title: Molecular characterization and expression analysis of dihydroflavonol 4-reductase (DFR) gene in Saussurea medusa.
abstract: Dihydroflavonol 4-reductase (DFR), which catalyzes the reduction of dihydroflavonols to leucoanthocyanins, is a key enzyme in the biosynthesis of anthocyanidins, proanthocyanidins, and other flavonoids of importance in plant development and human nutrition. This study isolated a full length cDNA encoding DFR, designated as SmDFR (GenBank Accession No. EF600682), by screening a cDNA library from a red callus line of Saussurea medusa, which is an endangered, traditional Chinese medicinal plant with high pharmacological value. SmDFR was functionally expressed in yeast (Saccharomyces cerevisiae) to confirm that SmDFR can readily reduce dihydroquercetin (DHQ) and dihydrokampferol (DHK), but it could not reduce dihydromyricetin (DHM). The deduced SmDFR structure shared extensive sequence similarity with previously characterized plant DFRs and phylogenetic analysis showed that it belonged to the plant DFR super-family. SmDFR also possessed flavanone 4-reductase (FNR) activity and can catalyze the conversion of eridictyol to luteoforol. Real-time PCR analysis showed that the expression level of SmDFR was higher in flowers compared with both leaves and roots. This work greatly enhances our knowledge of flavonoid biosynthesis in S. medusa and marks a major advance that could facilitate future genetic modification of S. medusa.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Houhua
authors.initials: H
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Qiu
authors.forename: Fudong
authors.initials: F
authors.lastname: Chen
authors.forename: Xiaofen
authors.initials: X
authors.lastname: Lv
authors.forename: Chunxiang
authors.initials: C
authors.lastname: Fu
authors.forename: Dexiu
authors.initials: D
authors.lastname: Zhao
authors.forename: Xuejun
authors.initials: X
authors.lastname: Hua
authors.forename: Qiao
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D056727:Endangered Species; D004926:Escherichia coli; D005419:Flavonoids / Q000378:metabolism; D044948:Flavonols / Q000378:metabolism; D035264:Flowers / Q000378:metabolism; D020869:Gene Expression Profiling; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010802:Phylogeny; D011794:Quercetin / Q000031:analogs & derivatives / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae; D030441:Saussurea / Q000201:enzymology*; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D005419:Flavonoids; D044948:Flavonols; C080220:aromadedrin; D011794:Quercetin; C003377:taxifolin; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase; C472036:dihydromyricetin