Genomic in situ hybridization as a means of analysing chromosome pairing in Triticum aestivumXThinopyrum ponticum hybrids

Chen, Q.; Conner, R.L.; Ahmad, F.

Journal of Genetics and Breeding 56(3): 237-244


Accession: 010712184

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Genomic in situ hybridization (GISH) using S genomic DNA from Pseudoroegneria libanotica as a probe was applied to examine the genomic composition and chromosome pairing of Thinopyrum ponticum and its intergeneric hybrids with Triticum aestivum. GISH analysis detected 42 J and 28 JS chromosomes in Th. ponticum. Most intergeneric hybrids of wheatXTh. ponticum carried 56 chromosomes which included 21 wheat plus 21 J and 14 JS genome chromosomes (ABDJJJJSJS genomes). High pairing frequencies among Th. ponticum J and JS genome chromosomes and a low pairing frequency among wheat ABD chromosomes indicated that the relationships among the five sets of the J and JS genomes of Th. ponticum are much closer than those of the ABD genomes of wheat. It was further observed that JS-JS ring bivalents and J-J-J trivalents occurred at a higher frequency than other chromosome-pairing configurations. This provides additional evidence that supports the JJJJSJS genomic composition of Th. ponticum. The occurrence of heterologous pairing between J-W and JS-W chromosomes, albeit at a low frequency, also provides an indication about the relationship existing between the J and JS genome chromosomes and the wheat chromosomes.