r c r o s s produced one p l a n t w i t h 1 5 j j and one p l a n t w it h 14 j j
p l u s one h e t e r o m o r p h i c b i v a l e n t .
and 1 2 -6 , r e s p e c t i v e l y .
These p l a n t s app eared i n f a m i l i e s 10-5
Both f a m i l i e s were l a r g e l y d e s y n a p t i c f o r th e
e x t r a p a i r of chromosomes ( T ab l e XVI) .
The p a r e n t s of l i n e s 10-5 and
12-6 b o t h had 1 4 j j + 5 j and b o t h o c c a s i o n a l l y had 15 j j + 3 j .
Evidently
t h e r e was some homology between two of t h e D genome chromosomes.
Whether
t h i s was t h e r e s u l t o f a t r a n s l o c a t i o n , or t r u e homology or some o t h e r
f a c t o r i s unknown.
A number of a d d i t i o n a l Fg f a m i l i e s had f e r t i l e p l a n t s w i t h chromosome
numbers a p p r o a c h i n g 1 5 u „
The Fg p l a n t 9-11 from t h e c r o s s t e t r a s o m i c 2D
- 45 T a b l e XIV„
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s w i t h
v a r i o u s chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f
plant
3 3 - 9 from t h e c r o s s t e t r a s o m i c 6D X durum w i t h I S j j + 5 j „
Fq P l a n t
No.
Chromosome
No.
H ei g h t
CM
33-9-5
15%%
'
3 3 -9 -6
T illers
No.
F ertility
% Of Check
Awns
Type
Head
Type
65
.9
S terile
Awnless
Club
15I I + 1I
60
10
Sterile
Awned
Club
33-9-3
15I I + 3%
43
5
S terile
Awnless
Club
3 3 -9 -4
15I I + 4 I
84
13
I
Awnless
Club
3 3 -9 -1
16I I + 2 I
25
3
S terile
Awnless
Club
16I I + 3I
21
3
S terile
Awned
Club
33-9-2
Tabl e XV.
V ig o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s of p l a n t s w ith
v a r i o u s chromosome c o m bi n at io n s i n t h e progeny o f Fg p l a n t
31 -4 from t h e c r o s s t e t r a s o m i c 6D X durum w it h 15%% + 4%.
Fg P l a n t
No.
Chromosome
No. .
H ei g h t
CM
T illers
No.
F ertility
% Qf Check
Awns
Type
Head
Type
31- 4- 1
15I I + 2 I
63
3
I
Awnless
Club
31-4-6
18I I
32
3
S terile
Awnless
Abnormal
- 46 -
Table XVI.
Frequency o f chromosome c o m b in a ti o n s i n two Fg f a m i l i e s
from t h e c r o s s t e t r a s o m i c 3D X W e l l s .
Number Observed
Chromosome
Combination
14I I
14I I + 1I
1 4 n + 2j
14I I
14I I
14I I
14 j j
14I I
+
+
+
+
+
3I
4I
5I
6j
7I
15I I
15I I
15I I
15I I
15I I
15I I
15n
+
+
+
+
+
+
1I
2I
3I
4I
5I
6j
!bn
16I I + 1I
16I I + 2 I
16 j j + 3 j
O th er
Family
10-5
4
4
3
2
0
0
I
0
I 4II + I hetero
0
0
0
' 0
I
0
0
0
0
I
1 I I I + 13I I + 1I
Family
12-6
•-
.
17
7
4
0
0
0'
. 0
■0 ■
I
0
0
0
0
0
■0
0
0
0
0
0
47
by Wells produced s e v e r a l p l a n t s w it h chromosome co m b in at i o n s ap p r o a c h in g
15 j j ( T ab l e XVI I) . A l l p l a n t s w i t h chromosome numbers a p p r o a c h i n g IS^-j-?
( I b j j + 1 | to
+ 4.J.)
were l a r g e l y s t e r i l e .
They were a l s o s h o r t e r
and l e s s v i g o r o u s th a n o t h e r p l a n t s in t h e f a m i l y .
The F2 p l a n t 13-10 from t h e c r o s s t e t r a s o m i c 3D by Dakota produced
two p l a n t s w it h chromosome c o m bi n at io ns a p p r o a c h i n g 15 j j ( T ab l e XVIIl)'.
Both o f t h e s e p l a n t s were p a r t i a l l y f e r t i l e .
However, t h e y l a c k e d v i g o r .
The most i n t e r e s t i n g a s p e c t of t h i s f a m i l y was th e f r e q u e n t p r e s e n c e of
h e t e r o m o r p h i c b i v a l e n t s formed from one normal and one homologous
t e l o s o m i c chromosome.
the progeny.
The h e t e r o m o r p h i c b i v a l e n t was p r e s e n t i n h a l f of
P l a n t 13- 10- 5 had one t r i v a l e n t p lu s 18 b i v a l e n t s .
In t h i s
ca s e t h e t r i v a l e n t had been formed from two normal and one t e l o s o m i c
chromosome.
The F2 p l a n t 35-17 from t h e c r o s s t e t r a s o m i c 7D by Dakota produced
one p l a n t w i t h t h e chromosome c om b in at io n 1 5 j j + 4 j (Ta b le XIX).
Thi s p l a n t had a h ig h r a t e o f d e s y n a p s i s a t metaphase I .
w i t h 14 j j + ( I, t o 7 ) j were produced as a r e s u l t .
p a r t i a l l y f e r t i l e and r e l a t i v e l y v i g o r o u s .
S e v e r a l progeny
A ll p l a n t s were a t l e a s t
P l a n t 3 5 - 17 -1 6 w i t h 1 5 j j + 4 j
r e g u l a r l y formed 15%% a t metaphase I o f m e i o s i a .
The F4 progeny of t h i s
p l a n t s h o u l d i n c l u d e some 15%% p l a n t s .
A number of a d d i t i o n a l Fg f a m i l i e s were i n v e s t i g a t e d and t h e r e s u l t s
were s i m i l a r t o th o s e f o r t h e f a m i l i e s d e s c r i b e d p r e v i o u s l y .
The t e t r a s o m i c h e x a p l o i d s were used i n c r o s s e s w i t h durum i n o r d e r t o
i n c r e a s e t h e p r o b a b i l i t y o f o b t a i n i n g 15%j p l a n t s and t o g iv e some a s 9pr an ce t h a t t h e chromosome i n v o l v e d was t h e same as th e t e t r a s o m i c
)
)
I
48
T a b l e X V II .
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f v a r i o u s
chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f Fg p l a n t 9-11 from
t h e c r o s s t e t r a s o m i c 2D X W e lls w i t h IS^p + 5 j .
Chromosome
No.
9 -1 1 -2 2
9 -1 1 -2 7
I 5 I I . + 1I
15n + Ij + I
telo
1 5 n + S1
I Si I + Si
I5II + s i
+14I I
+ 3t
15I I + 4 t
15I I + 5 j
15I I + 5 j
I 5II + 5I
15I I + 5 j
15I I + 5 I
15I I + 5 I '
-I 5 H + s i
-16I I + 2 i
16I I + S i
16I I + 3 j
I 6 n + Si
16I I- + 4 1
16I I + 4 j
1 6 n + 41
1 6 n + 41
+. 2 1 - .
17I t + 2 I
1I i i +17I I
+
2j
20n
M
M
M
9 -1 1 - 8
r•— I
9 -1 1 - 4
9 -1 1 - I
9 -1 1 - 7
9 -1 1 -1 0
9 -1 1 -1 2
9 -1 1 -1 4
9 -1 1 -1 9
9 -1 1 -2 9
9 -1 1 -3 0
9 -1 1 -1 5
9 -1 1 -1 7
9 -1 1 -1 8
9 -1 1 - 5
9 -1 1 -1 3
9 -1 1 -2 1
9 -1 1 -2 6
9 -1 1 - 9
9 -1 1 -3 1
9 -1 1 -2 4
f—i
9 -1 1 -2 0
9 -1 1 -2 3
9 -1 1 -2 8
9 -1 1 -2 5
1—f
■—I
Fg P l a n t
No.
H ei g h t
CM.
T illers
No.
78
37
10
2'
50
58
66
71
F ertility
Awns
% Of Check . Type
Head
Type
S terile
■S t e r i l e
Awned
Tip awned
Vulgare
Vulgare
4
6 ■
6
10
S terile
0 .5
S terile
S terile
Awned
Ti p awned
Tip awned
Awned
Vulgare
Vulgare
Vulgare
Vulgare
82
85
95
92
74
94
88
100
70
75
88
63
72
63
74
66
53
73
72
11
8
10
11
9
17
8
17
9
6
8
8
8
4
12
4
6
7
5
2
33
6
9
19
24
23
38
S terile
11
26
S terile
14
0 .5
27
6
2
10
S terile
Awned
Awned
Tip awned
Tip awned
Awned
Awned
Awned
T i p awned
Awned
S h o r t awn
S h o r t awn
S h o r t awn
S h o r t awn
T i p awn
Ti p awn
Awned
Awnless
Awned
S h o r t awn
Vulgare
Vulgare
Vulgare _
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
Small club
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
Vulgare
78
9
70
Ti p awn
Vulgare
- 49
T a b l e XVIIIo V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s w i t h
.
• v a r i o u s chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f Fg p l a n t
13 -1 0 from t h e c r o s s t e t r a s o m i c 3D X Dakota w i t h
1 5 n + 4-1 + 1 t e l O o
Fs P l a n t
No o
Chromosome
No,
H e ig h t T i l l e r s
CM,
No,
13-10- I
15I I + 3 I
- -57
4
13- 10- 7
I S 11 + 4 j
+ I telo
. 61
9
13 - 10- 12
!S n + I ■
het e.ro + 2 l
36
5
13- 10- 4
!S n + I
hetero + 4I
71
13 - 10- 10
15I I + 1
hetero + 4I
13-10-13
F ertility
% of Check
•5
Awns
Type
Head
Type
Awnless
Semiclub
■Semiclub
"
28
Awned
S terile
Awnless
Vulgare
10
65
Awned
Semiclub
' 64
11
30
Tip awn
Semiclub
16I I + 3 I
76
9
5
Awned
Vulgare
13- 10- 6
16n + I
hetero + 3I
56
18
20
Tip awn
Semiclub
13-10- 9
1IV +14I I +
I h e t e r o + :v
12
.12 .
Tip awn
Semiclub’ '
56.
13-10- 2
17I I + 2 I
61
5
30
Tip awn
Semiclub
13-10- .3
I 7I I + 3 I
64
11
45
Awned
Semiclub
13-10- 8
I 8 I I + - 1I - +
1 telo
SI
7
20
Tip awn
Vulgare
13- 10- 5
1I I I +18I I
46
8
17
Ti p awn
■Semiclub
■
.
.
:
50
T a b l e XIX.
V i g o r , f e r t i l i t y and o t h e r c h a r a c t e r i s t i c s o f p l a n t s w i t h
v a r i o u s chromosome c o m b i n a t i o n s i n t h e p r o g e n y o f Fg p l a n t
3 5 - 1 7 from t h e c r o s s t e t r a s o m i c 7D X Lak ot a w i t h 1 5 j j + 5 j .
Fg P l a n t
No.
Chromosome
No.
35 - 1 7- 9
14I I + 4 I
75
4
3 5- 1 7 - 3
14I I + Si
101
3 5- 1 7 - 7
14I I + 5 I
100
3 5- 1 7 -1 5
14I I + 6 j
114
3 5- 1 7 - 2
14I I + 6I..
35 - 1 7 - 16
Height T i l l e r s
CM.
No.
Awns
Tvne
Head
Tvne
25
Awnless
Vulgare
17
40
Tip awn '
Vulgare
10
70
Awnless
Vulgare
10
61
Tip awn
Vulgare
108
7
40
Ti p awn
Vulgare .
15I I + 4 i
120
31
20
Awnless
Club
3 5- 1 7 - I
15I I + Si
92
3
• 13
Ti p awn
Vulgare
35 - 1 7 - 18
15I I . + Si
87
5
6
Tip awn
Vulgare
35 - 1 7 - 10
I 6H + 4 I
103
11
70
Awnless
Vulgare
35 - 17- 17
16I I + 4 j
100
13
32
Awnless
Vulgare
35 - 17- 13
16I I + 4 i
120
16
65
Awned
Vulgare
35 - 1 7 - 12
I 7I I + 3I
. 102
12
6
Awnless
Vulgare
35 - 1 7 - 14
18H + 2 l
80
7
40
Awned
Vulgare
3 5- 1 7 - 6
'
I 7I I + I
hetero + 2j
106
10
87
Awnless
Club
'
F ertility
% of Check
51
chromosome p r e s e n t i n t h e o r i g i n a l c r o s s .
I f th i s hypothesis is c o rre c t,
15 j j p l a n t s - were found f o r a l l D genome chromosomes w ith t h e e x c e p t i o n
of 2D and 7D.
There were t h r e e p l a n t s w i t h 4D d i p l o s o m i c , two p l a n t s w it h
3D d i p l o s o m i c , and one d i p l o s o m i c f o r each o f t h e r e m a in in g D genome
chromosomes.
Of t h e s e e i g h t D d i p l o s o m i c s o n ly t h r e e produced s e e d .
o f th e f e r t i l e p l a n t s were 4D. d i p l o s o m i c s i n th e f a m i ly o f 1 7 - 2 .
The
o t h e r was-a 5D d i p l o s o m i c i n t h e f a m i ly o f Fg p l a n t 2 9 - 3 .
F a i l u r e t o i s o l a t e f e r t i l e p l a n t s o,f a l l of th e p o s s i b l e D
d i p l o s o m i c s may be due t o l i m i t e d p o p u l a t i o n s i z e s , or t o s t e r i l i t y
r e s u l t i n g from chromosome u n b a l a n c e ,
•
Two
DISCUSSION
E xp er im en t I
S e g r e g a t i o n o f D Genome Chromosomes i n T h a t c h e r X Durum Cr os se s
The chromosome co m b in at i o n s o c c u r r i n g in th e Fg p l a n t s o f h e x a p l o i d X
t e t r a p l o i d ' wheat c r o s s e s have been i n v e s t i g a t e d by s e v e r a l w o r k e r s .. The
most e x t e n s i v e i n v e s t i g a t i o n s a r e t h o s e o f K ih ara and c o - w o r k e r s „
(1924) examined l a r g e numbers o f
Kihara
p l a n t s from th e c r o s s I . ae sti v u m
( 2 f j j ) X I . t u r g i d u m (1 4 j j ) and d e t e r m in e d chromosome numbers c y t o l o gically.
He r e p o r t e d an e x c e s s o f p l a n t s w i t h 1 4 jj and o f p l a n t s w i t h a l l
21' chromosomes r e p r e s e n t e d a t l e a s t on ce .
J e n k i n s and Thompson (1930)
examined a s m a l l sample o f Fg p l a n t s from a I . ae s ti v u m X I . durum cr os s
and c on cl ud ed t h a t t h e i r r e s u l t s were i n agreement w i t h t h o s e o f K i h a r a .
The r e s u l t s o b t a i n e d i n t h e p r e s e n t s t u d y were s i m i l a r t o t h e above.
U n i v a l e n t s were e x p e c t e d t o s e g r e g a t e a t random d u r i n g m e i o s i s i n F^
p la n ts of pentaploid hybrids.
The f a i l u r e t o o b t a i n t h e e x p e c te d number
o f p l a n t s w i t h v a r i q u s chromosome co m b in at i o n s in t h e Fg g e n e r a t i o n le d
K ih a r a and Matsumura (1940) t o i n v e s t i g a t e t h e number o f u n i v a l e n t s pas se d
t h r o u g h F]_ g a m e te s .
They b a c k - c r o s s e d t h e p e n t a p l o i d h y b r i d t o each o f
t h e p a r e n t s and d e t e r m i n e d t h e number o f u n i v a l e n t s i n BC^ p r o g e n i e s .
Thompson and Cameron (1928) a l s o used t h i s method to o b t a i n e s t i m a t e s o f
t h e f r e q u e n c y w it h which u n i v a l e n t s a r e p a s s e d th r o u g h F^ g a m e t e s „
The
d a t a o f Thompson and Cameron were compared t o d a t a o b t a i n e d i n t h e s t u d y
reported h e r e .
A c h i s q u a r e comparison i n d i c a t e d t h a t t h e r e was a p r o b ab ­
i l i t y o f 5% t o 10% t h a t t h e two s e t s o f d a t a were homologous.
Two
p o s s i b l e e x p l a n a t i o n s f o r t h e d i f f e r e n c e s i n t h e two s e t s o f d a t a a r e :
- 53 (1)
D i f f e r e n t g e n e t i c m a t e r i a l s were u s ed .
(2)
There were n o t enough o b s e r v a t i o n s in e i t h e r s t u d y to
obtain the c o r r e c t frequency.
The f r e q u e n c i e s of v a r i o u s chromosome c o m b in at io n s o b s e r v e d in Fg
p l a n t s from t h e p r e s e n t s t u d y was compared w i t h th e f r e q u e n c i e s of chromo­
some c o m b in a ti o n s e x p e c t e d on t h e b a s i s of t h e number o f u n i v a l e n t s pas se d
th r o u g h female gametes i n a (Cere s X W el ls ) X Wells t e s t c r o s s .
According
t o ' L i l i e n f e l d ( 1 9 5 1 ) , K ih ar a was u na b le t o e x p l a i n th e o b t a i n e d r a t i o s on
t h e b a s i s of random u n i v a l e n t s e g r e g a t i o n .
Some of th e c a u s e s of th e
d i s c r e p a n c i e s were:
( 1)
E l i m i n a t i o n of u n i v a l e n t s was i m p o r t a n t .
(2)
The u n i v a l e n t s te n d t o be d i s t r i b u t e d i n bunches r a t h e r
th a n s e p a r a t e l y .
(3)
There was s t r o n g c o m p e t i t i o n between p o l l e n g r a i n s , t h o s e
w it h 14 and 21 chromosomes were t h e b e s t c o m p e t i t o r s .
(4)
S e l e c t i v e f e r t i l i z a t i o n d i d n o t occ ur i f s u f f i c i e n t p o l l e n
was s u p p l i e d .
K ih a r a was a b l e t o e x p l a i n th e f r e q u e n c i e s of v a r i o u s chromosome
co m b in a ti o n s i n Fg on t h e b a s i s of th e number of u n i v a l e n t s p a s s e d th r ou g h
male and female gametes as d et e r m in e d by b a c k c r o s s e s of p e n t a p l o i d h y b r i d s
t o t h e i r p a r e n t s ( L i l i e n f e l d 1951).
The poor f i t of t h e r a t i o s c a l c u l a t e d
on t h i s b a s i s in th e p r e s e n t s t u d y may have been due t o one o r more of
the following f a c t o r s ;
- 54
( 1)
U n i v a l e n t s may n o t be p a s s e d th r o u g h male gametes w ith
t h e same f r e q u e n c i e s as t h r o u g h female g am ete s.
(2)
I n s u f f i c i e n t p l a n t s were examined i n th e Fg p r o g e n i e s of
T h a t c h e r X durum c r o s s e s t o g iv e a c c u r a t e s e g r e g a t i o n
ratios.
(3)
I n s u f f i c i e n t p l a n t s were examined i n th e BC^ progeny of
(Cere s X Wel ls) X Wells c r o s s e s t o give a c c u r a t e measures
• of t h e f r e q u e n c i e s w i t h which u n i v a l e n t s a r e p a s s e d th r o u g h
female g am et es .
Sin ce only t h r e e c l a s s e s of F2 p r o g e n i e s from T h a t c h e r by durum c r o s s e s
d e v i a t e d w id el y from c a l c u l a t e d r a t i o s t h e second h y p o t h e s i s seems most
probable.
No D d i p l o s o m i c s were found' i n th e Fg p o p u l a t i o n . " S e v e r a l p l a n t s
w i t h numbers ap p r o a c h in g t h a t of d i p l o s o m i c s were o b s e r v e d .
The chromo­
some co m b in a ti o n s 15 j j + I j 9 1 5 j j + 2 j 9 1 5 j j + 3 j and 1 5 j j + 4 j o c c u r r e d
i n I , 4 , IO9 and 10 p l a n t s , r e s p e c t i v e l y .
Such c o m b in at io n s would be
e x p e c t e d t o produce some D d i p l o s o m i c s i n t h e .Fg.
One problem a s s o c i a t e d w i t h D d i p l o s o m i c s produced from normal hex a- ■
p l o i d X durum c r o s s e s i s t h e i d e n t i f i c a t i o n o f th e D chromosome c o n c e r n ­
ed.
Because of t h i s problem and bec a us e a h i g h e r f r e q u e n c y of D
d i p l o s o m i c s co ul d be e x p e c t e d i n c r o s s e s u s i n g Chinese S p r i n g D t e t r a s o m i c s , a second e x p e r i m e n t was con ducted i n c o n s i d e r a b l y more d e t a i l .
55 -
Experiment I I
Chromosome S e g r e g a t i o n and P r o d u c t i o n of D Diplo so mi cs From
T e t r a s o m i c X Durum C r o s s e s „
Of t h e many c y t o l o g i c a l s t u d i e s w i t h a n e u p l o i d s in w h e a t , only two
have d e a l t w i t h D d i p l o s o m i c s .
j
As mentioned e a r l i e r , Matsumura (1952b)
it
found a D d i p l o s o m i c i n t h e progeny of a p l a n t w it h t h e D hapl oso mi c
ji
chromosome c o m b in a ti o n 14 j j + I j ,
j
, ii
jj
The f e r t i l i t y of t h i s p l a n t was 68 p e r -
c e n t and of 113 progeny i n v e s t i g a t e d c y t o l b g i c a l l y only one r e v e r t e d t o
14 j i + l j .
genome.
some.
Matsumura c r o s s e d t h i s l i n e
As a r e s u l t , he i d e n t i f i e d th e
t o a s e t of n u l l i s o m i c s f o r t h e D
j
d i p l o s o m i c as h a v i n g a b chrome-
;!
The n u l l i s o m i c b , or b d w ar f , i n Matsumura1s c l a s s i f i c a t i o n , was
i:
th e same as S e a r ' s n u l l i s o m i c 6D (Matsumura 1952a) and t h e r e f o r e t h i s l i n e
^
was a 6D d i p l o s o m i c .
J
A 6D d i p l o s o m i c p l a n t was found in t h e p r e s e n t
s t u d y , b u t i t proved t o be c o m p l e t e l y s t e r i l e .
Dr. J . K. J o n e s - / has a l s o i s o l a t e d D d i p l o s o m i c s .
Dr. Jo nes and
i!
c o - w or ke r s found f o u r d i p l o s o m i c s i n t h e pr ogeny of a Tr i t i c u m ae sti v u m
by T r i t i c u m durum c r o s s .
One of t h e s e p l a n t s was s t e r i l e , b u t th e o t h e r
t h r e e produ ced 134 o f f s p r i n g o f which o n ly 11 were d i p l o s o m i c .
t h e pr ogeny had r e v e r t e d t o 1 4 j j or 1 4 j j + I j .
.
Most of
Because of t h e i n s t a b i l i t y
(
of th e D d i p l o s o m i c s , caus ed by f a i l u r e of t h e D genome chromosomes t o
p a i r i n 75 p e r c e n t of t h e m e i o t i c p o l l e n mother c e l l s , t h e s t u d y was
discontinued.
l / " P e r s o n a l communication from J . K. J o n e s , Department of A g r i c u l t u r a l
Bo ta ny , U n i v e r s i t y of Re ad in g, Re ad in g, Engl and, 1967.
)
' ||
j
56 -
The work r e p o r t e d i n t h e p r e s e n t s t u d y and t h a t o f Matsumura proves
t h a t s t a b l e l i n e s o f D d i p l o s o m i c s can be o b t a i n e d f o r a t l e a s t some
chromosomes.
The cau se o f t h e low f e r t i l i t y i n some l i n e s i s unknown.
S t e r i l i t y i n a n e u p l o i d s , such as t r i s o m i c s and t e t r a s o m i c s , has been
a t t r i b u t e d t o chromosome i m b a l a n c e .
This names th e phenomena, b u t i t does
not ex p lain the cause.
■ P l a n t s w i t h 15%% have o c c u r r e d in t h e progeny o f p l a n t s w i t h I b j i +
( l t o 4 ) j and 14 j j + I j .
In t h e p r e s e n t s t u d y o f T h a t c h e r X durum c r o s s e s ,
p l a n t s w i t h 1 5 j j +„ ( l t o 4 ) j o c c u r r e d w i t h a f r e q u e n c y o f 11% and p l a n t s
w i t h 14 j j + I j o c c u r r e d w i t h a f r e q u e n c y o f 9.12%.
Jon es ( p e r s o n a l
communication) o b t a i n e d 15 j j from 14 j j + I j p l a n t s w i t h a f r e q u e n c y o f
1.65%.
In e x p e r i m e n t I I o f t h e p r e s e n t s t u d y , 15 j j p l a n t s were o b t a i n e d
from 15 j j •+ ( l t o 4 ) j p l a n t s w i t h a f r e q u e n c y o f 7.95%.
The combined f r e ­
q u e n c i e s w i t h which 1 5 j j p l a n t s s h o u ld be o b t a i n e d . from 1 5 j j + (I to 4 ) j
and 1 4 j j + I j p l a n t s b as ed on t h e above d a t a i s 0.87% and 0.15%, r e s p e c ­
tively.
C o n s e q u e n t l y , s e l e c t i o n f o r 1 5 j j in t h e pr og eny o f 15 j j +
( l t o 4 ) j p l a n t s was p r o b a b l y more e f f i c i e n t .
The t e t r a s o m i c h e x a p l o i d X durum c r o s s e s produced F2 p l a n t s w i t h
1 5 j j + ( I t o 4 ) j w i t h a f r e q u e n c y o f 5.23%.
which 1 5 j j p l a n t s were o b t a i n e d was 0.42%.
The combined f r e q u e n c y with
S e l e c t i o n f o r 1 5 j j from
T h a t c h e r X durum c r o s s e s s h o u ld have been more e f f i c i e n t t h a n s e l e c t i o n
from t e t r a s o m i c h e x a p l o i d X durum c r o s s e s .
However, t h e t e t r a s o m i c
h e x a p l o i d X durum . c r o s s e s produced 15j j p l a n t s in which t h e e x t r a chromo­
some p a i r was p r o b a b l y d e r i v e d from t h e t e t r a s o m i c i n t h e o r i g i n a l c r o s s .
From t h i s s t a n d p o i n t t h e use o f t e t r a s o m i c h e x a p l o i d X durum c r o s s e s may
57 -
have been more e f f i c i e n t *
The p r im ar y o b j e c t i v e i n t h e i s o l a t i o n of D d i p l o s o m i c s was t o
p r o v i d e m a t e r i a l which c o u l d be used in s t u d y i n g th e g e n e t i c s of th e D
genome.
I f t h e . h e x a p l o i d p a r e n t were homozygous f o r a l l f a c t o r s c a r r i e d
on D genome chromosomes, t h e D d ip l o s o m ic s h o u ld a l s o be homozygous.
However, t h e r e was no r e a s o n t o e x p e c t t h a t t h e genes c a r r i e d by chromo­
somes i n t h e A and B genome were homozygous.
P r o b ab ly t h e D d i p l o s o m i c s
o b t a i n e d some chromosomes i n t h e s e genomes from t h e h e x a p l o i d p a r e n t and
some from t h e t e t r a p l o i d p a r e n t .
Some c h a r a c t e r s in th e D genome ar e
p r o b a b l y a l s o i n f l u e n c e d by genes i n t h e A and B genome.
I n o r d e r to
e l i m i n a t e t h e i n f l u e n c e of t h e s e g e n e s , i t would be d e s i r a b l e t o have a l l
genes i n t h e A and B genome d e r i v e d from one or t h e o t h e r of t h e p a r e n t s .
Once a D d i p l o s o m i c was o b t a i n e d , i t s h o u ld be p o s s i b l e t o b a c k c r o s s to
t h e p a r e n t v a r i e t y and a g a i n i s o l a t e t h e D d i p l o s o m i c .
R epe at ed back
c r o s s i n g f o ll o w e d by s e l e c t i o n s h o u ld e v e n t u a l l y r e s u l t i n progeny w i t h
a l l genes in t h e A and B genome homologous w i t h th o s e i n t h e r e c u r r e n t
parent.
The f r e q u e n c y w i t h which D d i p l o s o m i c s a r e o b t a i n e d from B d ip l o so m ic
X h e x a p l o i d c r o s s e s c o u l d be i n c r e a s e d by u s i n g n u l l i s o m i c or doubly
n u l l i s o m i c h e x a p l o i d l i n e s as t h e r e c u r r e n t p a r e n t .
For example, suppose
t h a t a ID d i p l o s o m i c were c r o s s e d t o a h e x a p l o i d p a r e n t n u l l i s o m i c f o r
chromosomes 2D and SB.
The F]_ progeny s h o u l d have 15 j j + 4 j and some
p l a n t s i n t h e Fg progeny s h o u l d have 15 j j „
Repeated b a c k c r o s s i n g fo ll o we d
by s e l e c t i o n i n th e Fg s h o u l d r e s u l t i n a D d ip l o s o m ic w i t h a l l i t s genes
d e r i v e d from t h e h e x a p l o i d p a t e n t .
-58 The D d i p l o s o m i c co ul d a l s o be b a c k c r o s s e d t o th e t e t r a p l o i d p a r e n t .
This would r e s u l t i n an
w i t h 14 j j + l j .
t h e chromosome c o m b in a ti o n I S j j ,
A few Fg p l a n t s s ho u ld have
Repeated b a c k c r o s s e s t o th e t e t r a p l o i d
p a r e n t fo ll o w ed by s e l e c t i o n f o r 1 5 u s h o u l d e v e n t u a l l y produce a
D d i p l o s o m i c w i t h a l l A and B genome chromosomes homozygous f o r genes from
th e t e t r a p l o i d p a r e n t and a l s o homozygous f o r one p a i r o f chromosomes from
th e h e x a p l o i d p a r e n t .
The i n f o r m a t i o n t o be g a i n e d from f u r t h e r s t u d y would d e t e r m in e
w h e th e r t h e work j u s t o u t l i n e d i s w a r r a n t e d .
SUMMARY
C r o s s e s between d i f f e r e n t s p e c i e s o f wheat have been t h e s u b j e c t o f
numerous s t u d i e s s i n c e t h e work o f Sakamura (1918)=
In r e c e n t y ea rs
a n e u p l o i d s have been used e x t e n s i v e l y f o r g e n e t i c s t u d i e s i n whe at.
C r o s s e s between wheat s p e c i e s w i t h d i f f e r e n t chromosome numbers can r e s u l t
i n t h e p r o d u c t i o n o f a n e u p l o i d s bec au se o f t h e s e g r e g a t i o n o f u n p a i r e d
chromosomes i n Fg and l a t e r g e n e r a t i o n s .
The p r e s e n t s t u d i e s were con cerned w i t h :
( 1 ) . The- d e t e r m i n a t i o n o f s e g r e g a t i o n r a t i o s in. t h e Fg of
t e t r a p l o i d by h e x a p l o i d c r o s s e s .
(2)
The d e t e r m i n a t i o n o f s e g r e g a t i o n r a t i o s -in Fg and l a t e r
g e n e r a t i o n s o f c r o s s e s between th e seven p o s s i b l e D
. t e t r a s o m i c h e x a p l o i d s o f Chinese S p r in g and t e t r a p l o i d
d drums.
(3)
The i s o l a t i o n o f D d i p l o s o m i c s from t h e l a t t e r c r o s s .
As a r e s u l t o f t h e s e s t u d i e s , th e f o l l o w i n g c o n c l u s i o n s a p p e a r to be
warranted:
E x pe r im en t I .
(l)
T h a t c h e r X durum c r o s s e s .
As i n p r e v i o u s s t u d i e s o f h e x a p l o i d X t e t r a p l o i d c r o s s e s ,
t h e f r e q u e n c y o f various- chromosome co m b in at i o n s o bs erv ed i n
Fg p l a n t s were n o t i n ag ree me nt w ith t h o s e e x p e c t e d on th e
b a s i s o f random s e g r e g a t i o n o f u n i v a l e n t chromosomes.
- 60
( 2 ) - The f r e q u e n c i e s w i t h which v a r i o u s chromosome co m bin ati on s
■ were e x p e c t e d in Fg p l a n t s was c a l c u l a t e d from th e f r e ­
q u e n c i e s w i t h which female gametes pa s s ed u n i v a l e n t s „
When
o b s e r v e d f r e q u e n c i e s o f v a r i o u s chromosome co m bin ati on s
were compared w i t h th e c a l c u l a t e d t h e c h i s q u a r e p r o b a b i l i t y
v a l u e was Q.25.
(3)
P l a n t s w i t h i s o s o m i c s , t e l o s o m i c s , and m u l t i v a l e n t s were
o b s e r v e d w i t h t h e f r e q u e n c i e s , 1.4%, 2.8%, and 5,1%,
respectively,
(4)
The f r e q u e n c i e s w i t h which p l a n t s w i t h t h e chromosome
c o m b i n a t i o n s 1 4 n + I j and 15%% + ( l t o 4)% o c c u r r e d ,
i n d i c a t e d t h a t D d i p l o s o m i c s could be o b t a i n e d . from t h e s e
crosses„
(5)
The r e s u l t s from e x p e r i m e n t I were in f u l l agreement w it h
previous s t u d i e s „
Ex p er i m en t I I ,
(1)
C hin es e S p r in g t e t r a s o m i c h e x a p l o i d X durum c r o s s e s .
N e a r ly 80% o f t h e Fg p l a n t s from t h e s e c r o s s e s c o n t a i n e d a t
l e a s t one o f each o f t h e p o s s i b l e 21 chromosomes„
(2)
The Fg p l a n t s w i t h 15%% + ( l t o 4)% produced a p p r e c i a b l y
more 15%% p l a n t s t h a n d i d t h o s e w it h 15%% + 5% o r 15%% + 6%.
(3)
D d i p l o s o m i c p l a n t s can be o b t a i n e d i n t h e F^ g e n e r a t i o n ,
b u t many a r e male s t e r i l e and f a i l t o prod uce s e e d s .
(4)
The f e r t i l e D d ip l o s o m i c s produced F4 p l a n t s a l l o f which
were a l s o D d i p l o s o m i c s .
- 61
(5)
The f o l l o w i n g P d i p l o s o m i c s were o b t a i n e d :
5D and 6D.
ID, 3D, 4D,
The f e r t i l e p l a n t s , presu mab ly d i p l o s o m i c f o r
chromosome 4D, and one f e r t i l e p l a n t p r es u m ab ly d ip l o s o m ic
f o r chromosome 5D were o b t a i n e d .
The r e m a in in g D
d i p l o s o m i c s were s t e r i l e .
(6)
A p r o c e d u r e f o r o b t a i n i n g D d i p l o s o m i c s w i t h a l l A and B
genome chromosomes homozygous was p r e s e n t e d .
■U - J L J ___ L
A P P E N D I X
)
-
T a b l e I..
63
F r e q u e n c i e s w i t h w h ic h g a m e t es w i t h v a r i o u s numbers o f chromo­
somes a r e e x p e c t e d t o form z y g o t e s , b a s e d on t h e f r e q u e n c y w i t h
w hi ch f e m a le g a m e t e s p a s s e d u n i v a l e n t s i n a c r o s s ,
(C e re s X W e l l s ) X W e l l s „
Female_____.
Chromo- F r e - ■
s ome No. auencv
___________ Chromosome No. in Male Gametes
14
17
15
■ 16
18
19
1 2 .7
11.3
15.5
17.0
7.0
2 2 .5
20
4 .2
21
9 .8
14
2 2 .5
.0506
.0349
.0286
.0 2 5 4
.0382
.0158
.0094
.0221
15
15.5
.0349
.0240
.0197
.0 1 7 5
.0263
.0109
. 0065
.0152
16
1 2. 7
.0286
.0197
.0161
.0144
.0216
.0089
.0 0 5 3
' .0124
17
11.3
.0254
.0175
.0 1 4 3
.0128
.0192
.0079
.0047
.0111
• 18
17.0
.0383
.0263
.0216
.0 1 9 2
.0289
.0119
.0071
.0167
19
7.0
.0 3 2 4
.0109
.0089
.0079
.0119
.0049
.0029
.0069
20
4.2
.0095
.0065
.0053
.0047
.0071
.0029
.0018
.0041-
9 .8
.0 2 2 0
.0151
.0124 ' .0111
.0167
.0 0 6 9
.0041
.0096
21
.
64
Ta bl e I I ,
P o s s i b l e chromosome c o m b i n a t i o n s , t h e gametes from which t h e y
co ul d be formed, p r o b a b i l i t y o f th e zygote bei ng o b t a i n e d and
f r e q u e n c y w i t h which u n i v a l e n t s i n d i f f e r e n t gametes ar e a l i k e
i n F2 p l a n t s o f T h a t c h e r X durum c r o s s e s . Based on Appendix
Ta b le I and d i f f e r e n c e s in t h e f r e q u e n c y w i t h which d i f f e r e n t
chromosomes were i n c l u d e d in g am e te s .
Column Number
2
I
1X 2
Total
Zvoote P a i r i n q Combined Frequem
Chromosome
Com bin ation
Possible
Gametes
14n
14 + 14
. 0506
1 .0 0 0 0
. 0506
14I I + 1I
14 + 15
15 + 14
.0349
.0349
1.0000
1.0 0 0 0
.0349
.0349 - .0698
14I I + 2 I
14
16
15 + 15
16 + 14
.0286
.0 2 4 0
.0286
1.0 0 0 0
0.8 5 7 1
1.0000
.0286
.0206
.0286
.0778
14
15
16
17
+
+
+
+
17
16
15
14
.0 2 5 4
.0 1 9 7
.0 1 9 7
.0 2 5 4
1 .0 0 0 0
0 .7 1 4 3
0 .7 1 4 3
I .0000
.0 2 5 4
.0141
.0141
.0 2 5 4
.0790
14
15
16
17
18
+
+
+
+
+
18
17
16
15
14
.0383
.0175
.0161
.0 1 7 5
.0 3 8 2
1.0000
0 .5 7 1 4
0 .4 7 6 2
0.5714
I .0000
.0383
.0 1 0 0
.0077
.0100
.0383
.1043
14
15
16
17
18
19
+
+
+
+
+
+
19
18
17
16
15
14
.0324
.0263
.0143
.0 1 4 4
.0263
.0158
1.0 0 0 0
0.4 2 8 6
0.2 8 5 7
0.2 8 5 7
0.4 2 8 6
I .0000
.0 3 2 4
.0113
.0041
.0041
■.0112
.0 3 2 4
.0955
14
15
16
17
18
19
20
+
+
+
+
+
+
+
20
.19
18
17
16
15
14
.0095
.0 1 0 9
.0216
.0128
.0 2 1 6
.0 1 0 9
.0 0 9 4
1.0000
0 .2 8 5 7
0.1 4 2 9
0 .1 1 4 3
0 .1 4 2 9
0 .2 8 5 7
1.0 0 0 0
.0095
.0031
.0031
.0015
.0031
.0031
.0095
.0329
I 4 H + Si
I4 II + 4I
I 4 H + S1
14I I + 6 I
.
. 0506
- 65 -
Column Number
Chromosome
Possible
I_________ 2
1X 2
T o ta l
Com bin ation _________________Gametes_______Zygote P a i r i n g Combined Frequency
1 4 n + 7l
+
+
+
+
+
+
+
+
21
20
19
18
17
16
15
14
.0 2 2 0
. 0065
.0089
.0 1 9 2
.0 1 9 2
.0 0 8 9
. 0065
.0221
1.0000
0 .1 4 2 9
0.0 4 7 8
0 .0 2 8 6
0 .0 2 8 6
0.0 4 7 8
0 .1 4 2 9
I -. 0000
.0 2 2 0
.0009
.0 0 0 4
.0005
.0005
.0004
.0009
.0221
.0477
15n •
15 + 15
. 0240
0 .1 4 2 9
.0 0 3 4
.0034
15I I + I i
15 + 16
16 + 15
.0197
.0197
0 .2 8 5 7
0.2 8 5 7
.0056
. 0056
.0112
15II + 2 i
15 + 17
16 + 16
17 + 15
.0 1 7 5
.0161
.0175
0 .4 2 8 6
0 .4 7 6 2
0 .4 2 8 6
.0075
.0077
.0075
.0227
15
16
17
18
+
+
+
+
18
17
16
15
.0263
.0 1 4 3
.0 1 4 4
.0 2 6 3
0 .5 7 1 4
0.571 4
0 .5 7 1 4
0 .5 7 1 4
.0150
.0082
.0082
.0150
.0464
15
16
17
18
19
+
+
+
+
+
19
18
17
16
15
.0109
.0216
.0128
.0216
.0109
0.714 3
0.571 4
0 .5 1 4 2
0 .5 7 1 4
0 .7 1 4 3
.0078
.0123
o0066
.0123
.0078
.0468
15
16
17
18
19
20
+
+
+
+
+
+
20
19
18
17
16
15
.0065'
.0089
.0192
.0 1 9 2
.0 0 8 9
. 0065
0.8571
0.4761
0 .3 4 2 9
0 .3 4 2 9
0.4761
0.8571
. 0056
.0042
. 0066
.0066
.0042
.0056
.0328
15
16
17
18
19
20
21
+
+
+
+
+
+
+
21
20
19
18
17
16
15
.0152
.0 0 5 3
.0079
.0 2 8 9
.0079
.0 0 5 3
.0152
1.0 0 0 0
0.2 8 5 7
0 .1 4 2 9
0.1143
0 .1 4 2 9
0.2 8 5 7
1.0000
.0152
.0015
.0011
.0 0 3 3
.0011
.0015
.0152
.0389
15I I + 3 I
15H + 4 I
1 5 n + 5I
l—l
t—I
If)
I—I
-+ 6l
14
15
16
17
18
19
20
21
-
66
Column Number
Chromosome
Possible
I_________ 2_______1 X 2
Total
Com bination_________________ Gametes_______Zygote P a i r i n g Combined Frequency
16 i I
16 + 16
.0161
0.0 4 7 6
.0008
.0008
16n + ii
16 + 17
17 + 16
.0143
.0 1 4 3
0 .1 4 2 9
0 .1 4 2 9
.0 0 2 0
.0 0 2 0
.0040
16 + 18
17 + 17
18 + 16
.0216
.0128
.0216
0.2 8 5 7
0.3 4 2 9
0 .2 8 5 7
.0062
.0044
.0062
.0168
16
17
18
19
+
+
+
+
19
18
17
16
.0089
.0192
.0 1 9 2
.0 0 8 9
0.4761
0.5 1 4 2
0 .5 1 4 2
0.4 7 6 1
.0042
.0099
.0099
.0042
.0282
16
17
18
19
20
+
+
+
+
+
20
19
18
17
16
.0 0 5 3
.0079
.0 2 8 9
.0 0 7 9
.0 0 5 3
0 .7 1 4 3
0 .5 7 1 4
0 .5 1 4 3
0 .5 7 1 4
0.7143
.0038
.0045
.0149
.0045
.0038
.0315
16
17
18
19
20
21
+
+
+
+
+
+
21
20
19
18
17
16
.0124
.0047
.0119
.0119
.0047
.0124
1.0000
0 .4 2 8 5
0.2 8 5 7
. 0.2857
0 .4 2 8 5
1 ,0 0 0 0
.0124
.0 0 2 0
.0 0 3 4
.0 0 3 4
.0 0 2 0
.0124
.0356
17 + 17
.0128
0 .2 8 6
.0 0 0 3
.0003
17I I + 1I
17 + 18
18 + 17
.0192
.0 1 9 2
0 .1 1 4 3
0.114 3
.0022
.0022
.0044
I?!! + 2I
17 + 19
18 + 18
19 + 17
.0079
.0289
.0 0 7 9
0.2857
0.3 4 2 9
0.2 8 5 7
.0022
.0099
.0 0 2 2
.0143
17
18
18
20
.0047
.0119'
.0119
.0 0 4 7
0.5 7 1 4
0.5714
0 .5 7 1 4
0 .5 7 1 4
.0027
.. ,0 0 6 8
.0068
.0027
.0190
16I I + 2 I
16H + 3 I
I b 11 + 4l
16 I I + 5 I
17II
1 7 n + 3I
.
+
+
+
+
20
19
18
17
67
Chromosome
Com bination
Possible
Gametes
,
Column Number
2
1X 2
Total
I
Zyqote P a i r i n q Combined F r e quencv
17 + 21
18 + 2 0
19 + 19
■ 20+18
21 + 17
.0111
.0071
.0049
.0071
.0111
1.0000
0 .5 7 1 4
0 .4 7 6 2
0.571 4
I .0000
.0111
.0041
.0023
.0042
.0111
.0328
18II
18 + 18
.0289
0 .0 2 8 5
.0008
.0008
18I I + 1 I
18 + 19
19 + 18
.0 1 1 9
.0119
0 .1 4 2 9
0 .1 4 2 9
.0017
.0017
.0034
1 8 n + 2x
18 + 20
19 + 19
20 + 18
.0071.0049
.0071
0 .4 2 8 6
0 .4 7 6 2
0 .4 2 8 6
.0 0 3 0
.0023
.0 0 3 0
.0083
18
19
20
21
21
20
19
18
.0167
.0029
.0029
.0167
1 .0 0 0 0
0.7143
0.7143
1.0000
.0167
.0021
.0021
.0167
.0376
19n
19 + 19
.0049
0 .0 4 7 6
.0002
.0002
1^ i I + 1I
19 + 20
20 + 19
.0029
.0029
0.2 8 5 7
0 .2 8 5 7
.0008
.0008
.0016
19I I + 2 I
19 + 21
20 + 20
21+19
.0069
.0018
.0 0 6 9
1.0000
0.8571
I . 0000
.0069
.0015
.0069
i 0153
20n
2 0 .+ 20
.0018
0.1429
.0002 '
.0002
2 0 n + 11
20 + 21.
21 + 20
.0041
.0041
I . 0000
1 . 0 0 0 0
.0041
.0041
.0082
21 + 21
.0 0 9 6
1.0000
.0 0 9 6
.0096
17I I + 4 I
l—■
M
M
18I I + 3 I
+
+
+
+
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29-chromosome D
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________/
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The e f f e c t o f chromosome ID on
Crop S c i e n c e , 4: 32 0- 323 .
D 378
J74 8
c o p .2
J o p p a , L.R.
Chromosome s e g r e g a ­
t i o n in a Triticum
a e s t i v u m L. em. T h e l l . by T.
riirrnm
frrt.g g anH t.h e
NAW K JP H g A O D R S S S
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T *7 ,y
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