Transcriptomics and Proteomics Analysis Provide Insight into Metabolisms of Sugars, Organic Acids and Phenols in Hot Air Treated Peaches during Cold Storage

Peach fruit is sensitive to chilling injury during low temperature storage. In order to comprehensively study the regulatory effects of hot air (HA) treatment on the metabolic pathways in peach fruit during cold storage, the fruit subjected to HA treatment at 40 ℃ for 4 h, and then stored at (1 ± 1) ℃ for 35 days. Samples were taken after every seven days for the determination of soluble sugar, citric acid, malic acid, total phenols, total flavonoids and anthocyanins in peach fruit. Besides, peaches were selected for the analysis of transcriptomics and proteomics. Results showed that HA significantly inhibited the decreases in sucrose, citric acid, malic acid, total phenols and total flavonoids, and the increases in fructose and glucose. Furthermore, HA significantly promoted the synthesis of anthocyanins (P < 0.05). Transcriptomics and proteomics analysis showed that most deferentially expressed genes (DEGs) and proteins (DEPs) regulated by HA were mainly concentrated in carbohydrate metabolism and secondary metabolite metabolism. The metabolic changes of soluble sugars and organic acids were mainly related to the expression of invertase, sucrose synthase, sucrose phosphate synthase, malate dehydrogenase and citrate synthase. In addition, HA treatment promoted the production of phenols, flavonoids and anthocyanins by up-regulating the expression of phenylalanine ammonia lyase, 4-coumaric acid CoA ligase, chalcone synthase, dihydroflavonol 4-reductase, anthocyanin synthase and UDP flavonoid glucosyltransferase. In summary, HA treatment could effectively suppress the decreases in sugars, organic acids and phenolic substances, and promotes an increase in anthocyanins in peach fruit during cold storage.