VdGGCT, a GGCT-like superfamily protein, is required for mycelial growth, conidiation, and pathogenicity of Verticillium dahliae

Abstract Given the scarcity of known virulence factors in Verticillium dahliae , a fungus that causes severe agricultural losses worldwide, identifying novel virulence genes is essential for understanding its pathogenic mechanisms and ultimately for developing effective disease control strategies. Gamma-glutamyl cyclotransferase (GGCT) has been recognized as a promising drug target, yet its biological functions and regulatory roles in plant-pathogenic fungi remain largely unexplored. Here, we demonstrate that knockout of the VdGGCT gene severely attenuates the development and virulence of V. dahliae and increases resistance to diamide (Dia)-induced oxidative stress. Functional assays using the organic sulfur auxotrophic yeast mutant ABC1723 revealed that despite belonging to the GGCT superfamily, VdGGCT does not exhibit detectable GGCT activity towards GSH, γ-Glu-Met, or γ-Glu-Cys. Integrative transcriptomic and metabolomic analyses revealed that the deletion of VdGGCT significantly downregulated the expression of glutamate and γ-glutamyl amino acids in the γ-glutamyl cycle, with concordant dysregulation of arginine/proline and beta-alanine metabolism at both levels, indicating that VdGGCT modulates the expression and abundance of genes related to pathogenicity, especially in the γ-glutamyl cycle and amino acid metabolism pathways. Collectively, these findings highlight the importance of VdGGCT in the development, oxidative stress response, and virulence of V. dahliae , identifying it as a novel potential target for designing innovative fungicides.