Antifungal mechanisms of volatile organic compounds from Streptomyces albidoflavus SC-3 against postharvest kiwifruit rot caused by Botryosphaeria dothidea

Botryosphaeria dothidea is one of the primary pathogens responsible for kiwifruit soft rot, leading to significant postharvest economic losses. Streptomyces spp., known for producing abundant volatile organic compounds (VOCs), have emerged as a crucial biological resource for controlling postharvest diseases. This study employed wheat grain cultures of Streptomyces albidoflavus SC-3 to produce VOCs, with the aim of systematically evaluating their antifungal mechanisms against B. dothidea . The VOCs emitted by SC-3 showed remarkable antifungal activity against B. dothidea , effectively inhibiting mycelial growth and suppressing sclerotia germination. Through optimization of culture conditions including inoculation volume, culture temperature, incubation time, and dosage of wheat grains, the antifungal efficacy of VOCs produced by SC-3 was significantly improved. Strain SC-3 VOCs reduced the pathogenicity of B. dothidea in kiwifruit, thereby delaying the progression of fruit soft rot. The VOCs induced abnormal hyphal morphology and compromised cell wall and membrane integrity of B. dothidea . Transcriptomic analysis further revealed that these VOCs primarily function by disrupting energy metabolism, impairing cell membrane integrity, and disturbing redox homeostasis-related metabolic pathways. GC-MS analysis identified three antifungal VOCs, including carvone, 3,5-di-tert-butylphenol, and 3-butylidenephthalide. Carvone exhibited the strongest inhibitory effect with EC 50 value of 0.03 μL mL −1 , suggesting that it serves as the key active compound against B. dothidea . In conclusion, Streptomyces albidoflavus SC-3 VOCs, primarily carvone, effectively control kiwifruit soft rot by inhibiting the pathogen B. dothidea through multiple mechanisms.