Brassica Rape And O. Violaceus Distant Hybridization Studies And Orychophrogmus Applied Research

Systematic study was made on wide hybridization between Brassica napus and Orychophragmus violaceus (L. )O. E. Schalz in this experiment. In the firstly synthe sized intergeneric hybrid between B. napus and O. violaceus, the phenomenon of genome separation during mitosis of the hybrid cell was observed. During mitosis genomes from the two parent species were arrarged separately in the hybrid cells and later separated, resulting in formation of two types of haploid cells with gamete chromosome numbers of the two species. The two types of haploid cells doubled their chromosomes naturally. So various cells existed with 38, 31, 24, 19 and 12 chromosomes in the hybrid, and the hybrid turned out to be the allo—mixoploids of the two species. The cells with 24 and 12 chromosomes were nuclear — cytoplasmic hybrid (NCH) cells with nuclei of O. violaceus and the cytoplasm of B. napus. PMCs with the same numbers of bivalents as those of the two species were found in the hybrid. Among the selfed progeny of the hybrid, there existed plants of B. napus and hybrids of the two species, showing the fertile gametes produced by the cells of the two species respectively. The hybrids among the selfed progeny also produced B. napus and the hybrids, indicating that the genome separation was very similar to Mendel's Segrgation Law.The phenomenon of cell elimination was investigated during the growth process of the hybrid plants and fast mutiplication of the hybrid buds by tissue culture. It referred to that the NCH cells with the chromosomes of O. violaceus were gradually e-liminated and produced fewer gametes than those of the cells of B. napus in the hybrid, r suiting in different transmission rates of genomes from the two species. Thedifferent growth competition abilities of cells with the chromosomes.of the two species in the hybrid were responsible for the different transmission rates of genomes.In the doubled hybrid between B. napus and O- violaceus, there were eight kinds of somatic cells: haploid? diploid and tetraploid cells of B. napus and NCH, hybrid and doubled hybrid cells. The doubled hybrid produced five kinds of PMCs with 38. 31, 24, 19 and 12 bivalents respectively. Twelve kinds of progeny would be formed by the doubled hybrid through self — crossing. It is possible to obtain stable am-phidiploids of B. napus and O. violaceus, for the genomes of the two species were not separated in the doubled hybrid cells.The mechanism of genome separation such as different chromosome behaviours, chromosome recognition and genetic control were put out. The possible applications of the hybrid on plant genetics and breeding were discussed.