6’-O-Caffeoylarbutin Treatment Improves the Resistance to Gray Mold of Postharvest Blueberry Fruit by Activating Phenanthrene Metabolism

To study the effect of 6’-O-caffeoylarbutin (CA) treatment on the prevention and control of gray mold in postharvest blueberry fruit and its effect on fruit phenylpropane metabolism, blueberries were soaked in 2.5 mmol/L CA solution or distilled water as the control. The results showed that CA treatment significantly reduced the incidence of gray mold in postharvest blueberry fruit and inhibited the expansion of lesion diameter when compared with the control. Meanwhile, it increased the activities of phenylalanine ammoniase (PAL), cinnamic acid-4-hydroxylase (C4H), 4-coenzyme coenzyme A ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), polyphenol oxidase (PPO) and peroxidase (POD), as well as the contents of total phenols, flavonoids and lignin, with few adverse effects on the storage quality. It is concluded that CA treatment could promote the synthesis and accumulation of resistance-related substances and consequently enhance the resistance to gray mold by activating the enzyme activities related to phenylpropane metabolism in postharvest blueberry fruit.