Abstract: In order to explore the effect of phlorizin, a phenolic compound uniquely found in apples, on gray mold, the antifungal effect was determined by inoculation of Botrytis cinerea in vitro. The best concentration of phlorizin for in vivo test was screened and used to soak ‘Pink Lady’ apples for 20 min, followed by induction for 12 h, and then B. cinerea was inoculated. The incidence of resistance was measured and resistance-related indexes were determined regularly. Distilled water treatment was used as the control group. The results showed that phloridzin could directly inhibit the growth of B. cinerea in vitro. Phlorizin at 1.0 g/L could significantly reduce the incidence of postharvest gray mold and inhibit the expansion of lesion diameter (P < 0.05). It could also increase the activity of phenylalanine ammonialyase, peroxidase and polyphenol oxidase, and promote the accumulation of total phenols, total flavonoids and lignin. At the same time, it could reduce the content of hydrogen peroxide and increase fruit resistance. These results can provide the theoretical basis for the study on the mechanisms of postharvest diseases in apples.

Key words: phlorizin, apple, gray mold, induced resistance