Identification of QTLs for Resistance to 10 Pathotypes of Plasmodiophora Brassicae in Brassica Oleracea Cultivar ECD11 Through Genotyping-by-sequencing.

Two major quantitative trait loci (QTLs) and five minor QTLs for 10 pathotypes were identified on chromosomes C01, C03, C04 and C08 through genotyping-by-sequencing from Brassica oleracea. Clubroot caused by Plasmodiophora brassicae is an important disease in brassica crops. Managing clubroot disease of canola on the Canadian prairie is challenging due to the continuous emergence of new pathotypes. Brassica oleracea is considered a major source of quantitative resistance to clubroot. Genotyping-by-sequencing (GBS) was performed in the parental lines; T010000DH3 (susceptible), ECD11 (resistant) and 124 BC1 plants. A total of 4769 high-quality polymorphic SNP loci were obtained and distributed on 9 chromosomes of B. oleracea. Evaluation of 124 BC1S1 lines for resistance to 10 pathotypes: 3A, 2B, 5C, 3D, 5G, 3H, 8J, 5K, 5L and 3O of P. brassicae, was carried out. Seven QTLs, 5 originating from ECD11 and 2 from T010000DH3, were detected. One major QTL designated as Rcr_C03-1 on C03 contributed 16.0–65.6