Weifang Zuo , Le Lu , Mengyu Su , Jing Zhang , Yuying Li , Siliang Huang , Cuixia Li ,  Nan Wang ,Zongying Zhang*, Xuesen Chen.  Analysis of differentially expressed genes and differentially abundant  metabolites associated with the browning of Meihong red-fleshed  apple fruit.  Postharvest Biology and Technology 174 (2021) 111437.

Abstract: Enzymatic browning affects the quality of fresh-cut produce. To elucidate the mechanism regulating the browning of red-fleshed apple, we analyzed the transcriptome and metabolome of freshly cut Meihong apple  samples collected at 0, 0.5, and 4 h after cutting. The main differentially abundant metabolites during the  browning process were phenols, amino acids and fatty acids. Phenols are substrates for enzymatic browning and  most of them are negatively correlated with browning. Amino acids and their derivatives are associated with  non-enzymatic browning and most of them are positively correlated with browning. A transmission electron  microscopy analysis revealed the degradation of the cell membrane of cut fruit samples, which significantly  affected the fatty acid content. The differentially expressed genes were mainly related to plant–pathogen in teractions. Polyphenol oxidase (PPO) plays a major role during the early browning stage, but PPO gene  expression was not higher than WRKY, AP2 and MYB transcription factor.