Hardy kiwifruit Jiaosu controls postharvest gray mold of strawberry via dual mechanisms: Direct antifungal activity and induced host resistance

Strawberry gray mold, triggered by Botrytis cinerea , ranks among the main postharvest diseases of this fruit. Plant Jiaosu (hereafter referred to as GE), also known as “garbage enzyme,” is a natural fermented product containing multiple bioactive components and has potential value in disease control. Previous studies have confirmed its inhibitory effect against B. cinerea , yet the underlying mechanism remains unknown. In this study, hardy kiwifruit Jiaosu was used to evaluate its efficacy in controlling postharvest gray mold of strawberry. In vitro experiments showed that GE strongly suppressed both mycelial growth and spore germination of B. cinerea , and induced intracellular leakage by disrupting cell membrane integrity. In vivo inoculation assays revealed that at the end of storage, the disease incidence of GE‑treated strawberries was 31.7%, with a lesion diameter of only 5.1 mm, significantly lower than that of the control group. Meanwhile, GE treatment increased the activities of polyphenol oxidase (PPO), peroxidase (POD), and catalase (CAT), and promoted the accumulation of total phenolics and flavonoids. These results indicate that GE controls postharvest gray mold of strawberry through a dual mechanism, direct inhibition of the pathogen and enhancement of host resistance, making it a potential candidate for a novel green preservative.