Identification of common QTL for resistance to Sclerotinia sclerotiorum in three doubled haploid populations of Brassica napus (L.)

Sclerotinia stem rot (SR) is one of the most devastating diseases of canola/rapeseed. Quantitative trait loci (QTL) analyses were carried out to identify loci responsible for resistance to SR in three doubled haploid DH populations (H1, H2 and H3). Petiole inoculation technique PIT was used to evaluate the all populations for resistance to SR. Genetic maps were developed using sequence related amplified polymorphism SRAP and simple sequence repeat SSR markers. Genetic maps of the H1 and H2 populations were developed using 508 and 478 markers, respectively. Previously published genetic map of the H3 population was also used in this study. The QTL analysis was carried out for each replicate separately as well as on the average of all the replicates. The numbers of identified QTL in each analysis varied from four to six in the H1 population, three to six in the H2 population and two to six in the H3 population. A number of common QTL were identified between the replicates of each population. Two common QTL were identified on linkage group A7 and C6 between the H1 and H3 populations and one QTL on A9 between the H2 and H3 populations. We are the first to report, identification of common QTL between different populations of Brassica napus.