Biocontrol activity and antifungal mechanisms of volatile organic compounds produced by Trichoderma asperellumXY101 against pear Valsa canker

Abstract BACKGROUND Synthetic fungicides raise environmental and health concerns, and microorganisms are emerging as promising natural antagonists in plant protection. This study evaluated strain XY101 and its volatile organic compounds (VOCs) as biocontrol agents against pear Valsa canker caused by Vasal pyri , aiming to identify the antifungal mechanisms and key compounds. RESULTS The biocontrol fungus was identified as Trichoderma asperellum . Trichoderma asperellum XY101 strongly suppressed the mycelial growth of Vasal pyri on culture plates. A colonization assay indicated that the VOCs produced by T . asperellum XY101 significantly reduced the pathogenicity of Vasal pyri on detached pear twigs, with an inhibition rate of 78.96%. Scanning electron microscopy (SEM) and laser confocal microscopy revealed that VOCs produced by T . asperellum XY101 caused abnormal changes in mycelial ultrastructure and damaged the integrity of fungal cell membrane. The results of headspace solid‐phase microextraction‐gas chromatography–mass spectrometry (HS‐SPME‐GC–MS) analysis showed the detection of 24 possible VOCs produced by strain XY101, with 3,7‐dimethyl‐1‐octanol and 1‐octen‐3‐ol identified as the primary antagonistic VOCs affecting pear Valsa canker. Transcriptome analysis demonstrated that these VOCs modulated gene expression in pathogenic fungal strains related to metabolism, membrane damage, pathogenicity, and resistance. CONCLUSION Trichoderma asperellum XY101 and its VOCs, 3,7‐dimethyl‐1‐octanol and 1‐octen‐3‐ol, showed effective inhibitory effects against Vasal pyri , providing a basis for the development of VOCs‐based biological fumigants to manage pear Valsa canker. © 2025 Society of Chemical Industry.