Antimicrobial activity and mechanism of the plant-derived compound evodiamine against Phytophthora capsici.

BACKGROUND Phytophthora capsici is a devastating oomycete pathogen with major economic concern. However, the use of traditional chemical fungicides is associated with environmental pollution, and fungicide resistance is increasingly prevalent. Consequently, developing safe, effective, and environmentally friendly alternatives is critically required. Evodiamine (EVO), a bioactive alkaloid from plants, has been extensively investigated for its anti-cancer properties. However, its inhibitory effects against phytopathogens have not yet been fully elucidated. This study evaluated EVO's antimicrobial activity toward P. capsici and its potential mode of action. RESULTS EVO significantly inhibited P. capsici mycelial growth and spore germination, with median effective concentration (EC50) values of 6.48 μg mL-1 and 7.13 μg mL-1 respectively, across 108 P. capsici isolates. EVO exerted its antimicrobial effects by disrupting the cellular integrity of P. capsici, specifically targeting both the cell membrane and wall. Furthermore, EVO exhibited strong protective and curative efficacies in pepper leaves and seedlings. Genome-wide transcriptional analysis revealed that EVO treatment significantly altered the gene expression profile of P. capsici, especially affecting genes relevant to cell membrane integrity and transporter activity. CONCLUSION Overall, this study revealed that EVO showed great control efficacy against P. capsici and held promise as a novel botanical fungicide. © 2025 Society of Chemical Industry.