Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa
Arabidopsis thaliana T-DNA Mutants Implicate GAUT Genes in the Biosynthesis of Pectin and Xylan in Cell Walls and Seed Testa作者机构：Department of Biochemistry and Molecular Biology University of Georgia Athens GA 30602 USA Complex Carbohydrate Research Center BioEnergy Science Center 315 Riverbend Road University of Georgia Athens GA 30602 USA Department of Plant Biology University of Georgia Athens GA 30602 USA
出 版 物：《Molecular Plant》 (分子植物（英文版）)
年 卷 期：2009年第2卷第5期
页 面：1000-1014页
核心收录：
学科分类：0710[理学-生物学] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 071007[理学-遗传学] 0901[农学-作物学] 0902[农学-园艺学] 10[医学]
主 题：Carbohydrate metabolism cell walls Arabidopsis biosynthesis mutant pectin mucilage
摘 要：Galacturonosyltransferase 1 （GAUT1） is an α1,4-D-galacturonosyltransferase that transfers galacturonic acid from uridine 5＇-diphosphogalacturonic acid onto the pectic polysaccharide homogalacturonan （Sterling et al., 2006）. The 25-member Arabidopsis thaliana GAUT1-related gene family encodes 15 GAUT and 10 GAUT-like （GATL） proteins with, respectively, 56-84 and 42-53% amino acid sequence similarity to GAUT1. Previous phylogenetic analyses of AtGAUTs indicated three clades： A through C. A comparative phylogenetic analysis of the Arabidopsis, poplar and rice GAUT families has sub-classified the GAUTs into seven clades： clade A-1 （GAUTs 1 to 3）; A-2 （GAUT4）; A-3 （GAUTs 5 and 6）; A-4 （GAUT7）; B-1 （GAUTs 8 and 9）; B-2 （GAUTs 10 and 11）; and clade C （GAUTs 12 to 15）. The Arabidopsis GAUTs have a distribution comparable to the poplar orthologs, with the exception of GAUT2, which is absent in poplar. Rice, however, has no orthologs of GAUTs 2 and 12 and has multiple apparent orthologs of GAUTs 1, 4, and 7 compared with eitherArabidopsis or poplar. The cell wall glycosyl residue compositions of 26 homozygous T-DNA insertion mutants for 13 of 15 Arabidopsis GAUTgenes reveal significantly and reproducibly different cell walls in specific tissues of gaut mutants 6, 8, 9, 10, 11, 12, 13, and 14 from that of wild-type Arabidopsis walls. Pectin and xylan polysaccharides are affected by the loss of GAUT function, as demonstrated by the altered galacturonic acid, xylose, rhamnose, galactose, and arabinose composition of distinct gaut mutant walls. The wall glycosyl residue compositional phenotypes observed among the gaut mutants suggest that at least six different biosynthetic linkages in pectins and/or xylans are affected by the lesions in these GAUTgenes. Evidence is also presented to support a role for GAUT11 in seed mucilage expansion and in seed wall and mucilage composition.
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