Enhancing Postharvest Quality of Fresh-Cut Changgen Mushrooms by Exogenous L-Cysteine Treatment: Aspects of Accumulating Amino Acids, Triggering Energy Metabolism and Enhancing Endogenous H2S Regulation.

As a rare and functional edible mushroom, the market potential of ready-to-eat fresh-cut Changgen mushrooms (Oudemansiella raphanipes) is booming in developing countries. However, fresh-cut mushrooms preservation is challenging in distribution and consumption. The present study discovered that exogenous L-cysteine (L-Cys) treatment delayed the weight loss, browning degree, nutrition depletion and microbial contamination of fresh-cut Changgen mushrooms at 4 °C. Based on transcriptomic data, exogenous L-Cys significantly activated the metabolism of 17 amino acids, including L-Cys and methionine, a prerequisite for hydrogen sulfide (H2S) synthesis. Exogenous L-Cys also stimulated the activities and gene expressions of cystathionine beta-synthase and cystathionine gamma-lyase, thereby increasing H2S levels. Furthermore, exogenous L-Cys enhanced the energy metabolism by improving cytochrome c oxidase, H+-ATPase and Ca2+-ATPase enzymes activity. Exogenous L-Cys treatment reduced the reactive oxygen species by regulating enzyme activities such as polyphenol oxidase, catalase and superoxide dismutase. This study contributes valuable insights into the physiological function of L-Cys and the role of H2S on the fresh-cut Changgen mushroom.