Effects of exogenous melatonin on ripening and decay incidence in plums (Prunus salicina L. cv. Taoxingli) during storage at room temperature

The effects of exogenous melatonin on ripening and decay incidence of plum fruit (Prunus salicina L. cv. Taoxingli) were investigated after the plums at green mature stage were dipped in 0 (as the control), 0.05, or 0.1 mmol center dot L-1 melatonin solution for 1 h, and then stored at room temperature (25 +/- 1 degrees C) and 75-80% relative humidity (RH) for 14 d. The results showed that melatonin treatments could slow the ripening process as indicated by the firmness, respiration rate, and ethylene production, and decreased the weight loss and decay incidence of plum fruit during storage. Moreover, the melatonin treatments activated the phenylpropanoid pathway by increasing the activities of phenylalanine ammonia-lyase (PAL), 4-coumarate-coenzyme A ligase (4CL), cinnamate-4-hydroxylase (4CH) and peroxidase (POD), and accompanied by higher contents of total phenols and lignin, which might be contributed to enhancing the disease resistance in plum fruit during storage. Therefore, it was suggested that melatonin application could be a promising method to suppress postharvest deterioration, maintain fruit quality and extend the shelf-life of plum fruit.