Gypenoside GP5 effectively controls Colletotrichum gloeosporioides, an anthracnose fungus, by activating autophagy

Anthracnose is a plant disease caused by Colletotrichum spp., known for its widespread infectivity and extreme destructiveness. Colletotrichum gloeosporioides is a representative pathogen of anthracnose in China. Gypenosides GP4-GP7, derived from Gynostemma pentaphyllum (Thunb.) Makino, could significantly inhibit the growth of C. gloeosporioides mycelial, with EC₅₀ values of 96.98, 27.5, 38.48, and 61.59 mg L⁻¹. The inhibitory effect of these compounds surpassed the commonly used chemical pesticide chlorothalonant and plant-derived pesticide matrine. Among them, the most active compound GP5 also showed a significant inhibitory effect on spore germination and bud tube elongation of C. gloeosporioides. In addition, GP5 could effectively suppress the spread of anthracnose spots in postharvest fruit. Transmission electron microscopy and fluorescence microscopy demonstrated that GP5 primarily exerted its antifungal function by activating cellular autophagy. Additionally, proteomics analysis revealed that GP5 had an antifungal effect against C. gloeosporioides by enhancing cellular autophagy through upregulation of the expression of the autophagy-related protein Atg8. This study presents a novel approach for the control and management of anthracnose in C. gloeosporioides. Consequently, GP5 has the potential to be developed as a plant-derived fungicide for the biological control of anthracnose.