Identification and Functional Analysis of a Novel Hydrophobic Protein VdHP1 from Verticillium dahliae.

Verticillium dahliae could cause destructive vascular wilt disease on hundreds of plant species around the world, including cotton. In this study, we characterized the function of a hydrophobin gene in pathogen development and pathogenicity. Results showed that could induce cell death and activate plant immune responses. The deletion mutants () and the complement mutants () were obtained by the homologous recombination method. The deletion mutants exhibited increased hydrophilicity, inhibited microsclerotial formation, and reduced spore smoothness. In addition, the deletion mutants were more sensitive to NaCl, while relatively insensitive to KCl and sorbitol. Mutants also had greater resistance to Congo red, UV radiation, and high temperature, which suggested that strains have stronger resistance to abiotic stress in general. Different carbon source assays showed that the utilization ability of skim milk, cellulose, and starch was greatly enhanced in , compared with that of WT and complemented strains. Furthermore, did not affect mycelium penetration on cellophane but contributed to mycelium growth on surface of the living plant cells. The pathogenicity test found that the crude toxin content, colonization, and dispersal of was significantly increased compared with the WT and complementary strains. In addition, cotton seedlings showed more severe wilting symptoms after inoculation with strains. These results suggested that the hydrophobin negatively regulated the virulence of V. dahliae, and played an important role in development, adaptability, and pathogenicity in V. dahliae, which maybe provide a new viewpoint to further understand the molecular mechanisms of pathogen virulence. Verticillium dahliae is a soilborne fungal pathogen that causes a destructive vascular disease on a large number of plant hosts, resulting in great threat to agricultural production. In this study, it was illustrated that the hydrophobin VdHP1 could induce cell death and activate plant immune responses. VdHP1 affected the hydrophobicity of V. dahliae, and negatively regulated the strains resistant to stress, and the utilization ability of different carbon sources. In addition, VdHP1 did not affect mycelium penetration on cellophane but contributed to mycelium growth on surface of the living plant cells. The gene negatively regulated the total virulence, colonization, and dispersal of V. dahliae, with enhanced pathogenicity of mutant strains in this gene. These results suggested that the hydrophobin VdHP1 played an importance in development, adaptability, and pathogenicity in V. dahliae, and would provide a new viewpoint to further understand the molecular mechanisms of pathogen virulence.