title: Characterization of IRX10 and IRX10-like reveals an essential role in glucuronoxylan biosynthesis in Arabidopsis.
abstract: Xylan, the major hemicellulosic polysaccharide in Arabidopsis secondary cell walls, requires a number of glycosyltransferases (GT) to catalyse formation of the various glycosidic linkages found in the polymer. In this study, we characterized IRX10 and IRX10-like (IRX10-L), two highly homologous genes encoding members of the glycosyltransferase family 47 (GT47). T-DNA insertions in IRX10 gave a mild irregular xylem (irx) phenotype consistent with a minor defect in secondary cell-wall synthesis, whereas plants containing mutations in IRX10-L showed no change. However, irx10 irx10-L double mutant plants showed a much more severe irx and whole-plant phenotype, suggesting considerable functional redundancy between these two genes. Detailed biochemical analysis of the irx10 irx10-L double mutant showed a large reduction of xylan in the secondary cell walls, consistent with a specific defect in xylan biosynthesis. Furthermore, the irx10 irx10-L mutant retains the unique oligosaccharide found at the reducing end of Arabidopsis xylan, but shows a severe reduction in beta(1,4) xylosyltransferase activity. These characteristics are similar to those of irx9 and irx14, mutants that are believed to be defective in xylan chain elongation, and suggests that IRX10 and IRX10-L also play a role in elongation of the xylan backbone.
authors.affiliation: Faculty of Life Science, University of Manchester, Manchester M13 9PT, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Brown
authors.forename: Zhinong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Elaine
authors.initials: E
authors.lastname: Stephens
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.forename: Simon R
authors.initials: SR
authors.lastname: Turner
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009154:Mutation; D010430:Pentosyltransferases / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D014990:Xylans / Q000032:analysis / Q000096:biosynthesis*; D000097608:UDP Xylose-Protein Xylosyltransferase
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D018744:DNA, Plant; D016695:Glycosyltransferases; D010430:Pentosyltransferases; D014990:Xylans; D000097608:UDP Xylose-Protein Xylosyltransferase; C036483:T-DNA; C038910:glucuronoxylan