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Cabbage (Brassica oleraces var.capitata L.) is native to the Mediterranean coast in the 16th century into China, after more than 300 years of development, has become one of the country's major vegetable crops. Downy mildew is one of the important diseases in cabbage production, in some areas there is a clear upward trend, breeding disease-resistant varieties is the most effective way to address this disease. In recent years, with the deepening of research in molecular biology, molecular marker-assisted breeding for disease resistance of cabbage to show great potential. After screening has been excellent resistance to downy mildew inbred lines, but with the process of resistance Genes turn sterile field resistance Inoculation screening procedures resistant plants, and is affected by the environment, time-consuming, so looking closely linked to the resistance gene stable, simple molecular markers can be identified in any other period of growth and development, Jane Engineering Festival this will greatly improve the efficiency of cabbage breeding for disease resistance. The experiment after multiple generations from the cross-breeding of the 'R103' resistant inbreds and 'S101' susceptible inbred lines based on their Inheritance of Resistance. 2 separation groups on the basis of, 'R103' and 'S101' hybrid build F in downy mildew disease peak period of three disease surveys, field natural identification of resistance induced by BSA method selected extreme resistance to disease and extreme susceptible F 2 per plant to build two different anti-flu pool using AFLP and screening and anti-gene molecular markers linked to downy mildew, and then the conversion of AFLP markers SCAR markers. The main findings are as follows: (1) According to the field of natural disease 'S101' disease symptoms, and microscopic examination of pathogen and tieback identification, clear the pathogen of the disease are the the cruciferous cream mold (Peronospora parasitica). Induced field natural identification, the investigation found that parent for a small amount of several strains of performance susceptible backcross parent groups BC 1 , the entire group were highly resistant to disease resistance, using a five-point method basically no anti- sexual separation: a sense of sick parents backcross parent BC 1 groups in the proportion of resistant strains, and a sense of diseased plants is 0.91:1, by chi-square for testing in line with the proportion of 1:1 segregation; F 2 segregating population, the proportion of the resistant plants and susceptible plants 2.93:1 detection results by chi-square analysis demonstrate compliance with the separation ratio of 3:1, thus indicating that these groups by a single gene dominant control of downy mildew resistance. (2) the use of AFLP and BSA F 2 groups take extreme resistance to disease and extreme susceptibility monoclonal build two different anti-flu pool, eight of the EcoR 1 primers, 8 Mse1 cited material composed of 64 pairs of primer combinations, a confrontation flu pool downy mildew disease resistance gene chain of AFLP markers conducted a screening, screening to Dui primer combinations differential fragments, but by the parent and the other one confrontation the susceptible pools identification results EcoR 1-AAG/Mse 1-CTC and EcoR 1-AAC/Mse 1-the CAC two pairs of primers combination selected in the disease pool and resistant parent and disease-related differences in fragment BOR < sub> AAG / CTC and BoR AAC / CAC . (3) The AFLP markers BOR AAG / CTC and BoR AAC / CAC fragment recovered clones, and transformed into E. coli E.coli DH5α, and then extract the plasmid sequencing, designed according to the sequence of measurement results of SCAR primers, and detection of genomic DNA of 160 individuals, parents, and two pairs of pools and F 2 groups, repeated three times, the results are stable. BoR AAC / CAC fragment
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