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Results and Discussion
The differential response between T. turgidum (AABB)
and T. timopheevi (AAGG) was shown by the proportion
of abortive seed production in the crosses to
(squarrosa)AABB+1D lines as seen in Fig.
1. Fig. 1-a shows the crossed
seeds obtained from one spike of (squarrosa) T.
turgidum+1D line fertilized by the pollen of
T. turgidum, in which five normal seeds (in left) had
the genetic constitution of
(squarrosa)AABB+1D, and were capable to
germinate. The other thirty-one abortive seeds (in right)
were zygotic lethal, and were presumed to have the genetic
constitution of (squarrosa)AABB. In these abortive
seeds, the seed coat that originated from tissue of female
parent developed, while the embryo and the endosperm did not
differenciate.
Fig. 1-b shows the crossed seeds
which were obtained from one spike of the same plants as
Fig. 1-a fertilized with pollen of
T. timopheevi. Majority of female gamete of this
(squarrosa) AABB+1D plant must not have
1D chromosome, because the transmission rate of the
additional 1D chromosome through female gamete was
24.8% on average. In spite of this low transmission rate of
1D chromosome through female gametes, all zygotes
developed to normal seeds, and were able to germinate. This
result and the observation of OHTSUKA (1980) suggest that
genetic factor(s) of G genome for the genome compatibility
with the cytoplasm of Ae. squarrosa is equivalent to
that of 1D chromosome.
The differential response of AB and AG genomes to Ae.
squarrosa cytoplasm was also observed when
(squarrosa)T. dicoccoides+1D-1A
and (squarrosa)T. durum+1D were used as
female parents in the crosses. The ratio of normal to
abortive seeds on female plants of (squarrosa) T.
durum+1D was similar to that on
(squarrosa) T. turgdium+1D. However,
this ratio on (squarrosa) T.
dicoccoides+1D-1A line was different from
that on either of 1D monosomic-addition lines as
shown in Table 1. This might be
due to the difference in their transmission rates of
1D chromosome through female gametes.
The results from the crosses of eleven species or strains of
tetraploid wheat as pollen parents to the monosomic-addition
lines and the monosomic-substitution line having Ae.
squarrosa cytoplasm were showed in Table
1. Five species of Emmer wheat and two varieties of
Palaestaine-T. dicoccoides were classified as AB
type, because many abortive seeds were produced. Percentage
of abortive seeds in the crossed seeds were 61.7%-86.0% and
38.1%-61.9% When (squarrosa)AABB+1D and
(squarrosa)AABB+1D-1A line were used as
female parent, respectively. These figures reflected the
frequency of the female gametes without 1D
chromosome.
Three strains of Trans-Caucasian-Timopheevi wheat, and two
species of Trans-Caucasian-endemic species, T.
palaeocolchicum MEN. (=T. georgicum DEK.) and
T. persicum VAV. (=T. carthlicum NEVSKI)
showed the AG type response, because abortive seeds were not
or almost not produced in the crosses. However, T.
palaeoclchicum and T. persicum have been
classified as Emmer group with AABB genome.
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