This study employed integrated multi-omics approaches to elucidate, from the perspective of amino acid metabolism, the adaptive mechanism of Penicillium digitatum under modified atmosphere packaging (MAP) conditions. Comparative analysis of natural air (Air), controlled atmosphere (CA), and MAP treatments revealed that MAP upregulated the expression of the hercynylcysteine S-oxide synthase (HCSOS), aldehyde dehydrogenase (ALDH), and monoamine oxidase (MAO) genes, thereby enhancing histidine-derived ergothioneine and methionine levels, and subsequently boosting glutathione-mediated redox homeostasis. Meanwhile, MAP induced the expression of the dihydroxyacid dehydratase (DHAD), saccharopine dehydrogenase (SDH), and arginosuccinate lyase (ASL) genes, redirecting valine, lysine, and arginine into the tricarboxylic acid (TCA) cycle to fuel ATP production. MAP also enhanced ASL-mediated arginine degradation and urea cycle activity, reducing arginine accumulation when compared to CA treatment. In contrast, while MAP induced upregulated expression of the pyrroline-5-carboxylate dehydrogenase (P5CDH) and D-amino acid oxidase (DAAO) genes, CA treatment promoted proline accumulation, reflecting stress-specific metabolic flexibility. Collectively, these findings demonstrate that MAP triggers transcriptional reprogramming of amino acid metabolism to coordinate oxidative defense, energy generation, and osmotic balance. By modulating these metabolic pathways and regulatory genes under MAP conditions, fungal adaptability can be disrupted. Hence, this study provides a promising strategy for suppressing green mold development, extending the postharvest shelf life, and improving the quality of fruits and vegetables.

To investigate the effects and molecular basis of leucine on carbohydrate and energy homeostasis in postharvest broccoli, an integrated transcriptomic and metabolomic analysis was conducted on postharvest broccoli treated with leucine soaking. Results showed that leucine treatment elevated the ATP and ADP contents and energy charge, which consequently enhanced the cellular energy status of postharvest broccoli. Leucine treatment suppressed alcoholic fermentation by down-regulating pyruvate decarboxylase and alcohol dehydrogenase expression. It enhanced the tricarboxylic acid (TCA) cycle by up-regulating the expression of pyruvate dehydrogenase E1 and E2 subunits, citrate synthase, and malate dehydrogenase and promoting glycolysis and the conversion of glucose into pyruvate, thereby directing a greater flux of pyruvate into the TCA cycle. Leucine treatment improved oxidative phosphorylation, effectively converting the energy stored in reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) into ATP. The findings offer a theoretical basis for developing strategies to improve energy status and thereby extending the commercial shelf life of postharvest broccoli.

In order to explore the molecular mechanism of the response of the antioxidant system in broccoli heads to high O₂ stress, the changes in the antioxidant system and related protein expression in broccoli heads under different O₂ concentrations (5% O₂ + 5% CO₂, 20% O₂ + 5% CO₂ and 40% O₂ + 5% CO₂) were investigated by physiological and biochemical analysis and isobaric tags for relative and absolute quantitation (iTRAQ) proteomics. The gene ontology (GO) annotation, the clusters of orthologous groups of proteins (COG) analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that a total of 76 differentially expressed proteins related to the antioxidant system were identified in this study, which were involved in the ascorbate-glutathione cycle, glucosinolate degradation, and the metabolism of polyphenols, flavonoids and antioxidant enzymes. The proteomic analysis showed that the 40% O₂ + 5% CO₂ treatment significantly inhibited the activity of an ascorbate peroxidase and three glutathione peroxidases, thereby inhibiting the ascorbate-glutathione cycle in broccoli compared with the 5% O₂ + 5% CO₂ treatment. Meanwhile, the 40% O₂ + 5% CO₂ treatment significantly increased the activities of 16 myrosinases and promoted the degradation of glucosinolate. In addition, the expression of shikimate dehydrogenase in the 40% O₂ + 5% CO₂ treatment group decreased by 23% compared with that in the 5% O₂ + 5% CO₂ treatment group, inhibiting shikimic acid synthesis and the accumulation of polyphenols and flavonoids. This study has revealed the cause of rapid yellowing and senescence in broccoli heads under high O₂ stress, which provides a theoretical basis for the development of new broccoli preservation technology and the remission of high O₂ stress.

To determine the effects of preharvest arginine spraying on the nutritional level of broccoli and the mechanism of action of arginine in improving the storage quality of broccoli, arginine spraying (5 mmol/L) was conducted at 0, 1, 3, and 5 days before harvest. The appearance, respiration rate, mass-loss rate, electrolyte leakage, glucosinolate, ascorbic acid, total phenol, total flavonoid, total sugar and sucrose contents, and sucrose phosphate synthase (SPS), invertase (INV), sucrose synthase synthesis (SSS) and cleavage (SSC) activities of broccoli samples were observed after 0, 2, 4, 6, 8, and 10 days of storage. The results showed that spraying arginine at 5 days preharvest (5-ARG) helped to inhibit broccoli respiration during storage, delay electrolyte leakage, and maintain broccoli color. Furthermore, during the growth stage, total sugar accumulation was higher in the 5-ARG group. In addition, during the storage period, sucrose synthesis was accelerated, while sucrose cleavage was inhibited, resulting in more sucrose retention in postharvest broccoli. In conclusion, 5-ARG resulted in the accumulation of more nutrients during the growth process and effectively delayed the quality decline during storage, thereby prolonging the shelf life of broccoli. Therefore, this study provides a theoretical basis for improving postharvest storage characteristics of broccoli through preharvest treatments.