Role of exogenous melatonin in table grapes: first evidence on contribution to the phenolics-oriented response

Abstract Melatonin (MLT) has gained increasing attention due to its pleiotropic effects. In present study, ‘Kyoho’ grapes were immersed in 200 μM of MLT to investigate the role of exogenous melatonin in postharvest metabolism response. Results indicated that berry abscission and rotten index was reduced by 37.50% and 58.37%, respectively, by exogenous MLT treatment, while the amino acid accumulation was greatly enhanced. Furthermore, the endogenous MLT biosynthesis was activated, where the transcript expression of genes, encoding tryptophan decarboxylase, tryptophan decarboxylase, N-acetylserotonin methyltransferase and N-acetyltransferae were upregulated significantly (p