D-Cysteine preserves postharvest quality of fresh-cut button mushrooms by regulating antioxidant defense system and activating H2S biosynthesis

Consumers favor fresh-cut button mushrooms, yet their shelf life is hampered by rapid quality decline. This research investigates the effects of a 0.5 g/L D -cysteine ( D -Cys) application on the quality and physiological responses of fresh-cut button mushrooms. Findings reveal that D -Cys application notably postponed the mushrooms browning, curtailed weight reduction, and decreased malondialdehyde (MDA) levels, lipoxygenase (LOX) activity, and increase the levels of reducing sugars. Concurrently, it boosted soluble protein content. Moreover, D -Cys mitigated the generation of superoxide anions (O 2 − ) and hydrogen peroxide (H 2 O 2 ) while reducing catalase (CAT) activity. It also enhanced the activities of superoxide dismutase (SOD), glutathione reductase (GR), and phenylalanine ammonia-lyase (PAL), and diminished those of polyphenol oxidase (PPO) and peroxidase (POD). Furthermore, treatment with D -Cys significantly stimulated the endogenous production of hydrogen sulfide (H 2 S) in fresh-cut button mushrooms. This effect was accompanied by an enhancement in the activity of enzymes AbCBS, AbCSE, and AbMST, which are crucial in the metabolic pathways associated with sulfur metabolism. However, the beneficial effects of D -Cys were significantly diminished when mushrooms were co-treated with 1 mmol/L propargylglycine (PAG). Additionally, transcriptome sequencing analysis revealed that the genes with differential expression in the D -Cys group were mainly associated with oxidation–reduction process, cysteine metabolic process, cysteine biosynthetic process, oxidoreductase activity, POD activity, and sulfur metabolism. Collectively, these results indicate that D -Cys maintains the quality of fresh-cut button mushroom by regulating the antioxidant enzyme activity, converting to endogenous H 2 S, and converting to L- cysteine ( L -Cys).