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Wheat Information
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Number 72: 103 (1991)
On the
origin of rye B chromosomes
K. Niwa and S. Sakamoto
Plant Germ-plasm Institute, Faculty of Agriculture, Kyoto
University, Mozume, Muko, Kyoto 617, Japan
Rye B chromosomes from different regions are very similar in their
morphology at somatic metaphase. The present study aimed to elucidate
the relationships between rye B chromosomes in three different
regions, Afghanistan, Turkey and Korea.
We carried out the following crosses, Afghan S. segetale (2B)
x Turkish S. cereale (2B) and Afghan S. segetale
(2B) x Korean
S. cereale (2B). We selected their F1 hybrids with
four B chromosomes, which are considered to have the B chromosomes
transmitted from both the pollen parent and the pistillate one, and
observed the chromosome pairing of B chromosomes at diakinesis of
pollen mother cells in the F1 hybrids with four B
chromosomes.
In ten F1 hybrids with four B chromosomes obtained from
Afghan S. segetale (2B) x Turkish S. cereale (2B), the
frequency of the pollen mother cells showing
multivalents
(1III + 1I and
1IV)
of B chromosomes
varied from 12 to 38%. In 15 F1 hybrids with four B
chromosomes obtained from Afghan S. segetale (2B) x Korean
S. cereale (2B), 8 to 32% of the pollen mother cells observed
showed multivalents (1III + 1I and
1IV)
of B chromosomes.
Compared with the parental strains with four B chromosomes, the
degree of the multivalent formation of B chromosomes in the
F1 hybrids is similar or somewhat low. These results
indicate that the rye B chromosomes from Afghanistan, Turkey and
Korea are homologous one another.
Therefore, we concluded that the origin of rye B chromosomes from
these three different areas is most probably monophyletic. Further,
we are going on to clarify the relationships of rye B chromosomes
from Afghanistan to those from other countries, Iran and Japan.
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