Brassica Cytoplasmic Male Sterility Of Cell And Molecular Biology Of Basic Research

Chinese cabbage (Brassica campestrts) is one of the most important culture vegetable crops in China The cultivated Chinese cabbage (Brassica campestris L. chineses Makine) is a diploid species (2n= 20) with a nuclear DNA content of 507 Mbp/lC. Since 1980 a cytoplasmic male sterile line, transferred frompolma cytoplasmic Brassica, has been created and is intensively employed in Fl hybrid seed production in China.To undertake the molecular mechanism of the cytoplasmic male sterility, we explored to address the role of the nucleus factor and cytoplasm factor on the development of the cytoplasmic male sterility and their interaction. Firstly, the bulked DNA-RAPD analysis was performed with chromosome DNA of the sterile line and fertile line and genetic analyzed on a population resulted from crossing of the sterile line with the fertile line (maintain line). The population consisted of 152 individuals including 88 fertile phenotype plants and 64 sterile phenotype plants. 98 RAPD primers were tested in a bulked segregant analysis leading to identification of 14 primers that gave clear polymorphic RAPD markers between fertile and sterile plants. The linkage analysis with these 14 primers revealed 4 RAPD markers on 152 individual plants. Thus, a linkage map was constructed using the JoinMap 2.0. Four RAPD loci were located on one same chromosome with a genetic distance of 24,38 cM, and the s60-900bp was mapped in an interval of 4 cM. This RAPD marker was cloned and sequenced, and blasted Arabidopsis genbank. The results showed this RAPD marker was 37% homologized with the MSI transcriptional factor protein, which was related to the development of the pollen. The southern-analysis revealed that this sequence gave strong different hybridization signals on chromosome DNA of the fertile plants and the sterile line.Secondly, the same bulked DNA-RAPD analysis was performed with mitochondria! DNA of the sterile line and fertile line. 14 RAPD primers gave clear polymorphic RAPDs between the fertile plants and the sterile plants. The s33-1200bp RAPD marker was cloned and sequenced, and blasted Arabidopsis genbank. The results showed this RAPD marker was 96% homologized with the 4* subunit of NADH enzyme in Brassica rape mitochondrial genome. The result of southern hybridization showed that the hybridization signals appeared on chromosome DNA of the fertile plants but without on the sterile line. This result indicated the RAPD marker related cms come from mitochondrial genome also existed in chromosome genome. It was suggested that thecytoplasmic male sterility was affected by both nucleus factor and cytoplasm factor and the controlling factor may be come from the nucleus.