Two Clubroot-Resistance Genes, and , Mapped in Using Bulk Segregant RNA Sequencing.

Genetic resistance is widely used to manage clubroot () in brassica crops, but new pathotypes have recently been identified on canola () on the Canadian prairies. Resistance effective against both the most prevalent pathotype (3H, based on the Canadian Clubroot Differential system) and the new pathotypes is needed. BC plants of from a cross of line 96-6990-2 (clubroot resistance originating from turnip cultivar 'Waaslander') and a susceptible doubled-haploid line, ACDC, exhibited a 1:1 segregation for resistance against pathotypes 3H and 5X. A resistance gene designated as was mapped initially based on the percentage of polymorphic variants using bulked segregant RNA sequencing (BSR-Seq) and further mapped using Kompetitive Allele Specific PCR. DNA variants were identified by assembling short reads against a reference genome of . was mapped into chromosome A08. It was flanked by single nucleotide polymorphisms (SNP) markers (A90_A08_SNP_M12 and M16) between 10.00 and 10.23 Mb, in an interval of 231.6 Kb. There were 32 genes in the interval. Three genes (, , and ) were annotated with disease resistance mechanisms, which are potential candidates for . Another resistance gene, designated as for resistance to pathotype 5X was mapped, with the flanking markers (A90_A08_SNP_M28 and M79) between 10.85 and 11.17 Mb using the SNP sites identified through BSR-Seq for . There were 44 genes in the interval, three of which () were annotated as immune-system-process related genes, which are potential candidates for .