Mechanism Analysis of Amphotericin B Controlling Postharvest Gray Mold in Table Grapes

Gray mold, caused by Botrytis cinerea, is the primary factor contributing to postharvest losses in table grape fruit. In this study, we have identified amphotericin B (AMB), a natural compound originating from Streptomyces nodosus, as a promising agent in managing postharvest gray mold in table grapes. In vitro experiments demonstrated that 0.2 mg/L AMB achieved an inhibition rate of over 90% against B. cinerea in PDA medium, and in vivo assays on grape berries showed that 200 mg/L AMB treatment could completely suppress the occurrence of gray mold disease. A mechanism analysis found that AMB treatment disrupted the plasma membrane structure, which consequently triggered cellular leakage and induced cell death. Furthermore, AMB application effectively modulated the transcriptional profile of genes related to redox homeostasis, transmembrane transport, and peroxidase functions in B. cinerea, thereby reducing the virulence of the fungus. In addition, AMB treatment had the potential to activate defense mechanisms in table grapes by enhancing the activities of ROS-scavenging enzymes and defense-associated enzymes. Collectively, AMB can be regarded as a natural antifungal agent that effectively combats B. cinerea, thereby extending the postharvest shelf life of table grape fruit.