Effects of 1-methylcyclopropene Treatment on the Quality of Red ‘Fuji’ Apples Fruit during Short-time Storage

The aim of this study is to determine the mechanism through which 1-methylcyclopropene (1-MCP) affects the quality of red ‘Fuji’ apples, which were stored for a short-term duration of time. Red ‘Fuji’ apples were treated with 1-MCP (1.0 μl/L), stored at 25 ℃ for 0 h, 12 h, 24 h, 48 h, 72 h, 96 h, and ethylene production was measured. An integrated metabolomic and transcriptomic analysis was performed on apples stored for 24 h. The release of ethylene was significantly delayed from red “Fuji” apples, which were subjected to 1-MCP treatment. By performing an integrated method of transcriptome and metabolome analyses, we identified 117 differentially expressed genes (DEGs) and 44 differentially accumulated metabolites (DAMs). By performing functional enrichment analysis, we found that DEGs were involved in the following pathways: carbon metabolism (LPD2, gpmA, LTA2, ACC, PSAT1, MdCAS2), phytohormone signal transduction (EBF1), amino acid metabolism (MdACS-1), fatty acid metabolism (LOX1.5, KCS4, KAS1), energy metabolism (Lhcb1, Lhcb6, PsbY, GPDHC1, PUMP5), metabolic pathways (TRE1, HEXO1) and cell wall metabolism (CSLG2). Thus, these DEGs were involved in the ripening of fruits, and they controlled the quality of fruits at the post-harvest stage. The metabolites were enriched with DAMs. These were found to be individually involved in the metabolic pathway, secondary metabolite biosynthesis, phenylpropanoid biosynthesis, flavonoids, and flavonol synthesis. The results indicate that 1-MCP inhibits the biosynthesis of ethylene and suppresses energy metabolism. Moreover, it also down-regulates metabolic pathways and the enzymatic genes related to fruit quality. Therefore, 1-MCP delays the ripening of fruits at the post-harvest stage. The study helps us understand how 1-MCP treatment affects the ripening and quality of fruits.