Physiological and transcriptomic analyses reveal the antifungal activity of Simplicillium lanosoniveum filtrate against wheat crown rot pathogen Fusarium pseudograminearum.

Fusarium pseudograminearum (Fp), the predominant phytopathogen responsible for wheat crown rot, severely impairs wheat growth and yield, posing a persistent threat to global wheat production. This study evaluated the biocontrol potential of the fermentation filtrate from the endophytic fungus Simplicillium lanosoniveum FSL-376 against Fp. In vitro, the filtrate exhibited potent antifungal activity, significantly inhibiting mycelial growth, and causing severe morphological abnormalities in both hyphae and spores at low concentrations. Mechanistic investigations revealed that the antifungal action was achieved by disrupting fungal cell membrane integrity [evidenced by increased electrolyte conductivity and malondialdehyde (MDA) accumulation], triggering intense oxidative stress via suppressing the activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and disrupting energy metabolism through the inhibition of hexokinase (HK) and succinate dehydrogenase (SDH) activities. Transcriptomic analysis further revealed multi-target inhibition, characterized by the downregulation of genes involved in transmembrane transport, antioxidant defense, and oxidative phosphorylation. In pot experiments, seed treatment with the FSL-376 filtrate significantly alleviated Fp-induced growth inhibition, restored antioxidant enzyme activities and chlorophyll content in wheat seedlings, and improved root morphology. Notably, the FSL-376 filtrate exhibited no phytotoxicity to wheat seedlings and showed no growth-promoting effect under pathogen-free conditions, indicating its biosafety and pathogen-specific biocontrol efficacy. This study demonstrates that S. lanosoniveum FSL-376 serves as a promising and reliable biocontrol resource for wheat crown rot management, which functions via dual mechanisms of direct antifungal inhibition and enhancement of host plant stress tolerance.