Cytological And Genetic Analyses Of Hybrid Progenies Between Brassica Rapa And Orychophragmus Violaceus

Previous studies have indicated that one of the wide hybrids between Brassica rapa ssp.chinesis L.(2n=20, AA) and Orychophragmus violaceus (L.) O.E.Schulz (2n=24,00) is a mixopolyploid (2n=23-42) resulted from the parental genome separation.39different lines which show very different morphology are gained from the hybrid after consecutive self-crossing. Here, we analyzed the genome composition and the meiotic chromosome behavior of different lines by the methods of cytology observation, Fluorescence in situ hybridization (FISH) and Sequence-Related Amplified Polymorphism (SRAP). The results together with the phenotypic variation data provided potential cellular and molecular mechanism for the process of different lines formation and indicated potential applications of these lines in Brassica breeding. Main results were described as follows:1. The morphological characters varied much among different lines. The differences were found mainly in plant shape, plant height, leaf colour, flowering time, pollen stainability, fatty acid compositions, oil and glucobrassicin content.2. Different lines had different chromosome composition including Brassica A and C genome chromosomes but without chromosome from O. violaceus. The karyotype of39lines could be divided into8groups:20A+18C(13),22A+16C(12),23A+16C(2),23A+15C(2),21A+16C(2),20A+17C(1),20A+19C(1) and20A+16C(1).3. Although majority of chromosomes could be paired into bivalents, quadrivalent was also found in some of pollen mother cells from every line except for line14. However, the number and the rate of quadrivalents varied among different lines.4. SRAP analysis showed that intergeneric DNA introgression from O. violaceus was common in all lines, which might contributed to the phenotypic variation at least in some of the lines.