ApCtf1β-Interacting Target Proteins BDPH1 and BDEUL12 Regulate Pathogenicity in Arthrinium phaeospermum

Arthrinium phaeospermum is the primary pathogen responsible for shoot blight disease in Bambusa pervariabilis × Dendrocalamopsis grandis. Previous research identified ApCtf1β, a key gene involved in pathogenicity encoding a cutinase transcription factor involved in pathogenicity, as essential for infecting hybrid bamboo. However, the interacting target proteins and functions of ApCtf1β within the fungus remain unclear, limiting the comprehensive understanding of A. phaeospermum's pathogenic pathways. Therefore, this study employed yeast two-hybrid, luciferase protein complementation, and GST pull-down assays to detect and confirm ApCtf1β-interacting proteins BDPH1 and BDEUL12. Further bioinformatics analyses of these proteins were conducted. Using Agrobacterium-mediated fungal genetic transformation, we generated BDPH1 and BDEUL12 overexpression transformants, gene-silenced transformants, as well as Apctf1β-BDPH1 and Apctf1β-BDEUL12 co-expression transformants. Functional studies of these interacting proteins were performed at different developmental stages, examining gene expression, hyphal growth rate, spore production, chemical susceptibility, pathogenicity and ubiquitination function. The results indicated that BDPH1 and BDEUL12 are closely associated with the virulence of A. phaeospermum, with the BDEUL12 gene exerting a more potent effect on virulence. This study provides a foundation for further elucidating the molecular mechanisms underlying the pathogenicity of A. phaeospermum.