Cloning and Characterization of Dihydroflavonol-4-Reductase Gene PtDFR from Populus tomentosa

 The choice of substrate for DFR is an important factor in determining the species of anthocya-nins in plants and determines the proportion of anthocyanins to a large extent, so that the plants end up in different colors. In addition, different members of the DFR gene family have different catalytic efficiencies for substrate, so it determines the types and content of anthocyanins in plants to some extent, therefore affecting the color of plant tissues or organs. In this study, the dihydroflavonol-4-reductase gene was selected as desired gene. Based on the analysis of the existing transcriptome data of Populus tomentosa, we designed a pair of PCR primers, using Populus tomentosa genomic DNA as a template, and obtained one member of the Populus tomentosa DFR gene family by PCR amplification, and named as PtDFR. The sequencing results showed that the full length was 1 519 bp, com-posed of 5 exons and 4 introns. The CDS length was 954 bp, encoding 317 amino acids, containing one conserved domain of NADP(H). Both amino acid similarity and phylogenetic analysis showed that PtDFR with Populus alba L. and Populus trichocarpa is as high as 95.65% and 94.21%, while the DFR amino acid similarity with other 7 species such as Citrus reshni, Zizyphus jujuba, Vitis vinifera reached 89.29%-82.14%. Further transcriptome data analysis showed that the FPKM values of PtDFR presented big differences in tissues and organs. The FPKM value in germinating vegetative buds was the highest, conversely, the lowest in the dormant vegetative buds. The expres-sion trends of PtDFR in male and female flower buds during develoment were similar. The results will lay a good foundation for further studying the function of PtDFR.