The content of metal ions in fruits is inseparable from plant intake of trace elements and health effects in the human body. To understand metal ion content in the fruit and pericarp of melon (Cucumis melo L.) and the candidate genes responsible for controlling this process, we analyzed the metal ion content in distinct parts of melon fruit and pericarp and performed RNA-seq. The results showed that the content of metal ions in melon fruit tissue was significantly higher than that in the pericarp. Based on transcriptome expression profiling, we found that the fruit and pericarp contained elevated levels of DEGs. GO functional annotations included cell surface receptor signaling, signal transduction, organic substance metabolism, carbohydrate derivative binding, and hormone-mediated signaling pathways. KEGG pathways included pectate lyase, pentose and glucuronate interconversions, H⁺-transporting ATPase, oxidative phosphorylation, plant hormone signal transduction, and MAPK signaling pathways. We also analyzed the expression patterns of genes and transcription factors involved in hormone biosynthesis and signal transduction. Using weighted gene co-expression network analysis (WGCNA), a co-expression network was constructed to identify a specific module that was significantly correlated with the content of metal ions in melon, after which the gene expression in the module was measured. Connectivity and qRT–PCR identified five candidate melon genes, LOC103501427, LOC103501539, LOC103503694, LOC103504124, and LOC107990281, associated with metal ion content. This study provides a theoretical basis for further understanding the molecular mechanism of heavy metal ion content in melon fruit and peel and provides new genetic resources for the study of heavy metal ion content in plant tissues.

Hydrogel antibacterial agent is an ideal antibacterial material because of its ability to diffuse antibacterial molecules into the decayed area by providing a suitable microenvironment and acting as a protective barrier on the decay interface. The biocompatibility and biodegradation make the removal process easy and it is already widely used in medical fields. However, there have been few reports on its application for controlling postharvest diseases in fruit. In this study, the Chitosan–silver (CS–Ag) complex hydrogels were prepared using the physical crosslinking method, which is used for controlling postharvest diseases in grape. The prepared hydrogels were stable for a long period at room temperature. The structure and surface morphology of CS–Ag composite hydrogels were characterized by UV-Vis, FTIR, SEM, and XRD. The inhibitory effects of CS–Ag hydrogel on disease in grape caused by P. expansum, A. niger, and B. cinerea were investigated both in vivo and in vitro. The remarkable antibacterial activity of CS–Ag hydrogels was mainly due to the combined antibacterial and antioxidant effects of CS and Ag. Preservation tests showed that the CS–Ag hydrogel had positive fresh-keeping effect. This revealed that CS–Ag hydrogels can play a critical role in controlling fungal disease in grapes.

Jujube (Ziziphus jujuba Mill.) is a functional food with both edible and medicinal properties. It is rich in various bioactive compounds and holds significant development value and application prospects in food nutrition, medicine, and health. This review systematically summarizes the research progress on the synthesis mechanism and pharmacological activities of phenolic compounds in jujube fruits, clarifies the composition of their main components, sorts out the research advances in extraction technologies of jujube phenolic compounds, and focuses on analyzing the content differences and distribution patterns across cultivars and tissue parts. On this basis, it examines the regulatory mechanisms of phenolic compound synthesis in depth, with a particular focus on elucidating the regulatory networks of genes and transcription factors involved in flavonoid biosynthesis. Meanwhile, this review comprehensively summarizes the pharmacological activities of phenolic compounds in jujube fruits, including antioxidant, anticancer, antibacterial, anti-inflammatory, and hypoglycemic effects. It also elucidates the molecular mechanisms underlying these bioactivities, such as regulating signaling pathways and scavenging free radicals. Finally, it analyzes the limitations of current research and proposes key directions for future development. This review provides theoretical support and a scientific basis for the in-depth development and utilization of jujube phenolic compounds as well as for the research and development of related functional foods and drugs.

Silver ion (Ag+) are recognized for their potent antibacterial properties; however, their utilization in food preservation is restricted by factors such as inadequate stability, a transient antibacterial impact, and the potential for human absorption. Hydrogel-based antibacterial agents are capable of exerting their antibacterial effects by establishing appropriate microenvironments, which facilitate the efficient delivery of antimicrobial molecules to the contaminated regions of food. In previous studies, we observed that chitosan (CS) and silver nitrate (AgNO3) were able to reduce Ag+ to silver nanoparticles (AgNPs) with enhanced antibacterial properties. This not only significantly extended the stability of the antibacterial agent but also demonstrated exceptional inhibitory capabilities against pathogenic bacteria, including common grape contaminants such as P. expansum, A. niger, and B. cinerea. Utilizing ultrasound-induced complexation technology, this study has successfully synthesized a chitosan-silver (CS-AgNPs) hydrogel. The efficacy of this hydrogel against the pathogenic fungus responsible for jujube black spot disease has been thoroughly investigated. The morphology structures of CS-AgNPs hydrogels were characterized by TEM, FTIR and UV-vis. The results indicated that AgNPs ranging from 80 to 110 nm were uniformly dispersed within the gel matrix and remained stable for extended periods at room temperature. In vitro antibacterial assays and fractional inhibitory concentration index (FICI) studies revealed that the pronounced antibacterial efficacy of the CS-AgNPs hydrogel was primarily attributed to the additive antibacterial effect of CS and AgNPs. These insights underscore the significant potential of CS-AgNPs hydrogels in combating fungal diseases of jujube, offering innovative strategies and materials for the management of agricultural pathogens.

Background: The sensory quality of melon (Cucumis melo L.) is determined by the complex interplay of metabolites within the fruit. However, the underlying metabolic mechanisms based on consumer sensory experience remain underexplored. Methods: Sensory evaluation was conducted on twelve melon cultivars, recording flesh color and quantitatively scoring acidity, sweetness, firmness, and aroma intensity. Based on the sensory results, eight cultivars were selected to establish two contrasting groups: sweet-type vs. acidic-type and orange-fleshed vs. green-fleshed. Untargeted metabolomics (UPLC-QTOF-MS) was then performed to analyze the samples, and differential metabolites were screened using OPLS-DA combined with univariate analysis. Results: Pathway enrichment analysis revealed that the key distinction between sweet and acidic taste profiles was associated with the specific accumulation of citric acid within the tricarboxylic acid (TCA) cycle in the acidic-type group. Regarding flesh color, the orange-fleshed group was enriched with carotenoid derivatives like β-citraurinene and the oxidized tocopherol product α-tocopherolquinone, whereas the green-fleshed group mainly accumulated phytol, a chlorophyll degradation product, along with more abundant terpenoids. Conclusions: By integrating sensory phenotyping with metabolomic analysis, this study identified key differential metabolites and candidate pathways associated with taste and color in melon, providing metabolic insights and data resources for quality evaluation and regulation.