Mapping quantitative trait loci (QTL) for clubroot resistance in Brassica rapa L.

SummaryThe genes related to clubroot resistance (CR) from a new genetic resource of European turnip (Brassica rapa ssp. rapifera) were identified, and their chromosomal locations were determined using quantitative trait loci (QTL) analysis. One hundred and ninety F2 plants derived from a cross between a clubroot-resistant inbred turnip line (IT033820) and a susceptible inbred Chinese cabbage (B. rapa ssp. pekinensis) line (BP079) were used to construct a genetic linkage map. The map contained 477 markers, including 401 amplified fragment length polymorphism (AFLP) and 56 simple sequence repeat (SSR) markers, in ten linkage groups (LGs). It covered a total length of 1,149.1 cM, with an average interval of 2.53 cM between markers. The majority of individual F2 plants were found to be highly resistant to clubroot disease based on phenotypic evaluations following inoculation with race 4 of Plasmodiophora brassicae. Using composite interval mapping analysis, two major QTLs (Pb-Br3 and Pb-Br8) and one minor QTL...