K404 Acetylation of Glutamate Dehydrogenase CrGdh2 Is Necessary for Mycoparasitism of <i>Clonostachys chloroleuca</i> against <i>Sclerotinia sclerotiorum</i>

<i>Clonostachys chloroleuca</i> is a potential biocontrol fungus capable of parasitizing various plant fungal pathogens. In the highly efficient strain 67-1, we identified a glutamate dehydrogenase gene, <i>CrGdh2</i>, during mycoparasitization of <i>Sclerotinia sclerotiorum. CrGdh2</i> is essential for the biocontrol activity of <i>C. chloroleuca</i>, as its deletion compromised control efficacy against <i>Sclerotinia</i> rot and tomato root rot by 27.9% and 39.8%, respectively, compared to the wild-type strain. Acetylated CrGdh2 was investigated using acetylation and deacetylation mimetic mutants. The results showed that when strains were inoculated on <i>S. sclerotiorum</i> sclerotia, no obvious infection structures were detected in ΔCrGdh2 and ΔCrGdh2-C^K404R. In pot experiments, both mutants also showed over 30% reduction in biocontrol efficacy, in contrast to the wild-type and ΔCrGdh2-C^K404Q strains, indicating the essential role of K404 acetylation. The findings reveal the roles of glutamate dehydrogenase and its acetylation in mycoparasitism, providing novel insight into the biocontrol mechanisms of <i>C. chloroleuca</i>.