Trigenomic combinations for the analysis of meiotic control in the cultivated Brassica species

Abstract

Haploid hybrids of either Brassica campestris (AA) or B. oleracea (CC) with B. nigra (BB) show a relatively low amount of chromosome pairing as compared with the level observed in the hybrid B. campestris × B. oleracea. This finding led to assume that B. nigra may carry a genic system suppressing homoeologous pairing in Brassica. To test this hypothesis, trigenomic hybrids (genome constitution ABC, 2n = 27) were synthesized, in which the effect of the B genome on the homoeologous pairing of the A and C genomes could be measured. The results indicate the inability of B. nigra to affect the level of pairing between homoeologous chromosomes of the A and C genomes. No genetic factor for a suppression of pairing was found in the B genome and there were no cytoplasmic effects on the regulation of pairing. However, cytological evidence pointed to chances of a successful transfer of economically valuable genes from B. nigra into the A and C genomes through the normal events of meiotic recombination. Key words: Brassica, triploid (trigenomic), homoeologous pairing, gene transfer.