Osthole Suppresses Penicillium Choerospondiatis Growth and Blue Mold Development in Postharvest Fruits by Inducing Autophagic Activity

Blue mold induced by Penicillium choerospondiatis is a primary cause of growth and postharvest losses in the fruit of Phyllanthus emblica. There is an urgent need to explore novel and safe fungicides to control this disease. Here, we demonstrated osthole, a natural coumarin compound isolated from Cnidium monnieri, exhibited a strong inhibitory effect on mycelia growth, conidial germination rate and germ tube length of P. choerospondiatis, and effectively suppressed the blue mold development in postharvest fruit. The median effective concentration of osthole was 9.86mg/L. Osthole treatment resulted in structural disruption of the cell wall and induced autophagic vacuoles containing cytoplasmic components in fungal cells. Transcriptome analysis revealed that osthole treatment led to the differentially expressed genes mainly enriched in the cell wall synthesis, TCA cycle, glycolysis/ gluconeogenesis, oxidative phosphorylation. Moreover, osthole treatment led to increase genes expression involved in peroxisome, autophagy and endocytosis. Particularly, the autophagy pathway related genes (PcATG1, PcATG3, PcATG15, PcATG27, PcYPT7and PcSEC18) were prominently up-regulated by osthole. Summarily, these results indicated osthole suppressed P. choerospondiatis growth by inducing autophagic activity. Osthole has potentials to develop as a natural antifungal agent for controlling blue mold disease in postharvest fruits.