To explore the impact of shade treatment on grape berries, ‘Marselan’ grape berries were bagged under different light transmission rates (100% (CK), 75% (A), 50% (B), 25% (C), 0% (D)). It was observed that this treatment delayed the ripening of the grape berries. The individual weight of the grape berries, as well as the content of fructose, glucose, soluble sugars, and organic acids in the berries, was measured at 90, 100, and 125 days after flowering (DAF90, DAF100, DAF125). The results revealed that shading treatment reduced the sugar content in grape berries; the levels of fructose and glucose were higher in the CK treatment compared to the other treatments, and they increased with the duration of the shading treatment. Conversely, the sucrose content exhibited the opposite trend. Additionally, as the weight of the grape berries increased, the content of soluble solids and soluble sugars in the berries also increased, while the titratable acidity decreased. Furthermore, 16 differentially expressed genes (DEGs) were identified in the photosynthesis-antenna protein pathway from the transcriptome sequencing data. Correlation analysis revealed that the expression levels of genes VIT_08s0007g02190 (Lhcb4) and VIT_15s0024g00040 (Lhca3) were positively correlated with sugar content in the berries at DAF100, but negatively correlated at DAF125. qRT-PCR results confirmed the correlation analysis. This indicates that shading grape clusters inhibits the expression of genes in the photosynthesis-antenna protein pathway in the grape berries, leading to a decrease in sugar content. This finding contributes to a deeper understanding of the impact mechanisms of grape cluster shading on berry quality, providing important scientific grounds for improving grape berry quality.

Dihydroflavonol 4-reductase (DFR) significantly influences the modification of flower color. To explore the role of DFR in the synthesis of strawberry anthocyanins, in this study, we downloaded the CDS sequences of the DFR gene family from the Arabidopsis genome database TAIR; the DFR family of forest strawberry was compared; then, a functional domain screen was performed using NCBI; the selected strawberry DFR genes were analyzed; and the expression characteristics of the family members were studied by qRT-PCR. The results showed that there are 57 members of the DFR gene family in strawberry, which are mainly expressed in the cytoplasm and chloroplast; most of them are hydrophilic proteins; and the secondary structure of the protein is mainly composed of α-helices and random coils. The analysis revealed that FvDFR genes mostly contain light, hormone, abiotic stress, and meristem response elements. From the results of the qRT-PCR analysis, the relative expression of each member of the FvDFR gene was significantly different, which was expressed throughout the process of fruit coloring. Most genes had the highest expression levels in the full coloring stage (S4). The expression of FvDFR30, FvDFR54, and FvDFR56 during the S4 period was 8, 2.4, and 2.4 times higher than during the S1 period, indicating that the DFR gene plays a key role in regulating the fruit coloration of strawberry. In the strawberry genome, 57 members of the strawberry DFR gene family were identified. The higher the DFR gene expression, the higher the anthocyanin content, and the DFR gene may be the key gene in anthocyanin synthesis. Collectively, the DFR gene is closely related to fruit coloring, which lays a foundation for further exploring the function of the DFR gene family.

Clonal selection is essential for adapting wine production to specific terroirs. To characterize clonal variation in berry quality, five ‘Merlot’ clones (M343, VCR1, VCR3, VCR13, and VCR101) grown in the Hexi Corridor region of Gansu Province, China, were evaluated during the 2024 growing season. An integrated analysis of morphological, physicochemical, phenolic, metabolomic, and volatile traits was conducted to provide a multidimensional assessment of clone-specific berry quality under the arid conditions of this region. VCR1 exhibited the highest total soluble solids and anthocyanin contents, alongside the largest number of annotated metabolites. VCR101 had the highest titratable acidity and the most diverse flavonoid profile, whereas VCR13 showed the highest total soluble sugar content. VCR3 had the highest tannin and total phenolic contents and also exhibited the greatest number and total semi-quantitative relative abundance of volatile compounds. These findings demonstrate that, under arid conditions, the clones differ in their accumulation patterns of sugars, organic acids, phenolics, and aroma-related metabolites. Exploratory principal component analysis identified VCR3 and VCR1 as promising candidates for production objectives emphasizing different quality attributes. These findings provide practical information for clonal selection, germplasm evaluation, wine grape breeding, and region-specific cultivation under arid environmental conditions.