Effect of nullisomy for D-genome chromosomes and chromosome 5B on the cytological characteristics of pentaploid Triticum aestivum × T. dicoccoides hybrids

The effect of nullisomy for D-genome chromosomes and chromosome 5B on the meiotic behaviour of pollen mother cell chromosomes of pentaploid F1 hybrids of Triticum aestivum (cv. Bezostaya 1) × T. dicoccoides (Korn) was studied. The functional ability of female gametes with diverse chromosome constitution and the frequency of their inheritance in BC1 was assessed. Absence of individual T. aestivum D-genome chromosomes had a specific effect on meiotic chromosome pairing. The genetic systems involving chromosome 5B of the two species did not have the same effect on homologous and homoeologous chromosome pairing. Chromosome 5B of T. dicoccoides reduced bivalent pairing and increased multivalent associations. In BC1 the frequency of female gametes with n = 16–18 chromosomes was highest. Key words: nullisomy, chromosome pairing, Triticum, pentaploid hybrids.