1.State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory for Vegetable Germplasm Enhancement and Utilization of Hebei/Collaborative Innovation Center of Vegetable Industry in Heibei/College of Horticulture, Hebei Agricultural University;2.Guoyan seed Co Ltd of Hebei Province
Introduction of Foreign Intellectual Projects in Hebei Province(2019YX023A)，Hebei Innovation Capability Improvement Plan Project (20592901D)，Hebei Province
Clubroot disease is one of the most important diseases of Chinese cabbage and other cruciferous crops. Identification of new clubroot resistant resources is of importance in breeding for resistant varieties to effectively prevent the occurrence. In this study, two resistant and two susceptible inbred lines of Chinese cabbage, respectively, were used to identify the polymorphic markers that are closely linked to the CR genes of the resistant inbred lines. Sixty-three turnip germplasms were tested for resistance at the seedling stage by inoculation using the bacterium Plasmodiophora brassicae isolates from Wulong district of Chongqing municipality and Tangshan city of Hebei province. The turnip germplasms showing resistant or tolerant were genotyped using molecular markers linked to CR genes. Based on 20 tested markers, two were found to be linked to the resistance gene CRa, one marker linked to CRb, five markers linked to CRbkato and one marker linked to CRd. Six turnip germplasms showing good resistance simultaneously to isolates were collected from Centre for Genetic Resources (CGN), Netherlands, including three forage turnips and three vegetable turnips originally from European countries. The genotyping results also suggested a heterozygous status in the genetic background of these turnips. The germplasms CGN1, CGN10 and CGN11 were found harboring four CR loci (CRa, CRbkato, CRb and CRd), CGN23 and CGN36 were detected harboring three loci (CRa, CRbkato and CRd), and CGN30 carried two CR loci (CRa and CRbkato). Whether these turnip germplasms host additional CR loci still remains to be further investigated. Collectively, these results provided materials for mining new CR genes and breeding new CR varieties of Chinese cabbage and other cruciferous crops.