Marker-Assisted Pyramiding of and Genes to Improve the Clubroot Resistance of .

Clubroot, caused by , is an economically important soil-borne disease that threatens Brassicaceae crops worldwide. In recent years, the incidence area of Chinese cabbage ( ssp. ) clubroot disease has increased, which severely affects the yield and quality of Chinese cabbage. The resistance of varieties harboring the single clubroot-resistance (CR) gene is easily broken through by pathotypes. and , genetically identified in , are CR genes known to be highly resistant to different pathotypes. In our study, we perform the gene pyramiding of and in Chinese cabbages through marker-assisted selection (MAS), and develop homozygous pyramided lines. The newly generated pyramided lines exhibit greater resistance to six different pathotypes than that of two parental lines carrying a single CR gene. This study provides new CR-gene-pyramided lines for the development of clubroot-resistant Brassica varieties for future breeding programs.