title: Natural variation in flavonol accumulation in Arabidopsis is determined by the flavonol glucosyltransferase BGLU6.
abstract: Flavonols are colourless secondary metabolites, primarily regarded as UV-protection pigments that are deposited in plants in their glycosylated forms. The glycosylation of flavonols is mainly catalysed by UDP-sugar-dependent glycosyltransferases (UGTs). Although the structures of flavonol glycosides accumulating in Arabidopsis thaliana are known, many genes involved in the ﬂavonol glycosylation pathway are yet to be discovered. The flavonol glycoside profiles of seedlings from 81 naturally occurring A. thaliana accessions were screened using high performance thin layer chromatography. A qualitative variation in flavonol 3-O-gentiobioside 7-O-rhamnoside (F3GG7R) content was identified. Ler × Col-0 recombinant inbred line mapping and whole genome association mapping led to the identification of a glycoside hydrolase family 1-type gene, At1g60270/BGLU6, that encodes a homolog of acyl-glucose-dependent glucosyltransferases involved in the glycosylation of anthocyanins, possibly localized in the cytoplasm, and that is co-expressed with genes linked to phenylpropanoid biosynthesis. A causal single nucleotide polymorphism introducing a premature stop codon in non-producer accessions was found to be absent in the producers. Several other naturally occurring loss-of-function alleles were also identified. Two independent bglu6 T-DNA insertion mutants from the producer accessions showed loss of F3GG7R. Furthermore, bglu6 mutant lines complemented with the genomic Ler BGLU6 gene confirmed that BGLU6 is essential for production of F3GGR7. We have thus identified an accession-specific gene that causes a qualitative difference in flavonol glycoside accumulation in A. thaliana strains. This gene encodes a flavonol 3-O-glucoside: 6″-O-glucosyltransferase that does not belong to the large canonical family of flavonol glycosyltransferases that use UDP-conjugates as the activated sugar donor substrate.
authors.affiliation: Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ishihara
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tohge
authors.affiliation: Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany.
authors.forename: Prisca
authors.initials: P
authors.lastname: Viehöver
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.affiliation: Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Weisshaar
authors.affiliation: Faculty of Biology & CeBiTec, Bielefeld University, 33615 Bielefeld, Germany ralf.stracke@uni-bielefeld.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Stracke
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics; D002874:Chromosome Mapping; D003593:Cytoplasm / Q000378:metabolism; D044948:Flavonols / Q000378:metabolism*; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008040:Genetic Linkage; D056426:Genetic Loci; D014644:Genetic Variation; D018745:Genome, Plant; D055106:Genome-Wide Association Study; D005964:Glucosyltransferases / Q000378:metabolism*; D007178:Inbreeding; D016254:Mutagenesis, Insertional / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D036226:Seedlings / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D044948:Flavonols; C000612158:BGLU6 protein, Arabidopsis; D005964:Glucosyltransferases
keywords: Arabidopsis thaliana; flavonoid; flavonol glucosyltransferase; glycoside hydrolase-type; natural variation; whole genome association mapping.