title: Cloning and characterization of soybean gene Fg1 encoding flavonol 3-O-glucoside/galactoside (1→6) glucosyltransferase.
abstract: Flavonoids are important secondary metabolites in plants. Sugar-sugar glycosyltransferases are involved in the final step of flavonoid biosynthesis and contribute to the structural diversity of flavonoids. This manuscript describes the first cloning of a sugar-sugar glucosyltransferase gene in the UGT family that attaches glucose to the 6″-position of sugar bound to a flavonol. The results provide a glimpse on the possible evolution of sugar-sugar glycosyltransferase genes and identify putative amino acids responsible for the recognition of the hydroxyl group of the sugar moiety and specification of sugar. A scheme for the genetic control of flavonol glycoside biosynthesis is proposed. Flavonol glycosides (FGs) are predominant in soybean leaves and they show substantial differences among genotypes. In previous studies, we identified two flavonoid glycoside glycosyltransferase genes that segregated in recombinant inbred lines developed from a cross between cultivars Nezumisaya and Harosoy; one was responsible for the attachment of glucose to the 2″-position of glucose or galactose that is bound to the 3-position of kaempferol and the other was involved in the attachment of glucose to the 6″-position. This study was conducted to clone and characterize the 6″-glucosyltransferase gene. Linkage mapping indicated that the gene was located in the molecular linkage group I (chromosome 20). Based on the genome sequence, we cloned a candidate cDNA, GmF3G6"Gt from Harosoy but the corresponding cDNA could not be amplified by PCR from Nezumisaya. The coding region of GmF3G6″Gt in Harosoy is 1386 bp long encoding 462 amino acids. This gene was not expressed in leaves of Nezumisaya. The GmF3G6″Gt recombinant protein converted UDP-glucose and kaempferol 3-O-glucoside or kaempferol 3-O-galactoside to kaempferol 3-O-glucosyl-(1→6)-glucoside or kaempferol 3-O-glucosyl-(1→6)-galactoside, respectively. These results indicate that GmF3G6″Gt encodes a flavonol 3-O-glucoside/galactoside (1→6) glucosyltransferase and corresponds to the Fg1 gene. GmF3G6″Gt had an amino acid similarity of 82 % with GmF3G6″Rt encoding flavonol 3-O-glucoside/galactoside (1→6) rhamnosyltransferase, suggesting a recent evolutionary divergence of the two genes. This may be the first cloning of a sugar-sugar glucosyltransferase gene in the UGT family that attaches glucose to the 6″-position of sugar bound to a flavonol. A scheme for the control of FG biosynthesis is proposed.
authors: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8518, Japan.|Universidad Católica de Oriente, Rionegro, Antioquia, Colombia.
authors: Felipe
authors: F
authors: Rojas Rodas
authors: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8518, Japan.|Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, People's Republic of China.
authors: Shaokang
authors: S
authors: Di
authors: Department of Botany, National Museum of Nature and Science, Tsukuba, Ibaraki, 305-0005, Japan.
authors: Yoshinori
authors: Y
authors: Murai
authors: Department of Botany, National Museum of Nature and Science, Tsukuba, Ibaraki, 305-0005, Japan.
authors: Tsukasa
authors: T
authors: Iwashina
authors: The RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
authors: Satoko
authors: S
authors: Sugawara
authors: The RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
authors: Tetsuya
authors: T
authors: Mori
authors: The RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
authors: Ryo
authors: R
authors: Nakabayashi
authors: The RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
authors: Keiko
authors: K
authors: Yonekura-Sakakibara
authors: The RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
authors: Kazuki
authors: K
authors: Saito
authors: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8518, Japan. masako@affrc.go.jp.|NARO Institute of Crop Science, Tsukuba, Ibaraki, 305-8518, Japan. masako@affrc.go.jp.
authors: Ryoji
authors: http://orcid.org/0000-0003-0619-1066
authors: R
authors: Takahashi
mesh_terms: D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D005964:Glucosyltransferases; C023249:flavonol 3-O-glucosyltransferase
keywords: Fg1 gene; Flavonol; Flavonol 3-O-glucoside/galactoside (1→6) glucosyltransferase; Glucosyltransferase; Soybean