The influence of rye cytoplasm on meiotic stability of tetraploid Secalotriticum.

Chromosome pairing in tetraploid Secalotriticum was analysed. In the studied plants wheat chromosomes in PMCs during metaphase I showed a higher degree of pairing, in comparison to the rye genome. This is reflected in a very low frequency of univalents and a higher frequency of ring bivalents. The occurrence of wheat univalents was dependent on wheat mixogenome. In plants with an unstabilized fourth homoeologous group, a heteromorphic bivalent 4A-4B was observed in 39.9% of PMCs, whereas in plants with an unstabilized seventh homoeologous group, chromosome 7A-7B pairing was found in all analysed cells. Rye univalents were present in all plants studied. The highest mean frequency of univalents and rod bivalents, both in wheat and in rye genomes, were recorded in plants whose first homoeologous group contained chromosome 1A. The mean number of terminal chiasmata per chromosome amounted to 1.78 in the wheat genome and 1.36 in the rye genome. It may be concluded that the plasmagenes in Secalotriticum did not increase the meiotic stability of the rye genome and also did not stabilize plant fertility.