Ginsenoside Rk1 inhibits postharvest fruit anthracnose by disrupting reactive oxygen species (ROS) homeostasis and activating the autophagic mechanism in Colletotrichum gloeosporioides

Anthracnose is a highly contagious and destructive plant disease caused by Colletotrichum gloeosporioides . The objective of this study was to investigate the antifungal activity and mechanism of ginsenoside Rk1 ( GRk1 ) against C. gloeosporioides. In vitro experiments demonstrated that GRk1 exhibited substantial antifungal activity, with EC 50 values of 64.58 mg L −1 , surpassing the plant-derived pesticide d -limonene . Additionally, GRk1 could effectively suppress the dissemination of anthracnose spots in postharvest fruit. By observing the microstructure of C. gloeosporioides , it was observed that the mycelium structure underwent notable changes, and autophagosomes engulfed the organelles in the experimental groups. Fluorescent staining revealed specific signals in mycelial autophagosomes, and Western Blot analysis confirmed the upregulation of the autophagy-related protein Atg8. These findings indicate that GRk1 may activate the autophagy process by promoting Atg8 expression. Proteomic analysis revealed that the expression of Sec20 and Mpv17 proteins was significantly downregulated, whose dysregulated expression is associated with the crosstalk between SNAREs and peroxisomes during vesicle trafficking and metabolic processes. Assessment of catalase (CAT) activity, hydrogen peroxide (H₂O₂) content, and superoxide anion (O₂ − ) levels further demonstrated that GRk1 could disrupt intracellular reactive oxygen species (ROS) homeostasis in mycelia. Moreover, the introduction of the ROS scavenger N -acetylcysteine (NAC) markedly inhibited autophagy, indicating that GRk1 promotes autophagy by inducing oxidative stress. Collectively, GRk1 inhibits pathogens via the ROS-autophagy axis. These findings suggested that GRk1 holds potential as a promising alternative to fungicides for the biological control of anthracnose.