Antifungal activity and mode of action of polyphenolic-rich pomegranate peel extract against gray mold and its application on strawberry

Botrytis cinerea , a widespread pathogen, causes gray mold in many plants. This study investigated the antifungal activity and mode of action of polyphenolic-rich n-hexane fraction of pomegranate peel ethanol extract (HFPPE) against B. cinerea and evaluated its potential to enhance postharvest strawberry fruit resistance. The HFPPE inhibited B. cinerea by impairing cell membrane integrity, increasing cytoplasmic outflow and malondialdehyde levels, and reducing trehalose and ergosterol levels. Additionally, HFPPE increased apoptosis in B. cinerea spores by elevating ROS (reactive oxygen species) and inducing mitochondrial membrane dysfunction. Furthermore, transcriptomic analysis identified 1,250 upregulated and 3,503 downregulated genes in HFPPE treated mycelia. These genes were primarily involved in lipid and carbohydrate metabolism, suggesting diminished energy production and compromised antioxidant system. These transcriptomic variations were further confirmed by metabolomic analysis. Moreover, HFPPE treatment reduced strawberry fruit decay by increasing phenolic content and strengthening the cell wall, while maintaining firmness, thereby improving disease resistance. For the first time, this study provided comprehensive evidence that the synergistic action of polyphenols in HFPPE exerts multi-target antifungal effects through membrane disruption, oxidative stress, metabolic interference, and host resistance induction, highlighting its potential as a natural substitute for controlling gray mold and reducing strawberry postharvest deterioration. • HFPPE inhibited B. cinerea by disrupting membrane integrity. • HFPPE decreased ergosterol and trehalose contents in B. cinerea. • HFPPE triggered apoptosis by mitochondrial dysfunction and ROS accumulation. • HFPPE impacted fungal lipid and carbohydrate metabolism. • HFPPE treatment maintained strawberry fruit quality.