Metabolomic and transcriptomic analyses reveal the regulation mechanism of postharvest light-induced phenolics accumulation in mango peel

Phenolics are important secondary metabolites and antioxidants in plants. Mango fruit accumulate abundant phenolic compounds, while the effect of light on the accumulation of different phenolic components in mango peel and the relevant molecular mechanism are still unknown. In this study, mature 'Guifei' mango fruit was subjected to postharvest UV-B/white light treatment, fruit peel was sampled for metabolomic and transcriptomic analyses. The results showed that light induced the accumulation of anthocyanins, flavonoids, and phenolics, thus increasing the antioxidant capacity in mango peel. A total of 1223 phenolic metabolites were detected in mango peel, 36 phenolic compounds were defined as key differentially accumulated metabolites (DAMs) regulated by light. Among the DAMs, the accumulation of 33 compounds was promoted by light, and 30 of these were flavonoids. Light up-regulated most phenolics biosynthesis and light signaling pathway genes and also regulated expression of plant hormone signaling pathway genes. Transcription factors (TFs) such as MYB, C2H2 and HSF were identified as candidates regulating phenolics biosynthesis in mango. Our findings not only provide information for commercial application of light in promoting mango fruit appearance and increasing phenolics content and antioxidant capacity, but also reveal important aspects of the molecular regulation of light-induced phenolics accumulation in mango peel.