Melatonin application inhibits anthocyanin biosynthesis in postharvest peach fruit as revealed by transcriptional and liquid chromatographic–tandem mass spectrometric analysis

Abstract BACKGROUND Anthocyanins are essential secondary metabolites in plants, significantly contributing to fruit coloration and offering a wide range of health benefits to consumers. This study investigated the effect of melatonin treatment on anthocyanin biosynthesis in ‘Baifeng’ peaches during storage. The peaches were treated with 100 μmol L −1 melatonin and stored at room temperature (25 ± 1°C) for 9 days. The total anthocyanin content, enzymatic activities, and gene expression levels were measured, and anthocyanin derivatives were analyzed using liquid chromatography–tandem mass spectrometry (LC‐MS/MS). RESULTS The transcription factors (TFs) bHLH63 (Prupe.8G095700), MYB44 (Prupe.1G430000), and WD40‐1 (Prupe.2G319500) were identified through transcriptome sequencing. LC‐MS/MS analysis revealed that cyanidin‐ and pelargonidin‐derived compounds play the most significant role in color formation in ‘Baifeng’ peaches. In the melatonin‐treated group, fruit firmness was significantly higher than that in the control, whereas ethylene production, anthocyanin content, anthocyanin synthase activity, and the expression levels of anthocyanin‐encoding genes and TFs were markedly lower compared to the control group. CONCLUSION The application of melatonin inhibited anthocyanin synthesis in peach fruit, as evidenced by the suppression of upstream transcriptional regulation, gene expression, and downstream metabolite accumulation. This effect may be associated with melatonin's inhibition of ethylene production. Further in‐depth studies are needed to provide more detailed validation at the molecular level. The results have elucidated the underlying mechanisms responsible for the postharvest changes in the flesh phenotype of ‘Baifeng’ peaches following melatonin treatment. © 2025 Society of Chemical Industry.