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FISH analysis using total
genomic Ae. speltoides DNA
In all tetraploid wheats, the B or G genome chromatin was easily
distinguished from the A genome chromatin, because the Ae.
speltoides probe was preferentially hybridized to the B or G
genome chromosomes. No hybridization sites were observed in any
chromosomes of the diploid wheat. Three A genome chromosomes of T.
dicoccoides showed terminal translocation: one is on the long arm
and two are on the short arm. In T. dicoccum, two
chromosomes showed terminal translocation in the long arm. One
chromosome carried two hybridization sites at terminal position in
the short arm and in the middle of the long arm.
The FISH pattern of T. araraticum showed three kinds of
chromosome translocations. The satellite and the proximal 30% of the
short arm of chromosome 6A were labeled. Two other A genome
chromosomes had only a localized telomeric or interstitial ISH
sites.
Nonhomoeologous translocation between chromosomes 6A, 1G and 4G in
the timopheevi wheats
As for the present structures of chromosomes 6A, 1G, and 4G and
their origins, we can speculate a hypothesi s involving two
translocation events, as shown in Fig.
2. The most
possible course of events is a reciprocal interchromosomal
translocation of the ori ginal 1G short arm including the satellite
and the original 6A short ar1GS-6AS breakpoint, and part of the
original 4G short arm. The presence of a tiny segment of the G genome
chromatin in two other A genome chromosomes can be explained by
transposition, but its mechanism is unknown. Further molecular
evidence of these intergenomic translocations, as Liu et al (1992)
pointed out, will be achieved by the development of RFLP-based
genetic map.
Acknowledgments
This work was supported in part by a Grant-in-Aid for Scientific
Research (No. 04305009) from the Ministry of Education, Science and
Culture, Japan and a grant from Sapporo Bioscience Foundation,
Japan.
References
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