Effect of Combined Treatment with Phenylalanine and 1-Methylcyclopropene on Anthocyanin Biosynthesis in Peach Peel

In order to explore the effect of postharvest treatment with combined phenylalanine (Phe) and 1-methylcyclopropene (1-MCP) on the appearance quality of peach fruits, bagged peach fruits were treated after harvest with water (control), Phe, 1-MCP or Phe combined with 1-MCP (Phe + 1-MCP). The changes in peach fruit phenotype, peel color difference, anthocyanin content, and the expression of genes associated with anthocyanidin and ethylene metabolism were measured during storage. The results showed that the single treatments with Phe or 1-MCP led to a higher peel anthocyanin content compared with the control group. Furthermore, the combined treatment was more effective in increasing the synthesis of anthocyanin than the single treatments. On the 6th day of storage, the anthocyanin content in the peel in the combined treatment group was 76.71 mg/kg, which was 7.29, 3.36, and 1.33 times higher than that in the control, Phe and 1-MCP groups, respectively. Phe + 1-MCP treatment effectively enhanced the expression of genes related to the synthesis of anthocyanins (PAL, CHS, CHI, F3H, DFR, ANS, UFGT, MYB10.1, bHLH-3 and WD40-1) and reduced the expression of genes related to ethylene synthesis and signal transduction (ACS, EIN4 and EIL) in peach peel. This study not only further confirmed that 1-MCP treatment can effectively promote the synthesis of anthocyanin in peach peel, but also found a synergistic effect between Phe and 1-MCP, which will provide a theoretical basis for the application of Phe + 1-MCP in the regulation of peach color after harvest.