Abstract:The main pigment that affects flower colors is the anthocyanin, and dihydroflavonol 4-reductase(DFR)is a key enzyme involved in anthocyanin biosynthesis pathway. A full-length gene from brown cotton(Cultivar Xincaimian 6)fiber at the 16 day post anthesis(16 DPA)encoding dihydroflavonol 4-reductase(GhDFR)was isolated, through homology cloning techniques. A full length coding sequence(CDS)and genomic sequence including introns were obtained. Bioinformatics approach was used to analyze and predict the function and structure domain of GhDFR. According to sequence analysis, the genomic sequence of GhDFR contained six exons and five introns. The full-length CDS of the GhDFR ortholog consisted of a 1 500 bp open reading frame(ORF)encoding a polypeptide composed of 355 amino acid residues. The molecular weight of deduced GhDFR polypeptide was 39.65 kD, with an isoelectric point(pI)of 5.67. The deduced amino acid sequence of the GhDFR ortholog had a highly conserved NADP(H)-binding site and substrate specificity site. The deduced DFR amino acid sequence showed high homology with DFRs from other plants, such as Populus trichocarpa, Vitis vinifera and Pelargonium zonale. Phylogenetic analysis showed the closest relationship with DFRs of Pelargonium zonale and Paeonia lactiflora.