The performance of p-Anisaldehyde (PAA) for preserving pitaya fruit quality and the underpinning regulatory mechanism were investigated in this study. Results showed that PAA treatment significantly reduced fruit decay, weight loss and loss of firmness, and maintained higher content of total soluble solids, betacyanins, betaxanthins, total phenolics and flavonoids in postharvest pitaya fruits. Compared with control, the increase in hydrogen peroxide (H₂O₂) content and superoxide anion (O₂^•−) production was inhibited in fruit treated with PAA. Meanwhile, PAA significantly improved the activity of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Moreover, PAA-treated pitaya fruit maintained higher ascorbic acid (AsA) and reduced-glutathione (GSH) content but lower dehydroascorbate (DHA) and oxidized glutathione (GSSG) content, thus sustaining higher ratio of AsA/DHA and GSH/GSSG. In addition, activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydrogenation ascorbic acid reductase (DHAR), as well as the expression of HpSOD, HpPOD, HpCAT, HpAPX, HpGR, HpDHAR and HpMDHAR, were enhanced after PAA treatment. The findings suggest that postharvest application of PAA may be a reliable method to control postharvest decay and preserve quality of harvested pitaya fruit by enhancing the antioxidant potential of the AsA-GSH cycle and activating an antioxidant defense system to alleviate reactive oxygen species (ROS) accumulation.

In this study, the impact of modified atmosphere packaging (MAP) on quality, lignin biosynthesis, reactive oxygen species (ROS) metabolism, and microstructures of stem in Chinese flowering cabbages was investigated. Compared with control, MAP treatment retained higher content of protein, total soluble solid, and vitamin C, while lower weight loss rate, carbon dioxide (CO₂) production rate, electrolyte leakage, firmness and hollowing of stems. Lignin content in MAP-treated stems was 1.23-fold higher than that of control stems on the twelfth day. Moreover, MAP treatment inhibited the increasing in cell wall thickness by inhibiting activities of lignin biosynthesis-related enzymes. In addition, MAP suppressed ROS contents, while enhanced levels of ascorbic acid and reduced glutathione through promoting activities of antioxidant enzymes. The above results suggest that maintaining stems quality of Chinese flowering cabbages through MAP treatment is related to prevent lignin accumulation around the vascular tissue and enhance antioxidant capacity.

Soluble sugar is one of the most important factors affecting fruit flavor and quality. Here, we report the identification of two Dof (DNA-binding with one finger) transcription factors termed HpDof1.7 and HpDof5.4 and their roles in influencing sugar accumulation in pitayas. HpDof1.7 and HpDof5.4 share a similar expression pattern with sugar metabolism-related genes HpSuSy1 and HpINV2, and sugar transporter genes HpTMT2 and HpSWEET14 during pitayas maturation, and their expression pattern was also consistent with the accumulation of glucose and fructose, which were the predominant sugars in pitayas. HpDof1.7 and HpDof5.4 were both typical nucleus-localized proteins with trans-activation ability. Gel mobility shift assay revealed that HpDof1.7 and HpDof5.4 were bound to promoters of HpSuSy1, HpINV2, HpTMT2 and HpSWEET14. Finally, transient expression assays in tobacco leaves showed that HpDof1.7 and HpDof5.4 increased the activities of HpSuSy1, HpINV2, HpTMT2 and HpSWEET14 promoters, thus facilitating sugar accumulation by transcriptionally enhancing sugar metabolic pathway genes. Our findings provide a new perspective on the regulatory mechanisms of Dof transcription factors in sugar accumulation and pitaya fruit quality formation.

Postharvest grapes exhibit a limited shelf life due to susceptibility to rot and deterioration, significantly reducing their nutritional and economic value. Sulfur dioxide (SO₂) is a widely recognized preservative for extending grape storage life. This study performed a detailed analysis of ‘Munage’ table grapes treated with SO₂ fumigation, employing transcriptomic and metabolomic approaches. Results indicate that SO₂ fumigation significantly extends the shelf life of grapes, as demonstrated by improved visual quality, reduced decay rates, and increased fruit firmness. We identified 309 differentially accumulated metabolites (DAMs) and 1906 differentially expressed genes (DEGs), including 135 transcription factors (TFs). Both DEGs and DAMs showed significant enrichment of flavonoid-related metabolism compared with the control, and the relative content of four flavonoid metabolites (Wogonin-7-O-glucuronide, Acacetin-7-O-glucuronide, Apigenin-7-O-glucuronide, and Baicalein 7-O-glucuronide) were significantly increased in grapes upon SO₂ treatment, suggesting that SO₂ treatment had a substantial regulatory effect on grape flavonoid metabolism. Importantly, we constructed complex regulatory networks by screening key enzyme genes (e.g., PAL, 4CLs, CHS, CHI2, and UGT88F3) related to the metabolism of target flavonoid, as well as potential regulatory transcription factors (TFs). Overall, our findings offer new insights into the regulatory mechanisms by which SO₂ maintains the postharvest quality of table grapes.