Identification of Candidate Genes for Clubroot-Resistance in Brassica oleracea using QTL-Seq

Abstract

Clubroot caused by Plasmodiophora brassicae is a devastating disease of cabbage (Brassica oleracea). To identify quantitative trait loci (QTLs) for clubroot resistance (CR) in B. oleracea, genomic resequencing was carried out in two sets of extreme pools that constructed from 184 F2 cloned-lines derived from cross between clubroot-resistant cabbage ‘GZ87’ (against race 4) and susceptible cabbage ‘263’. QTL-seq analyses identified one CR QTL from group I on chromosome C07 and four QTLs from group II on C04 and C07, among which three QTLs of C07 that found from group II were located within the one detected from group I. RNA-Seq and qRT-PCR were conducted in the extreme pools of group II before and after inoculation identified two potential candidate genes (Bol037115 and Bol042270) from the three QTLs interval on C07, which exhibiting up-regulation after inoculation in the resistant pool but down-regulation in the susceptible pool. A functional marker ‘SWU-OA’ was developed from one QTL on C07, exhibiting ~95% accuracy in identifying CR in 56 F2 lines. Our study will provide valuable information on digging resistance genes against P. brassicae and may accelerate breeding process of B. oleracea with CR.Key Message QTLs and potential candidate genes for clubroot resistance were identified in Brassica oleracea