Efficacy of Debaryomyce hansenii in the biocontrol for postharvest soft rot of strawberry and investigation of the physiological mechanisms involved

• D. hansenii significantly reduced the incidence of postharvest soft rot of strawberry. • D. hansenii can stably colonize the surface and wounds of strawberry. • D. hansenii reduced the spore germination rate and germ tube length of R. stolonifer . • D. hansenii induced the activities of SOD, POD, CAT, APX, PPO and PAL in strawberry. • D. hansenii increased total phenolic, flavonoid and anthocyanin content in strawberry. The postharvest disease of strawberries caused by Rhizopus stolonifer caused enormous financial losses. This study investigates the efficacy of antagonistic yeast Debaryomyce hansenii in the biocontrol of postharvest soft rot of strawberries and the physiological mechanisms involved. The results showed that D. hansenii significantly reduced the incidence of postharvest soft rot of strawberry, reduced the natural decay incidence of postharvest strawberry, and had no adverse effects on quality parameters of strawberries. In vitro experiments showed that D. hansenii reduced the spore germination rate and germ tube length of R. stolonifer . D. hansenii can also stably colonize the surface and wounds of strawberries at either 4 °C or 20 °C. Meanwhile, the activities of antioxidant-related enzymes superoxide dismutase, peroxidase, catalase, ascorbate oxidase and resistance-related enzymes polyphenol oxidase and phenylalanine ammonia-lyase were significantly higher in D. hansenii -treated strawberries than in control. Meanwhile, the contents of resistance-related substances including total phenols, flavonoids and anthocyanins were also increased in D. hansenii -treated strawberries. This study suggested that D. hansenii has the potential to control postharvest soft rot of strawberry by the mechanism involving inhibition of spore germination and germ tube length of R. stolonifer and induction of increased activities of defense-related enzymes and substances in strawberry.