The Genome-Wide Identification of the Dihydroflavonol 4-Reductase (DFR) Gene Family and Its Expression Analysis in Different Fruit Coloring Stages of Strawberry

Dihydroflavonol 4-reductase (DFR) significantly influences the modification of flower color. To explore the role of <i>DFR</i> in the synthesis of strawberry anthocyanins, in this study, we downloaded the CDS sequences of the <i>DFR</i> gene family from the <i>Arabidopsis</i> 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 <i>FvDFR</i> 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 <i>FvDFR</i> 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 <i>FvDFR30</i>, <i>FvDFR54</i>, and <i>FvDFR56</i> during the S4 period was 8, 2.4, and 2.4 times higher than during the S1 period, indicating that the <i>DFR</i> gene plays a key role in regulating the fruit coloration of strawberry. In the strawberry genome, 57 members of the strawberry <i>DFR</i> gene family were identified. The higher the <i>DFR</i> gene expression, the higher the anthocyanin content, and the <i>DFR</i> gene may be the key gene in anthocyanin synthesis. Collectively, the <i>DFR</i> gene is closely related to fruit coloring, which lays a foundation for further exploring the function of the <i>DFR</i> gene family.