Genome analysis in Triticum zhukovskyi, a new hexaploid wheat
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The karyotype of T. zhukovskyi, a hexaploid wheat recently recorded from Western Georgia of the U.S.S.R., revealed that it has 3 pairs of satellited chromosomes. Two of these resemble closely the two pairs present in T. timopheevi. The other pair is similar in arm ratio to the pair found in T. monococcum var. hornemanni. Micro-satellites usually found in varieties of T. monococcum did not occur in T. zhukovskyi.
A maximum of 4 quadrivalents per cell was found at meiosis in T. zhukovskyi, the average being 1.35 per cell. Pollen and seed fertility were normal.
In crosses between T. zhukovskyi and T. spelta, T. macha and T. vavilovi, only the F1 plants of the cross with spelta survived. There was an average frequency of 15.1 univalents per cell in the zhukovskyispelta hybrid. Thus, the partial failure of chromosome pairing in this hybrid is similar to that usually found in hybrids between T. timopheevi and other tetraploid species.
From a discussion of the data, it is suggested that T. zhukovskyi might have arisen through chromosome doubling in the hybrid T. timopheevi × T. monococcum var. hornemanni. If this conclusion is supported by future experiments, T. zhukovskyi will be the first hexaploid wheat to have a genomic constitution other than ABD.
KeywordsDevelopmental Biology Genome Analysis Future Experiment Chromosome Pairing Average Frequency
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