High oxygen atmospheric packaging treatment regulates the postharvest changes of Chinese kale (Brassica oleracea var. alboglabra) during storage

The combination of high oxygen and nanocomposite packaging alleviated quality deterioration by promoting antioxidant capacity and phenylpropane metabolism in Volvariella volvacea

Volvariella volvacea is a highly perishable mushroom that severely affects its postharvest commercial value. This study aimed to investigate the impact of high oxygen (O2) levels combined with nanocomposite packaging on the shelf-life quality of V. volvacea. Results showed that treatment with high concentrations of O2 (80% and 100% O2) and nanocomposite packaging effectively delayed the quality deterioration of V. volvacea, resulting in better postharvest appearance, higher firmness, lower weight loss, malondialdehyde (MDA) content, and leakage of membrane electrolytes. Further analysis revealed the combination treatments ameliorated oxidative stress by inducing antioxidant enzymes and the glutathione-ascorbate (GSH-AsA) cycle at both enzymatic and transcriptional levels, thereby activating the antioxidant system. Additionally, the treatments enhanced activities of key enzymes in phenylpropane metabolism, leading to a reduction in the decrease of total phenolics and flavonoids. This work provides new insights into the development of postharvest technologies to prolong the storage life of V. volvacea.

Transcriptome Analysis Reveals the Mechanism by Which Exogenous Melatonin Treatment Delays Leaf Senescence of Postharvest Chinese Kale (Brassica oleracea var. alboglabra)

Melatonin, a pleiotropic small molecule, is employed in horticultural crops to delay senescence and preserve postharvest quality. In this study, 100 µM melatonin treatment delayed a decline in the color difference index h* and a*, maintaining the content of chlorophyll and carotenoids, thereby delaying the yellowing and senescence of Chinese kale. Transcriptome analysis unequivocally validates melatonin's efficacy in delaying leaf senescence in postharvest Chinese kale stored at 20 °C. Following a three-day storage period, the melatonin treatment group exhibited 1637 differentially expressed genes (DEGs) compared to the control group. DEG analysis elucidated that melatonin-induced antisenescence primarily governs phenylpropanoid biosynthesis, lipid metabolism, plant signal transduction, and calcium signal transduction. Melatonin treatment up-regulated core enzyme genes associated with general phenylpropanoid biosynthesis, flavonoid biosynthesis, and the α-linolenic acid biosynthesis pathway. It influenced the redirection of lignin metabolic flux, suppressed jasmonic acid and abscisic acid signal transduction, and concurrently stimulated auxin signal transduction. Additionally, melatonin treatment down-regulated RBOH expression and up-regulated genes encoding CaM, thereby influencing calcium signal transduction. This study underscores melatonin as a promising approach for delaying leaf senescence and provides insights into the mechanism of melatonin-mediated antisenescence in postharvest Chinese kale.