Cloning of Flavonoid 3'-hydroxylase Gene (GhF3'H) and Expressional Characteristics of Several Genes Associated with Pigment Synthesis in Brown Cotton (Gossypium hirsutum L.) Fibers
Abstract：The purpose of this research is to explore the role of anthocyanidin synthesis pathway in pigmentation of brown cotton fibers. Two full-length cDNAs encoding flavonoid 3' -hydroxylase gene (F3'H) was cloned from XC-5 fibers of 16 days post anthesis (DPA) by rapid amplification of cDNA ends (RACE) and RT-PCR using specific primers based on the Gossypium hirsutum EST sequences(GenBank accession: DT545210, CO071403 and BG447485)from the blast results with the full-length cDNA of F3'H in Vitis vinifera that had already known and were named as GhF3'H-1 and GhF3'H-2 (GenBank accession: HM598123, HM598124). The length of the two cDNA sequences were 1 761 and 1 892 bp, respectively. They contained an identical opening reading frame (ORF) of 1 533 bp, encoding a protein of 510 amino acids. There were few differences between the two sequences except for the sequence length of the 3' untranslational region (UTR). The temporal and spatial expression patterns of chalcone synthase (CHS), flavonoid-3’，5'-hydroxylase as (F3'5'H) and flavonoid 3'-hydroxylase (F3'H) genes were examined by the semi-quantitative RT-PCR analysis with the specific primers. The expression analysis indicated that the expressed levels of CHS and F3'5'H gene in white and brown-fiber cotton cultivars during development were relatively high. But the F3'H gene was mainly express in the ovule of 1 day post anthesis, and were almost not expressed in the fibers and petals. All the results suggest that the production of pigments in brown cotton fibers is related to the biosynthesis pathway of anthocyanins, the principle of pigment formation in colored cotton has been disclosed, and this is of help to improve the colors of naturally colored cotton
