A triterpenoid compound DZL against phytopathogenic fungi via disrupting cellular structures to regulating ROS and inducing autophagy

Fungi are prevalent crop pathogens that severely threaten crop yields and quality. The long-term and extensive use of chemical fungicides has led to the emergence of fungicide-resistant pathogens and a growing risk of excessive pesticide residues. Therefore, identifying efficient and eco-friendly antifungal agents has become a key research priority. Natural compounds, including alkaloids, terpenoids, flavonoids, and peptides, are valuable sources of new antifungal agents. In this study, we used antimicrobial assays to screen and identify the plant origin triterpenoid demethylzeylasteral (DZL) as an inhibitor of multiple phytopathogenic fungi, including Colletotrichum and Fusarium. Further investigations showed that DZL disrupts fungal cell wall and membrane integrity, and suppresses the activity of antioxidant enzymes such as POD, PPO, SOD, and CAT. These effects are associated with intracellular accumulation of ROS, which may alter the gene expression profile, induce autophagy and ultimately lead to fungal programmed cell death. In summary, this study reveals the phytopathogenic fungus responses associated with the antifungal activity of DZL and provides a preliminary basis for its subsequent development and application, while its practical value remains to be validated in further studies.