The Gβ-like protein FgCpc2 is indispensable for the development, pathogenicity, and toxisome formation in Fusarium graminearum

Abstract Fusarium head blight caused by Fusarium graminearum is a serious disease that affects cereal crops worldwide, leading to significant yield losses. The Gβ-like protein Cpc2 has been documented as a key regulator of growth, development, and virulence in pathogenic fungi such as Cryptococcus neoformans and Aspergillus fumigatus . However, the specific biological functions of its ortholog, FgCpc2, in F. graminearum remain unexplored. Phylogenetic analysis reveals that FgCpc2 is highly conserved across various species and shares notable amino acid sequence similarity with Gβ-like proteins. Using the gene deletion approach, we found that FgCpc2 is critical for vegetative growth, conidiation, and sexual development in F. graminearum . The Δ Fgcpc2 mutant showed increased sensitivity to a range of stress factors, including osmotic, oxidative, and cell wall-disrupting agents. Furthermore, FgCpc2 is central to the pathogenicity of F. graminearum , as the Δ Fgcpc2 mutant exhibits reduced disease symptoms on wheat coleoptiles and flowering heads. Importantly, FgCpc2 is required for deoxynivalenol (DON) production, as the Δ FgCpc2 mutants produce significantly fewer toxisomes compared to the wild type. Transcriptomic analysis showed that FgCpc2 affects mycelial growth by regulating amino acid metabolism, the biosynthesis of secondary metabolites ( TRI gene family) and ABC transporters. Subcellular localization experiments revealed that FgCpc2 is uniformly distributed in the cytoplasm throughout different stages of fungal development. Overall, these findings highlight the crucial roles of FgCpc2 and lay a foundation for developing targeted strategies against Fusarium head blight.