Leaf senescence is a major concern for postharvest leafy vegetables, as leaves are highly prone to yellowing and nutrient loss, resulting in reduced commercial value and limited shelf-life. This study aimed to investigate the effect of L-cysteine (L-cys) on postharvest Chinese flowering cabbage stored at 20 °C. The results showed that 0.5 g L⁻¹ L-cys treatment effectively slowed leaf senescence by downregulating chlorophyll degradation genes (BrNYC1, BrNOL, BrPPH, BrPAO, BrNYE, and BrSAGs) and senescence marker gene BrSAG12. Moreover, this treatment exhibited positive influence on the nutritional quality of cabbage. Also, L-cys treatment maintained ROS homeostasis, preventing excessive ROS accumulation and lipid membrane oxidation. L-cys treatment also maintained a higher total antioxidant capacity and scavenging rate of •OH and O₂^•−. Additionally, L-cys treatment maintained high levels of ascorbate and glutathione and activated antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the expression of the encoding genes. Furthermore, L-cys treatment elevated endogenous H₂S levels, which are correlated with increased L-cysteine desulfhydrase activity and the upregulation of H₂S biosynthesis-related genes. These findings suggest that L-cys can delay leaf senescence by reducing chlorophyll breakdown, maintaining ROS homeostasis, and stimulating endogenous H₂S production.

Postharvest loss of fruits and vegetables remains a significant global challenge, while concerns over chemical residues, energy consumption, and storage-induced physiological disorders have accelerated the search for safe and eco-friendly preservation strategies. As key plant metabolites and signaling molecules, amino acids are gaining more attention for their roles in postharvest biology. This article reviews the primary postharvest issues of fruits and vegetables, the functional roles of representative amino acids, including γ-aminobutyric acid (GABA), glutamate (Glu), arginine (Arg), cysteine (Cys), proline (Pro), and phenylalanine (Phe), with emphasis on the postharvest applications and mechanisms of action of amino acids. Increasing evidence suggests that amino acids can improve postharvest performance mainly by mitigating oxidative stress, enhancing ROS scavenging capacity, retaining cellular membrane integrity, regulating osmotic and energy metabolism, activating phenylpropanoid-mediated defense, and modulating respiration–ethylene processes. These responses contribute to reducing chilling injury, decay, browning, softening, and senescence, thereby helping maintain color, texture, nutritional value, and storage quality. However, the effectiveness of amino acid treatments varies depending on the product types and conditions, and is influenced by concentration, application method, storage environment, and combined preservation strategies. The information in this review provides a systematic foundation for understanding amino acid-mediated modulation mechanisms of postharvest horticultural crops and for developing more environmentally friendly postharvest preservation technologies, while highlighting the need for treatment standardization, mechanistic validation, and commercial-scale evaluation.

Alternaria sp. is a major pathogen causing postharvest storage decay of European plum. This study evaluated the antifungal activity of low-temperature plasma (LTP) against Alternaria sp. and elucidated its mechanism. With increasing LTP exposure, both mycelial growth and spore germination of Alternaria sp. were progressively inhibited; at 70 kV for 40 s, inhibition reached 100% and 99.32 ± 0.59%, respectively. Ultrastructural observations revealed abnormal spore morphology (swelling and shrinkage). Fluorescence microscopy showed compromised membrane integrity and increased permeability. The activities of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) decreased by 86.08%, 82.86% and 75.47%, respectively, compared with the 0 s control group. Therefore, the accumulation of H₂O₂ and O₂⁻ in cells destroys the redox homeostasis, further damages the membrane structure and function, and leads to the time-dependent increase in nucleic acid leakage, soluble protein leakage and malondialdehyde (MDA) accumulation. Collectively, LTP exhibits strong antifungal activity against Alternaria sp. and shows promise for controlling postharvest diseases of plum fruit.