Cold storage of amber-fleshed black plums triggers anthocyanin biosynthesis and accumulation in fruit flesh, resulting in flesh reddening under low-temperature conditions. bHLH transcription factors have potential functions in response to cold induction and anthocyanin biosynthesis. To investigate the role of bHLH genes, two amber-fleshed and black-skinned cultivars (Prunus salicina Lindl. ‘Friar’ and ‘Angeleno’) were selected as fruit materials to conduct transcriptomic and bioinformatics analyses. Differentially expressed bHLH genes were identified by RNA-seq and validated using qRT-PCR. Ten bHLH genes (five upregulated, five downregulated) showed the most significant expression changes during cold- triggered flesh reddening. We characterized the protein structures of these 10 bHLH members and constructed a phylogenetic tree. Among them, the gene evm.TU.Chr8.2504 (the corresponding protein ID is evm.model.Chr8.2504), named PsbHLH3, was cold-responsive and contains MYB-binding sites. Further experiments involving transient overexpression were performed to validate the function of PsbHLH3 in facilitating anthocyanin biosynthesis. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays demonstrated that PsbHLH3 interacts with PsMYB10.1. Dual-luciferase assay showed that PsbHLH3 promoted the activation of PsMYB10.1 on the promoter of PsUFGT, and consequently augmented the transcription of structural genes related to anthocyanin biosynthesis. The study reveals that cold storage upregulates PsbHLH3, which acts as a molecular switch governing cold-triggered flesh reddening in plum fruit. These findings clarify the regulatory function of PsbHLH3 in cold-triggered anthocyanin biosynthesis in postharvest plums.

Fresh daylily is a traditional characteristic vegetable in China, which has high nutritional and economic value, but it is extremely susceptible to a series of deterioration phenomena. This paper reviews recent studies on the biological changes associated with postharvest senescence in fresh daylily, the underlying physiological and biochemical metabolic mechanisms, the factors affecting postharvest senescence in fresh daylily, and postharvest preservation techniques. We believe that this review will provide a novel idea for understanding the senescence mechanism of fresh daylily and improving its postharvest preservation.

The effect of cold plasma on the composition and diversity of apple surface fungi and endophytes in cold storage was analyzed by high-throughput sequencing. Microbial co-occurrence networks were constructed. The results showed that cold plasma significantly inhibited the elevation of the α diversity of apple surface fungal communities and affected their composition during cold storage, but there were no significant effects of cold plasma on apple endophytic communities. The predominant fungi on the apple surface were unidentified (52.76%), Penicillium (14.70%), Aspergillus (13.80%) and Acremonium (8.33%). Cold plasma reduced the relative abundance of potentially harmful postharvest fungi on the surface of apples such as Penicillium, Aspergillus and Acremonium. The dominant endophytic bacteria of apples were unidentified (80.78%), Staphylococcus (4.23%) and Bacillus (3.13%). Cold plasma decreased the relative abundance of endophytic Staphylococcus, Bacillus and Corynebacterium. The dominant endophytic fungi of apples were unidentified (30.69%), Rhizopus (18.15%), Lysurus (6.56%), Aspergillus (4.38%) and Cutaneotrichosporon (3.26%). Cold plasma caused a significant decrease in the relative abundance of Zygosaccharomyces, Mortierella and Penicillium. The symbiotic networks of surface fungi and endophytic bacteria of ‘Golden Delicious’ apples were more complex, with more key nodes and complex correlations between nodes. Cold plasma could affect the co-occurrence networks of surface fungi and endophytic bacteria, simplifying their structures. But the co-occurrence network of endophytic fungi was simple in structure with less connectivity between nodes.

In this experiment, we used different doses of 1-methylcyclopropene (1-MCP), 2,4-epibrassionolide (EBR), and their combination to treat fresh daylily and conducted a 15-day storage experiment at -1 to 1 ℃. By measuring physicochemical indicators and conducting transcriptomic analysis, the effects of 1-MCP and/or EBR on the postharvest senescence of fresh daylily were studied. The results indicated that combined treatment with 1 μL/L 1-MCP and 1 mg/L EBR after harvest was more effective in delaying adverse changes, such as yellowing, elongation, softening, dispersal, mass loss, and chlorophyll degradation, thereby greatly maintaining the storage quality of fresh daylily. Transcriptomic analysis revealed that the combined treatment regulated the transcription levels of senescence-related genes in daylily; significantly inhibiting the transcription of genes related to the ethylene biosynthesis and signal transduction pathways while activating the transcription of genes related to the brassinolide biosynthesis signal transduction pathway, therefore altering the metabolic balance of growth and senescence hormone levels in daylily. The combined treatment inhibited the transcription of genes related to the chlorophyll degradation pathway, which was beneficial for maintaining the quality of fresh daylily. Additionally, the combined treatment inhibited the transcription of E3 ubiquitin ligase genes closely related to senescence, thereby delaying protein degradation and postponing the physiological process of postharvest senescence in fresh daylily. This study provides a theoretical basis and practical reference for delaying the postharvest senescence and maintaining the storage quality of fresh daylily flower buds.

This study explored the effects of malic acid, citric acid, and their combination on sucrose conversion in a simulated preserved cherry tomato syrup under heating conditions. The results showed that the content of reducing sugar generated by sucrose conversion increased with increasing concentration of the two organic acids and their 1:1 (m/m) mixture. When citric acid and malic acid were combined in a ratio of 2:1 (m/m), the reducing sugar content in the sucrose solution reached its maximum level. During the candying of cherry tomato, the contents of total sugar and sucrose in the syrup decreased with increasing number of boiling cycles, while the contents of reducing sugar, fructose, pectin, and total acid increased. Three deacidification methods and four depectinization methods for the syrup were evaluated. The mass of substances required to deacidify the syrup decreased in the order of calcium carbonate > sodium bicarbonate > calcium hydroxide. The removal rates of pectin from the syrup treated with calcium hydroxide and gelatin and diatomaceous earth were 42.4% and 60.2%, respectively. Calcium hydroxide treatment provided more pronounced removal of pectin under heating conditions than at room temperature, and the effect increased first and then decreased with the increase in pH. Centrifugation effectively increased the light transmittance of the syrup and reduced its pectin content by 24.0%–43.2%. The pectin removal rate after filtration by filter paper or filter membrane was between 32.3% and 34.0%. These findings provide theoretical insights into the conversion of sucrose in preserved cherry tomato syrup and offer practical approaches for the deacidification, depectinization and reuse of the syrup.

In this study, the effect of different intensities of cold plasma (treatment for 10 and 20 min as low and high intensities, respectively) was evaluated on the storage quality and wound healing of Golden Delicious apples damaged by static pressure treatment (at 60 N for 24 h), and unblemished fruits were used as a control. The results showed that cold plasma generated by dielectric barrier discharge (DBD) could produce O₃ and remove C₂H₄, inhibit the respiratory intensity and C₂H₄ release of damaged fruits, delay the decrease in soluble solid content and firmness, and inhibit the increase in the rate of mass loss. Moreover, cold plasma treatment for 10 min had a more pronounced effect while delaying the browning of fruits. The effect of cold plasma treatment for 10 min on the wound healing of damaged apples was also studied. It was found that that low-intensity cold plasma significantly reduced the indentation of the damaged fruits, and resulted in the breakdown and death of surface cells at the wound site and cell wall fragmentation, thereby inhibiting the progression of fruit damage. Low-intensity cold plasma treatment also increased the total phenol content, initially decreased and then increased the activity of polyphenol oxidase (PPO), decreased the activity of peroxidase (POD), and increased the activity of catalase (CAT), thus delaying fruit senescence and consequently exerting a more pronounced wound healing effect. In summary, low-intensity cold plasma treatment can inhibit the quality deterioration of postharvest Golden Delicious apples caused by mechanical injury, thereby improving the marketability of fruits. It can be used as a green and environmentally friendly technology for postharvest storage and preservation of fruits and vegetables.