Phylogenetic Diversity, Pathogenicity and Host Range of Verticillium longisporum and V. dahliae Associated with Verticillium Wilt of Chinese Cabbage in Korea.

Verticillium wilt, caused by Verticillium dahliae and V. longisporum, has emerged as a serious threat to Chinese cabbage production in Korea. To clarify the population structure, pathogenicity, and host range of these pathogens, we collected 60 isolates from major Chinese cabbage-growing regions and conducted multilocus phylogenetic analyses based on five nuclear genes. Pathogenicity assays were carried out on Chinese cabbage, and host range assays were conducted on diverse crops. The results showed that V. longisporum lineage A1/D1, the predominant lineage in Europe and North America, dominated across all surveyed regions, while a single A1/D3 lineage isolate was detected for the first time in Korea. Pathogenicity tests demonstrated that V. longisporum was generally more aggressive on Chinese cabbage than V. dahliae, with the A1/D3 isolate displaying the highest virulence among all isolates tested. Host range assays revealed that V. longisporum was restricted to cruciferous crops, whereas V. dahliae infected crucifers as well as solanaceous and several other crops, indicating broader epidemiological risks. Non-host crops such as barley, buckwheat, carrot, maize, and sudangrass were not infected by either species, suggesting their potential use in crop rotation. Collectively, these findings demonstrate that V. longisporum, particularly lineage A1/D1, is the major causal agent of Verticillium wilt epidemics in Korean Chinese cabbage production. The detection of aggressive A1/D3 lineage and genetically diverse V. dahliae populations underscores additional long-term risks that necessitate continuous monitoring, resistance breeding, and integrated disease management.