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The endosperm development in all hybrids, except hybrid kernels
produced by 3D (3B) and 6D(6B), was very poor and all of the kernels
were shrivelled. However, hybrid kernels produced by 3D(3B)
germinated (5.9%), while no hybrid kernels produced by other
substitution lines germinated. These data indicate that the 3D
chromosome may contribute to the development of embryo. At the same
time, Miller et al. (1983) reported that 3D chromosome effected
embryo development in Chinese Spring x Hordeum bulbosum
crosses.
From the results of this study, it was demonstrated that not only
chromosome 5B, 5A and 5D, but also chromosome 3A and 3 B were
involved in the crossability of wheat with Secale cereale .
Also, 3D chromosome may be contributing to the development of
embryo.
Aegilops squarrosa x D-genome substitution lines
Crossability of D genome substitution lines of Langdon with
Aegilops squarrosa is presented in Table
2.
As can be seen in Table 2, a wide range in
crossability percentage was obtained by crosses of Aegilops
sguarrosa x LDN-D genome substitution lines. When the
crossability percentages are compared, it was shown that in 3D(3A),
6D(6A), 3D(3B) and 6D(6B) disomic substitution lines it was higher
than other disomic substitution lines. The crossability percentage of
these lines ranged from 15.0 % to 46.2 %, while in six substitution
lines viz. lD(lA), 2D(2A), lD(lB), 2D(2B), 4D(4B)and 7D(7B), it
ranged from 3.6 % to 9.4 %. The crossability of the control and
5D(5A), 7D(7A) and 5D(5B) lines were zero. This result suggested that
3A, 6A, 3B and 6B chromosomes had a gene/ genes that inhibit crosses
between Aegilops squarrosa and durum wheat. It has been
clearly shown that chromosome 5D is also responsible for the
crossability of wheat with Aegilops squarrosa. At the same
time, Koba and Shimada (1993) reported that, like 5A and 5B, 5D
chromosome carried genetic factor(s) controlling the crossability
with Aegilops squarrosa.
The endosperm development in all hybrid kernels, except hybrid
kernels produced by 6D(6A), 6D(6B) and 2D(2B), was very poor and all
kernels were shriveled. The hybrid kernels produced by 6D(6B)
germinated (6.7 %), while no hybrid kernels produced by other
substitution lines germinated. This results suggested that 6D
chromosome may be partly responsible for the embryo development of
Aegilops squarrosa x durum wheat crosses.
However, we could have had a permissive accession of Aegilops
squarrosa because most researchers have found it very difficult
to cross Aegilops squarrosa with wheat when Aegilops
squarrosa used as the female (Dr. Joppa, pers. com.). At the same
time, if we can find a permissive accessions of Aegilops
squarrosa, this accession(s) could be used to improve new durum
or bread wheat in future.
Also, main reasons for low and high crossability of Langdon D-genome
substitution lines with Aegilops squarrosa can be the technique used,
and climatic conditions during crossing. Similar results were
obtained in wheat x Aegilops crosses by Ozgen (1983).
Acknowledgements
We acknowledge Dr. L.R. Joppa, North Dakota State University, for
supplying the seed of Langdon D genome chromosome substitution lines.
Also, We thanks Dr. L.R. Joppa and Dr. S.M. Reader (John Innes
Centre, Cereals Research Department, UK) for their valuable critical
renew of the manuscript.
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