Rhodiola rosea L. Essential Oil Reduces Postharvest Strawberry Decay by Disrupting Botrytis cinerea Cell Wall and Membrane Integrity

Botrytis cinerea poses a major threat to postharvest strawberries, causing significant losses due to gray mold. As a plant-derived antifungal agent, Rhodiola rosea L. essential oil (REO) possesses considerable healthcare benefits. However, its effectiveness and underlying mechanisms in the maintenance of postharvest products remain poorly understood. This study demonstrated that REO at 0.5 µL/mL completely inhibited the growth of B. cinerea under in vitro conditions. In vivo fumigation treatment with REO alleviated the severity of gray mold in strawberry fruit. Additionally, REO decreased natural decay and positively impacted marketability, as evidenced by higher firmness, total soluble solids, and ascorbic acid contents, as well as more favorable color attributes. Further investigations involving scanning electron microscopy, calcofluor white (CFW) staining, propidium iodide (PI) staining, 2′,7′-dichlorodihydrofluorescein diacetate assay, and cellular leakage tests were conducted to investigate the effects of REO treatment on gray mold mycelium. Results showed that REO treatment induced severe morphological distortions and collapse of mycelium. Within 30 min of exposure, REO triggered a sharp increase in PI fluorescence accompanied by a decrease in CFW fluorescence, without inducing an elevation in intracellular reactive oxygen species levels. The elevated leakage of nucleic acids and soluble proteins further confirmed that REO compromised the integrity of the cell barrier in B. cinerea. Collectively, these findings indicate that REO exerts potent antifungal activity by disrupting the integrity and functionality of B. cinerea cellular barriers, thereby reducing postharvest decay and positively impacting the marketability of strawberry fruit. Taken together, our findings suggest that REO represents a promising natural alternative for environmentally sustainable postharvest protection of strawberries.