Mechanistic investigation of sucrose monostearate-mediated antifungal effects against Penicillium oxalicum.

Penicillium oxalicum is a major postharvest pathogen of kiwifruit, causing substantial economic losses. This study investigated the antifungal activity and mechanism of sucrose monostearate (SMS) against P. oxalicum. The minimum inhibitory concentration (MIC) of SMS was determined to be 1.25 g L- 1, which significantly inhibited spore germination by 88.28% and reduced mycelial growth by 65.94% (p < 0.05). Mechanistically, SMS at 1.25 g L- 1 induced intracellular ROS accumulation by 1.7-fold, suppressed catalase (CAT) and peroxidase (POD) activities by 54% and 60%, and increased malondialdehyde (MDA) content by 2.5-fold, confirming severe membrane lipid peroxidation and content leakage. Scanning electron microscopy revealed marked hyphal deformation, and in vivo assays showed that SMS reduced kiwifruit lesion diameter by 83.7% compared to controls. These findings demonstrate that SMS, as a single-ester antifungal agent, disrupts fungal membrane integrity and exhibits strong potential for postharvest disease control.