Butyric acid derived from Pantoea ananatis CE26 suppresses postharvest gray mold by inducing membrane disruption and oxidative stress of Botrytis cinerea

The gray mold fungus, Botrytis cinerea , is a major fungal pathogen responsible for postharvest decay of fruit. Biocontrol agents are increasingly recognized as sustainable strategies for managing postharvest diseases due to their environmental compatibility and strong antifungal activity. In this study, a newly isolated antagonistic bacterium against B. cinerea was obtained from cherry fruit and identified as Pantoea ananatis CE26. As CE26 mainly exerted its antagonistic activity through volatile metabolites, its volatile organic compound profile was analyzed by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry, leading to the identification of butyric acid (BA) as the key volatile antifungal compound. BA exhibited strong antifungal activity in vitro , completely inhibiting the mycelial growth of B. cinerea at 6 μL L −1 and significantly impairing conidial germination, while reducing gray mold severity on harvested cherry and apple fruits. Dual-fluorescence staining and cytoplasmic leakage assays revealed that BA impaired cell viability and membrane integrity, ultimately causing leakage of cellular constituents. Moreover, BA disturbed the expression of NADPH oxidase complex-associated genes and stimulated intracellular reactive oxygen species accumulation, while weakened antioxidant defenses further contributed to oxidative stress in B. cinerea . These results suggest that BA produced by CE26 inhibits B. cinerea by inducing cell membrane disruption and oxidative stress, providing a promising strategy for managing postharvest gray mold.