From isolation to application: Characterization of Talaromyces purpureogenus TS as a biocontrol agent against Verticillium wilt.

Verticillium wilt, caused by Verticillium dahliae Kleb., is a destructive vascular disease that is difficult to control using chemical fungicides and remains a major challenge in plant disease management. Microbial biocontrol represents a sustainable alternative, and the identification of highly antagonistic strains against V. dahliae is of considerable importance. In this study, a strain of Talaromyces purpureogenus TS, which demonstrated strong antagonistic and mycoparasitic activity against V. dahliae, was isolated from soil. Its cell-free supernatant inhibited the growth of V. dahliae by disrupting the cell membrane, suggesting potential disorders in material and energy metabolism, as indicated by transcriptomic analysis; but showed no significant effect on the tested strains of Fusarium graminearum, Fusarium oxysporum and Saccharomyces cerevisiae under the conditions tested. Furthermore, the cell-free supernatant also exhibited broad-spectrum antibacterial properties. Compared to the biocontrol fungus Beauveria bassiana, T. purpureogenus TS exhibited stronger antagonistic activity against V. dahliae, along with higher conidial yield and stress tolerance. Furthermore, pre-inoculating of cotton plants with T. purpureogenus TS reduced disease symptoms and fungal colonization in cotton plants, indicating a protective effect. These results are expected to deepen the understanding of the characteristics of of T. purpureogenus, more importantly, the obtained strain has the potential to promote the development of biological control strategies against V. dahliae.