Improving cabbage resistance to Sclerotinia sclerotiorum via crosses with Brassica incana

Cabbage is a widely cultivated leafy vegetable, but head rot disease caused by the fungus Sclerotina sclerotiorum can seriously reduce its yield and quality. There are currently not any cabbage varieties that are completely immune to the disease, but its wild relative Brassica incana is very resistant. In this study, cabbage resistance was improved by backcrossing a highly resistant B. incana accession (C01) with a susceptible cabbage cultivar (F416). Although C01 lacks a leafy head formation, highly resistant plants appeared in the fourth backcrossing generation (BC₄F₁) that had a similar leafy head to F416. The individuals with strong resistance were purified by self-pollination. Inbred lines that maintained a relatively stable resistance at BC₄F₃ were developed and had significantly higher resistance to S. sclerotiorum than F416. In addition, hybrids created from a cross between of BC₄F₃ and E2 had higher resistances to S. sclerotiorum and similar agronomic characteristics to Xiyuan 4. The results demonstrated that new F416 lines that are resistant to S. sclerotiorum can be developed, and that these lines could be used to create new cabbage varieties with superior head rot resistance.