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 (<i>Oudemansiella raphanipes</i>) is booming in developing countries. However, fresh-cut mushrooms preservation is challenging in distribution and consumption. The present study discovered that exogenous <i>L</i>-cysteine (<i>L</i>-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 <i>L</i>-Cys significantly activated the metabolism of 17 amino acids, including <i>L</i>-Cys and methionine, a prerequisite for hydrogen sulfide (H₂S) synthesis. Exogenous <i>L</i>-Cys also stimulated the activities and gene expressions of cystathionine beta-synthase and cystathionine gamma-lyase, thereby increasing H₂S levels. Furthermore, exogenous <i>L</i>-Cys enhanced the energy metabolism by improving cytochrome c oxidase, H⁺-ATPase and Ca²⁺-ATPase enzymes activity. Exogenous <i>L</i>-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 <i>L</i>-Cys and the role of H₂S on the fresh-cut Changgen mushroom.