1-Octen-3-ol suppresses Penicillium expansum development, patulin biosynthesis and pathogenicity via oxidative stress and G-protein signaling.

Penicillium expansum is widely recognized as an important cause of postharvest apple decay, owing to its ability to induce blue mold and to produce the mycotoxin patulin, leading to significant economic losses and food safety risks. 1-Octen-3-ol, a natural volatile organic substance, has diverse biological activity. This study investigated the effects of 1-octen-3-ol on the growth, pathogenicity, and patulin biosynthesis of P. expansum, and explored the underlying antifungal mechanisms. Our results demonstrated that 1-octen-3-ol markedly restrained mycelial growth, spore germination, and sporulation, and induced microstructural damage to hyphae and spores. Moreover, 1-octen-3-ol inhibited blue mold development in apple fruit, resulting in an approximately 32% reduction in lesion development and 85% reduction in patulin accumulation in apple fruits. This reduction in patulin was accompanied by a 10%-57% decrease in the expression of patulin biosynthetic genes. Furthermore, 1-octen-3-ol treatment induced excessive reactive oxygen species accumulation, disrupted mitochondrial membrane potential, and promoted apoptosis-like cell death in fungal spores, indicating that the fungus was under severe oxidative stress. Concurrently, the genes expression involved in G-protein signaling network was decreased by 13%-83% following 1-octen-3-ol treatment. These findings reveal that 1-octen-3-ol exerts its inhibitory action by disrupting cellular redox homeostasis and interfering with G-protein signal transduction, thereby inhibited both fungal pathogenicity and secondary metabolite production. Therefore, 1-octen-3-ol presents a promising natural alternative for the management of postharvest blue mold and the mitigation of patulin contamination in apple fruit.