The non-ribosomal peptide synthetase_C mediates abiotic stress tolerance and modulates DNA damage responses in Metarhizium anisopliae.

BACKGROUND: Abiotic stresses are a major limitation to the efficacy of entomopathogenic fungi in natural ecosystems and in biocontrol applications, yet the mechanisms that confer stress tolerance in Metarhizium anisopliae remain poorly understood. Non-ribosomal peptide synthetases (NRPSs) are key enzymes involved in fungal secondary metabolism and stress responses. RESULTS: We examined the function of the non-ribosomal peptide synthetase condensation domain in M. anisopliae (MaNRPS_C) by constructing a deletion mutant (ΔMaNRPS_C), an overexpression strain (OE), and compared them with the wild type (WT). Deletion of MaNRPS_C did not affect pathogenicity toward Sogatella furcifera or Locusta migratoria manilensis, but it markedly reduced conidial germination, sporulation, and tolerance to ultraviolet-B (UV-B) radiation, heat stress, and several chemical stressors. Conversely, the OE strain displayed faster germination, higher conidial yields, and enhanced resistance to these abiotic challenges. Furthermore, MaNRPS_C positively regulated the expression of melanin-biosynthesis genes, resulting in increased pigment accumulation that protected conidia from UV-B-induced damage. In addition, MaNRPS_C upregulated key DNA repair genes (e.g., rad3, rad10) and heat-shock protein genes (e.g., hsp40, hsp70), suggesting enhanced DNA repair capacity and protein homeostasis under stress conditions. CONCLUSION: These results identify MaNRPS_C as a key regulator of abiotic stress tolerance, particularly under UV-B and heat stress in M. anisopliae. Targeted manipulation of this gene may facilitate the development of more robust fungal biopesticides with improved field performance. © 2026 Society of Chemical Industry.