Fine Mapping of Clubroot Resistance Loci and Candidate Gene Analysis in Chinese Cabbage ( L.).

Clubroot is caused by , which threatens crop production worldwide. In recent years, there has been an outbreak and rapid spread of clubroot in many major cruciferous crop-producing areas of China. In this study, we identified a cabbage material DingWen (DW) with different resistant capabilities from Huashuang5R (H5R) and Huayouza62R of , which are currently used as the main resistant cultivars for clubroot management in China. We used a next-generation sequencing-based bulked segregant analysis approach, combined with genetic mapping to identify clubroot-resistant (CR) genes from F population generated from a cross between the DW (CR) and HZSX (clubroot susceptible). The CR locus of DW (named ) was mapped to a region between markers A08-4346 and A08-4853, which contains two different loci and after fine mapping. The loci contain a fragment of 395 kb between markers A08-4624 and A08-4853 on A08 chromosome, and it is responsible for the resistance to and isolates. However, together with , corresponding to a 765-kb region between markers A08-4346 and A08-4624, then it can confer resistance to . Finally, through expression analysis between resistant and susceptible materials, two genes encoding TIR-NBS-LRR proteins ( and ) and one gene encoding an RLP protein () were identified to be the most likely CR candidates for the peculiar resistance in DW.