Effects of melatonin on the components, quality and antioxidant activities of blueberry fruits

Abstract The effect of melatonin on the components, quality and antioxidant activity in blueberry fruit after harvest were evaluated. ‘Powderblue’ blueberry fruit were treated with sterile water (control) and 0.01, 0.05, 0.25 mmol L−1 melatonin. The results showed that melatonin could effectively delay decrease of fruit firmness and increase of decay incidence and weight loss rate, among which 0.05 mmol L−1 melatonin treatment showed the best blueberry quality. Melatonin treatment could maintain the contents of ascorbic acid, anthocyanin and total phenol, reduce the accumulation of reactive oxygen species and membrane lipid peroxidation. In addition, melatonin treatment also significantly promoted the activities of antioxidant enzymes such as ascorbate peroxidase (APX), glutathione S- transferase (GST) and phenylalanine ammonia-lyase (PAL) in blueberry. Among them, 0.05 mmol L-1 melatonin treatment up-regulated the expression of antioxidant genes VcAPX, VcGST and VcPAL. These findings suggested that the melatonin can improve the antioxidant activity to a certain extent and delay the senescence process of the blueberry fruit.