EXPLORING LOCI AND FUNCTIONAL GENES INVOLVING SCLEROTINIA RESISTANCE IN BRASSICA NAPUS

National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, P. R. China

Sclerotinia stem rot is the most devastating disease of Brassica napus in China. QTLs involved in resistance to Sclerotinia were detected in a rapeseed population of F2:3 families derived from a cross between H5200 and a resistant line Ning RS-1. Resistance was assessed at seedling stage and mature plant stage. Thirteen loci were identified by one-way ANOVA and six QTLs were detected with MapMaker-QTL. We found that three of the six QTLs were associated with leaf resistance at seedling stage and collectively accounted for 40.7% of the total phenotypic variation, each accounting for 23.2%, 16.6%, and 13.6% respectively. Three QTLs were found corresponding to the disease resistance at mature plant stage, explaining 49.0% of the phenotypic variation. Epistasis was observed for the two measurements of resistance. Functional genes involving Sclerotinia resistance in B. napus were explored using Arabidopsis resources as a platform. cDNA chips of 9.2K Arabidopsis were used to hybridize with cy3/cy5 labeled cDNAs of NingRS-1which was challenged by Sclerotinia. A set of genes was found to be associated with Sclerotinia resistance. The primary result shown that the positive genes involved cell wall strengthening genes, antimicrobial genes, genes involving programmed cell death, genes encoding transcript factors and zinc finger proteins. Some of the functional genes have been confirmed by hybridized the cDNAs of B. napus with nylon membranes arrayed with the inserts of Arabidopsis cDNA library. Some of the functional genes will be mapped using a recombinant inbreed lines derived from the F2:3 population of Ning RS-1/H5200.