Abstract
Sclerotinia sclerotiorum, a devastating phytopathogenic fungus with global distribution, exhibits a broad host range encompassing over 700 plant species. Sclerotinia stem rot caused by this pathogen poses a significant threat to sustainable oilseed rape production. Coniothyrium minitans, a mycoparasite of S. sclerotiorum, is a promising biological control agent against this devastating disease. C. minitans-based formulations have been commercially developed for field application. A transcriptomic analysis revealed significant upregulation of the chitinase-encoding gene CmCH1 in C. minitans during interaction with S. sclerotiorum. Knockout of either CmCH1 or another chitinase-encoding gene CmCH10 in C. minitans did not markedly affect the mycelial growth, development, and parasitism of S. sclerotiorum. However, knockout CmCH1 and CmCH10 simultaneously resulted in reduced growth rate, impaired protoplast release, enhanced cell wall integrity, and diminished mycoparasitic capability. These results indicate that CmCH1 and CmCH10 collectively influence remodeling of the cell wall in C. minitans and its mycoparasitic activity.