title: UDP-arabinopyranose mutase 3 is required for pollen wall morphogenesis in rice (Oryza sativa).
abstract: l-Arabinose is one of the main constituents of cell wall polysaccharides such as pectic rhamnogalacturonan I (RG-I), glucuronoarabinoxylans and other glycoproteins. It is found predominantly in the furanose form rather than in the thermodynamically more stable pyranose form. UDP-L-arabinofuranose (UDP-Araf), rather than UDP-L-arabinopyranose (UDP-Arap), is a sugar donor for the biosynthesis of arabinofuranosyl (Araf) residues. UDP-arabinopyranose mutases (UAMs) have been shown to interconvert UDP-Araf and UDP-Arap and are involved in the biosynthesis of polysaccharides including Araf. The UAM gene family has three members in Oryza sativa. Co-expression network in silico analysis showed that OsUAM3 expression was independent from OsUAM1 and OsUAM2 co-expression networks. OsUAM1 and OsUAM2 were expressed ubiquitously throughout plant development, but OsUAM3 was expressed primarily in reproductive tissue, particularly at the pollen cell wall formation developmental stage. OsUAM3 co-expression networks include pectin catabolic enzymes. To determine the function of OsUAMs in reproductive tissues, we analyzed RNA interference (RNAi)-knockdown transformants (OsUAM3-KD) specific for OsUAM3. OsUAM3-KD plants grew normally and showed abnormal phenotypes in reproductive tissues, especially in terms of the pollen cell wall and exine. In addition, we examined modifications of cell wall polysaccharides at the cellular level using antibodies against polysaccharides including Araf. Immunolocalization of arabinan using the LM6 antibody showed low levels of arabinan in OsUAM3-KD pollen grains. Our results suggest that the function of OsUAM3 is important for synthesis of arabinan side chains of RG-I and is required for reproductive developmental processes, especially the formation of the cell wall in pollen.
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Minako
authors.initials: M
authors.lastname: Sumiyoshi
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Inamura
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Nakamura
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Aohara
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ishii
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Satoh
authors.affiliation: University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, 305-8572 Japan iwai.hiroaki.gb@u.tsukuba.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Iwai
mesh_terms: D001089:Arabinose / Q000031:analogs & derivatives* / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D019751:Intramolecular Transferases / Q000378:metabolism*; D009024:Morphogenesis; D009928:Organ Specificity; D012275:Oryza / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D010641:Phenotype; D030821:Plants, Genetically Modified; D011058:Pollen / Q000166:cytology* / Q000201:enzymology* / Q000648:ultrastructure; D034622:RNA Interference; D012098:Reproduction
chemical_list: C431714:arabinofuranose; D001089:Arabinose; D019751:Intramolecular Transferases
keywords: Arabinan; Intine; Pectin; Pollen; Rice; UDP-arabinopyranose mutase