Rosa roxburghii fruit were used as research objects to study the effects of different concentrations of benzothiazole (BTH) treatment on quality parameters, reactive oxygen species (ROS) metabolism, and the phenylpropanoid pathway during storage at 4°C for 14days. Results showed that BTH effectively delayed senescence with lower decay incidence, weight loss, and lipid peroxidation level and maintained the quality with higher contents of total soluble solid (TSS) content, titratable acidity (TA) in R. roxburghii fruit. Moreover, BTH increased hydrogen peroxide (H₂O₂) content, superoxide anion (O₂^•−) production rate, and the activities and expression of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione (GSH) reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and peroxidase (POD), and the contents of GSH and ascorbic acid (AsA), but reduced the oxidized GSH (GSSG) content. In addition, the activities and gene expression of phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL) and the concentrations of flavonoids, total phenols, and lignin were significantly elevated by BTH. These findings imply that BTH can delay senescence and maintain the quality of R. roxburghii fruit by modulating ROS metabolism and the phenylpropanoid pathway under low-temperature conditions.

The application of melatonin (MT) has been shown to improve the quality during the storage of fruits and vegetables. The primary objective of this study is to investigate the effects of MT on the quality of fresh-cut Gastrodia elata during low-temperature (4 °C) storage. The results indicated that MT treatment not only suppressed the respiratory rate and malondialdehyde content but also slowed down the decline in total acidity and total soluble solids, effectively inhibiting microbial growth and enhancing the product safety of fresh-cut G. elata. The treatment with MT reduced the superoxide anions and hydrogen peroxide production, as well as inhibiting the activity and expression of peroxidase and polyphenol oxidase. Additionally, it led to increased activity and the expression of antioxidant-related enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase, while also resulting in elevated levels of ascorbic acid and glutathione. Furthermore, the treatment with MT induced an increase in the total phenolic and flavonoid content of fresh-cut G. elata and enhanced the activity and expression of key enzymes involved in the phenylpropanoid pathway (phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumarate: CoA ligase). In summary, MT enhances the antioxidant capacity by activating both the ROS metabolism and phenylpropanoid pathway, thus maintaining the quality of fresh-cut G. elata.

Brunfelsia calycina flowers lose anthocyanins rapidly and are therefore well suited for the study of anthocyanin degradation mechanisms, which are unclear in planta. Here, we isolated an anthocyanin-β-glycosidase from B. calycina petals. The MS/MS (Mass Spectrometry) peptide sequencing showed that the enzyme (72 kDa) was a β-xylosidase (BcXyl). The enzyme showed high activity to p-Nitrophenyl-β-d-galactopyranoside (pNPGa) and p-Nitrophenyl-β-d-xylopyranoside (pNPX), while no activity to p-Nitrophenyl-β-d-glucopyranoside (pNPG) or p-Nitrophenyl-β-D-mannopyranoside (pNPM) was seen. The optimum temperature of BcXyl was 40 °C and the optimum pH was 5.0. The enzyme was strongly inhibited by 1 mM D-gluconate and Ag⁺. HPLC (High Performance Liquid Chromatography) analysis showed that BcXyl catalyzed the degradation of an anthocyanin component of B. calycina, and the release of xylose and galactose due to hydrolysis of glycosidic bonds by BcXyl was detected by GC (Gas Chromatography) /MS. A full-length mRNA sequence (2358 bp) of BcXyl (NCBI No. MK411219) was obtained and the deduced protein sequence shared conserved domains with two anthocyanin-β-glycosidases (Bgln and BadGluc, characterized in fungi). BcXyl, Bgln and BadGluc belong to AB subfamily of Glycoside hydrolase family 3. Similar to BcPrx01, an anthocyanin-degradation-related Peroxidase (POD), BcXyl was dramatically activated at the stage at which the rapid anthocyanin degradation occurred. Taken together, we suggest that BcXyl may be the first anthocyanin-β-glycosidase identified in higher plants.

The application of hydrogen-rich water (HRW) can extend the shelf life of fruits and vegetables. This study aims to investigate the effects of HRW on the quality of fresh-cut Gastrodia elata during low-temperature (4°C) storage. The results indicate that HRW treatment inhibited the decrease in weight loss and the increase in respiration rate, and also slowed down the decrease in total acidity and total soluble solids. HRW treatment could reduce the generation of superoxide anions and hydrogen peroxide, enhance the activity and expression of antioxidant-related enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase, and increase the content of non-enzymatic antioxidant substances, ascorbic acid and glutathione, while decreasing the activity and expression of peroxidase and polyphenol oxidase. Furthermore, HRW treatment not only inhibited the reduction in ADP and ATP content and energy charge but also attenuated the increase in AMP content. It also slowed down the decrease in the activities of H⁺-ATPase, succinate dehydrogenase, Ca²⁺-ATPase, and cytochrome C oxidase. In conclusion, these results demonstrate that HRW treatment enhances the energy levels and effectively mitigates oxidative damage, thereby preserving postharvest quality of fresh-cut G. elata.

Rosa roxburghii fruit has a short postharvest shelf life, with rapid declines in quality and antioxidant capacity. This research assessed how phytic acid affects the antioxidant capacity and quality of R. roxburghii fruit while in the postharvest storage period and reveals its potential mechanism of action. The findings suggested that phytic acid treatment inhibits the production of malondialdehyde (MDA) and enhances the activities and expressions of glutathione peroxidase (GPX), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) while decreasing the generation of superoxide anions (O₂^•−) and hydrogen peroxide (H₂O₂). Phytic acid treatment activates the ascorbate–glutathione (AsA-GSH) cycle and enhances the activity and expression of key enzymes in the cycle: ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR). It also increases the levels of non-enzymatic antioxidants, such as ascorbic acid (AsA) and glutathione (GSH), while reducing the production of dehydroascorbic acid (DHA) and oxidized glutathione (GSSG). Moreover, phytic acid treatment enhances the ratios of AsA/DHA and GSH/GSSG, maintaining the reduced state of the fruit. In summary, phytic acid improves antioxidant defense system and activates the AsA-GSH cycle, alleviating oxidative damage and ensuring R. roxburghii fruit quality after harvest.