| Sclerotinia disease of rapeseed, caused by fungal pathogen Sclerotinia sclerotiorum, is the most destructive disease worldwide and especially serious in southeast and Yangtz Rive Area of China. No completely resistant cultivars have been identified in rapeseed, as well as in the closely related species. Resistance to Sclerotinia sclerotiorum in rapeseed is quantitative trait and easily affected by environment condition. There is no accepted widely identification resistance method. These questions make breeders difficult to select really resistant plants. The objectives of our research were to 1) screen more precise identification resistance method, 2) systematically study inheritance of resistance, 3)map the quantitative resistance loci with molecular markers, which have important meaning for transforming resistant gene from resistant materials to major cultivars.We compare different identification resistance methods at seedling and maturing stage with 12 resistant and susceptible materials, analyze inheritance of resistance in cross of DH821 DHBao604 with multi-generations (P1, P2, F1, BC1, BC2, F2) and DH (doubled haploid) population, identify resistance of DH population at different development stage with different methods in order to map quantitative trait loci (QTLs) with .SSR, RAPD and RFLP. The main results are as follows:1 Comparison of identification resistance methods1 . 1 The resistance of rapeseed seedling stage was evaluated by placing mycelial plugs, infested wheat seeds and rapeseed leave.s on detached leaves, immersing petolies into oxalic acid solution and placing mycelial plugs on leaves in vivo. The lesion length was significantly different among 3 detached leaves inoculation methods, which were effectively to identify resistant and susceptible plants at 48h and 72h. Disease of leaves in vivo developed faster than detached ones. There was distinguished correlation between detached leaves mycelial plugs inoculation method and oxalic acid-submerged petolies method.1 .2 The resistance of rapeseed maturing stage was evaluated by placing mycelial petals, plugs and toothpicks on axilla to induce stems disease, spraying whole plants with mycelial suspension and inducing disease in disease garden. To compare disease development showed that lesion length increased steadily every day from 9d to 19d and 5d to 12d with mycelial petals and plugs inoculations respectively, but increased linearly with mycelial toothpicks. There were significantly canonical correlations between disease garden evaluation and mycelial petals inoculation methods, mycelial plugs and petals inoculation methods, mycelial plugs and toothpicks inoculation methods, as well as disease garden evaluation and mycelial petals inoculation methods across 2002 to 2003.1.3 There was significant canonical correlation between partial resistance criterions of seedling and maturing stages, but seedling resistance cannot entirely represent maturing resistance.1.4 Westar and Hui 5200 were highly susceptible and zhongyou 821 was most steadily and reliably resistant among 12 varieties or lines.2 Genetic analysis of resistance of Brassica nap us to Sclerotinia sclerotiorum2.1 Inheritance of resistance in cross of DH821 DHBao604 by joint analysis ofmulti-generations (P1, P2, F1, BC1, BC2, F2) was mainly controlled by 2 major genes, sometimes mixed with the effect of polygenes. Dominant effect and associated espistatic interaction were important for resistance.2.2 Inheritance of resistance in the same cross as above by analyzing DH population was controlled by polygenes at seedling and maturing stages.3 Mapping of resistant genes to Sclerotinia sclerotiorum in B.napus3.1 There were 81 QTLs associated resistance by ANOVA at the significant level (P< 0.05), among them 20, 20, 30, 14, 20 for seedling resistance, maturing resistance evaluated by disease garden and mycelial petals inoculum in 2002, and mycelial toothpicks and petals inoculations in 2003 respectively.3.2 Nineteen QTLs for resistance were detected by...
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