title: Down-regulation of UDP-arabinopyranose mutase reduces the proportion of arabinofuranose present in rice cell walls.
abstract: Arabinoxylans may account for up to 25% of the mass of grass cell walls. The interactions of these polysaccharides with themselves and with cellulose and lignin is believed to affect the walls physical properties and increase the walls resistance to biochemical conversion to fermentable sugars. Arabinoxylans have a backbone composed of 1,4-linked β-D-xylosyl residues, some of which are substituted at O-2 or O-3 with single arabinofuranosyl (Araf) residues. The Araf residues are likely transferred from UDP-Araf to the xylan backbone by arabinofuranosyltransferases. UDP-Araf is itself formed from UDP-arabinopyranose (UDP-Arap) by UDP-arabinopyranose mutase (UAM). In this study, RNA interference (RNAi) was used to suppress UAM expression in rice plants and thereby reduce the amounts of UDP-Araf available for cell wall synthesis. Several of the transgenic plants had reduced proportions of Araf in their walls together with a decrease in the extent of substitution of the xylan backbone, and a reduction of between 25% and 80% in ferulic acid and p-coumaric acid contents of the cell walls. Those transgenic plants with >25% reduction in the amounts of Araf were dwarfed and infertile.
authors.affiliation: Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Konishi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Aohara
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Igasaki
authors.forename: Noriko
authors.initials: N
authors.lastname: Hayashi
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Akira
authors.initials: A
authors.lastname: Takahashi
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Hirochika
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Iwai
authors.forename: Shinobu
authors.initials: S
authors.lastname: Satoh
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ishii
mesh_terms: D001089:Arabinose / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism*; D003373:Coumaric Acids / Q000378:metabolism; D015536:Down-Regulation; D019751:Intramolecular Transferases / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D030821:Plants, Genetically Modified / Q000378:metabolism; D014539:Uridine Diphosphate Sugars / Q000737:chemistry / Q000378:metabolism
chemical_list: D003373:Coumaric Acids; D010940:Plant Proteins; D014539:Uridine Diphosphate Sugars; C431714:arabinofuranose; C040817:uridine diphosphate arabinose; D001089:Arabinose; D019751:Intramolecular Transferases