Antifungal activity and mechanism of an alkaloid derived from the marine fungus Aspergillus terreus BYS8 against Botrytis cinerea

BACKGROUND Botrytis cinerea , commonly known as gray mold, is one of the most significant necrotrophic plant pathogens, causing considerable economic losses in the agricultural industry. An alkaloid, methyl‐3,4,5‐trimethoxy‐2‐(2‐(nicotinamido) benzamido)benzoate (MTC), was isolated from the marine‐derived fungus Aspergillus terreus BYS8, and its antifungal activity against Botrytis cinerea is reported for the first time. RESULTS MTC displayed potent antifungal activity against Botrytis cinerea , with an EC 50 value of 10.33 μg mL −1 . It effectively inhibited the mycelial growth and spore germination of B. cinerea and demonstrated broad‐spectrum protective effects on the fruits of grape, strawberry, and cherry tomato. Additionally, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed that MTC induced severe morphological deformation in B. cinerea filaments. Furthermore, MTC increased the MDA content in B . cinerea mycelium, while the activity of antioxidant enzymes (SOD, POD, CAT, and GSH‐PX), and the soluble protein content decreased. The transcriptome analysis revealed that MTC regulated the expression of genes related to starch and sucrose metabolism, pyruvate metabolism, and the citrate cycle, which resulted in a decrease in sucrose and amylose production, pyruvate content, citrate cycle‐related enzyme activity, ATP levels, and affecting the energy metabolism imbalance and cellular dysfunction of B. cinerea . CONCLUSION These findings suggest that MTC is a promising candidate as a novel agricultural fungicide, demonstrating effective control over B. cinerea and providing a solid scientific foundation for its potential development as an alternative to conventional chemical fungicides.