Mapping-Based Localization of Blackleg-Resistant Candidate Genes of Chinese Cabbage (Brassica rapa)

Recently, blackleg disease has seriously impacted the cultivation and development of Brassica crops. In this study, we conducted mapping-based localization of blackleg-resistant candidate genes in Chinese cabbage. Through phenotype evaluation, Chinese cabbage materials 15S414 and 15S420 were selected as blackleg-resistant and blackleg-susceptible parents, respectively. Inheritance pattern analysis suggested that the dominant major genes mainly determined the blackleg resistance of Chinese cabbage. Upon bulked segregant analysis, the blackleg-resistant candidate genes were initially located within a 4.3-Mb interval on chromosome A06. Through construction of the genetic linkage map, blackleg-resistant candidate genes were further limited to a region of 160 kb containing seven resistance-related genes. Coding sequence variation analysis revealed that all seven resistance-related genes displayed various degrees of single nucleotide polymorphism variations between the parent materials 15S414 and 15S420.