Fine mapping of a novel resistance gene to clubroot disease in Brassica oleracea through bulked segregant RNA sequencing
A. DAKOURI (1), X. Zhang (2), G. Peng (3), B. Gossen (3), K. Falk (3), F. Yu (3) (1) Agriculture and Afri-Food Canada, Canada; (2) Agricluture and Agri-Food Canada, Canada; (3) Agriculture and Agri-Food Canada, Canada

Clubroot, caused by Plasmodiophora brassicae, is a major disease of Brassica oleracea (cabbage, kale etc.), B. napus (canola) and other Brassica spp. crops worldwide. Genetic resistance is a cost-effective method to manage the disease. The cabbage cultivar Tekila was found to be highly resistant to several pathotypes of P. brassicae in western Canada. To introgress the clubroot resistance (CR) into canola, we initiated the identification and mapping of CR gene(s) in this resistant cultivar. A cross was made between Tekila and a susceptible Chinese kale (B. oleracea) line T010000DH3 to make a segregating population, from which a single dominant resistance gene, Rcr7, was identified. A combination of bulk segregant analysis and RNA sequencing was used to map Rcr7; Illumina RNA sequencing was performed on bulked resistant and susceptible samples derived from the segregating population. A total of 309,363 SNPs were detected, of which 14,583 unique SNPs were mapped to the resistant bulk. Chromosome C7 carried the highest number of unique SNPs (23%) compared to 7-14% on each of the remaining individual 8 chromosomes. SNPs were most abundant between 40 to 43 Mb on chromosome C7, indicating that Rcr7 is likely located in this region. The association of Rcr7 with 48 SNPs in the target region was confirmed using the Kompetitive Allele-Specific PCR method. Rcr7 was flanked by the SNP markers C7-SNP-44 and C7-SNP-56, which span an interval of 0.2 Mb and co-segregated with three SNP markers (C7-SNP-34, 43 and 68) in a segregating population consisting of 326 plants. Four genes encoding TIR-NBS-LRR proteins were identified in the target region, representing possible candidates for Rcr7. The SNP markers developed in this study can be used in marker-assisted selection for resistance to clubroot in breeding programs.

Abstract Number: P11-349
Session Type: Poster