Melatonin treatment induces DNA methylation to alleviate chilling induced-browning in cold stored peach fruit

Chilling injury (CI) often occurs in postharvest peach fruit during low-temperature storage, and exogenous melatonin (MT) treatment has been demonstrated to alleviate CI in cold-stored peach fruit. In this study, we further investigated the effect of MT treatment on DNA methylation in relation to the chilling-induced browning in cold stored peaches. The results revealed that MT treatment upregulated PpPAL expression while simulta-neously suppressing the transcripts of PpPPO and PpPOD. This dual effect resulted in the increased accumulation of phenolics, effectively reducing the incidence of browning in peaches stored at 4 degrees C. In addition, MT treatment increased the activities of methylesterase and demethylase, affecting significant changes in the DNA methylation levels of the local genes PpPPO, PpPOD and PpPAL, which suggested that MT treatment could mediate DNA methylation of the browning-related genes such as PpPPO, PpPOD and PpPAL, and consequently increased the phenolic contents and alleviated browning symptoms in cold-stored peaches.