Sapindus mukorossi saponins inhibit gray mold on strawberry fruit by impairing membrane integrity and organellar homeostasis of Botrytis cinerea

Fungal diseases are major adverse factors leading to quality deterioration and spoilage of postharvest fruit. Hence, the exploration of safe and efficient measures to control fungal pathogens is crucial for the sustainable development of the fruit industry. In this study, it was found that Sapindus mukorossi saponins inhibited in vitro mycelial growth of B. cinerea and gray mold on strawberry fruit in a dose-dependent manner. This inhibitory effect was attributed to the impairment in membrane potential and integrity, induction of autophagic-like vacuoles, and disturbance in organellar homeostasis of B. cinerea, as revealed by fluorescence labeling and ultrastructural observations. Moreover, S. mukorossi saponins damaged normal structures of mitochondria and induced oxidative bursts in the cytoplasm, thereby contributing to the abolished cell vitality. These results suggest that S. mukorossi saponins may be utilized as safe fungicide alternatives to control gray mold on postharvest fruit.