Transcription factor MaAP-1 regulates conidiation patterns via YAP domain binding to the MaPom1 promoter in Metarhizium acridum: Implications for enhancing fungal biocontrol efficiency.

Entomopathogenic fungi such as Metarhizium acridum are pivotal for sustainable pest management, yet the industrial conidial production is hindered by low yields and environmental sensitivity. Transcriptional regulation provides key targets for engineering strain modification. AP-1 transcription factors (TFs) are well-known for their roles in fungal growth, development, conidiation, pathogenicity and stress tolerance across various fungi. However, the structural and functional roles of AP-1 TF and its regulatory mechanisms in conidiation pattern shift (CPS) remain unexplored in M. acridum. In this study, MaAP-1 was identified as a nuclear-localized transcription factor. Deletion of MaAP-1 or its YAP domain accelerated conidial germination, increased conidial yields, impaired stress tolerance, and reduced pathogenicity. MaAP-1 also served as a regulator of conidiation pattern shift (CPS), shifting microcycle conidiation (MC) to normal conidiation (NC) on SYA medium. Yeast one-hybrid (Y1H) and electrophoretic mobility shift assays (EMSA) revealed that the YAP domain of MaAP-1 directly bound to the motif (TTAGTAA/TTACTAA) in the MaPom1 promoter to regulate CPS, and molecular docking predicted the critical residues (ILE-210, THR-211, THR-212, Glu-213, Gln-216, LYS-218) in YAP domain to mediate this process. Overall, these findings highlight roles of MaAP-1 and its domain in conidial development, stress resistance, pathogenicity, CPS and provide novel insights into the molecular mechanisms underlying CPS. This work lays a theoretical foundation for strain improvement and fungal pesticide optimization to meet the demands of sustainable agricultural development.