Developing near-isogenic brassica napus lines for differentiating pathotypes of plasmodiophora brassicae
To develop germplasm of ten canola lines, each with a single unique resistance gene to clubroot pathotypes. The research will also focus on validation of markers for the identification of clubroot resistant genes with different modes of action in canola.
Clubroot disease, caused by Plasmodiophora brassicae, poses a serious threat to canola production in western Canada. Several research groups have classified P. brassicae into various pathotypes based on differential reactions on Brassica cultivars. However, most of the differential cultivars used by the researchers are non-canola crops that belong to vegetable or fodder Brassicas. Ideally, a set of near-isogenic spring canola lines containing single clubroot resistance genes should be developed, which could then be used to differentiate races of P. brassicae. In addition, this set of canola lines could be used for monitoring changes in the pathogen populations in canola fields. Genetic mapping has identified 10 genes for clubroot resistance that occur in Brassica rapa. In this project, we aimed to develop a set of differential lines of spring type B. napus with single genes for identification of races of P. brassicae and for durable resistance to clubroot. B. rapa resistant donors containning Rcr1, Rcr2, Crr1 to Crr4, CRa, CRb, CRc and CRk and a B. napus cultivar containning clubroot resistance gene RcrM were crossed with susceptible spring type canola line DH16516 respectively and the resulting F1 plants were crossed into the susceptible background to back cross generations 3 to 4 (BC3 to BC4). SNP markers linked to most of the clubroot resistance genes were validated. Molecular marker assisted selcted was performed each generation. Plants were tested with two Canadian pathotypes (3 and 5X) of P. brassicae. Homozygous lines containing Rcr1 or Rcr2 in BC4 were obtained. Plants containing the rest of CR genes in BC3 were developed . Microspore culture is being performed for developing homozygous lines carrying the rest of the CR genes.