Arabidopsis irregular xylem8andirregular xylem9: Implications for the Complexity of Glucuronoxylan Biosynthesis
- 1 February 2007
- journal article
- Published by Oxford University Press (OUP) in Plant Cell
- Vol. 19 (2), 549-563
- https://doi.org/10.1105/tpc.106.049320
Abstract
Mutations of Arabidopsis thaliana IRREGULAR XYLEM8 (IRX8) and IRX9 were previously shown to cause a collapsed xylem phenotype and decreases in xylose and cellulose in cell walls. In this study, we characterized IRX8 and IRX9 and performed chemical and structural analyses of glucuronoxylan (GX) from irx8 and irx9 plants. IRX8 and IRX9 are expressed specifically in cells undergoing secondary wall thickening, and their encoded proteins are targeted to the Golgi, where GX is synthesized. 1H-NMR spectroscopy showed that the reducing end of Arabidopsis GX contains the glycosyl sequence 4-β-d-Xylp-(1→4)-β-d-Xylp-(1→3)-α-l-Rhap-(1→2)-α-d-GalpA-(1→4)-d-Xylp, which was previously identified in birch (Betula verrucosa) and spruce (Picea abies) GX. This indicates that the reducing end structure of GXs is evolutionarily conserved in woody and herbaceous plants. This sequence is more abundant in irx9 GX than in the wild type, whereas irx8 and fragile fiber8 (fra8) plants are nearly devoid of it. The number of GX chains increased and the GX chain length decreased in irx9 plants. Conversely, the number of GX chains decreased and the chain length heterodispersity increased in irx8 and fra8 plants. Our results suggest that IRX9 is required for normal GX elongation and indicate roles for IRX8 and FRA8 in the synthesis of the glycosyl sequence at the GX reducing end.Keywords
This publication has 51 references indexed in Scilit:
- TheArabidopsis irregular xylem8Mutant Is Deficient in Glucuronoxylan and Homogalacturonan, Which Are Essential for Secondary Cell Wall IntegrityPlant Cell, 2007
- SND1, a NAC Domain Transcription Factor, Is a Key Regulator of Secondary Wall Synthesis in Fibers ofArabidopsisPlant Cell, 2006
- Development and application of a suite of polysaccharide-degrading enzymes for analyzing plant cell wallsProceedings of the National Academy of Sciences, 2006
- Molecular cloning and characterization of a cotton glucuronosyltranferase geneJournal of Plant Physiology, 2005
- A gene expression map of Arabidopsis thaliana developmentNature Genetics, 2005
- A Bifunctional 3,5-Epimerase/4-Keto Reductase for Nucleotide-Rhamnose Synthesis in ArabidopsisPlant Physiology, 2004
- Heparin and Heparan Sulfate BiosynthesisIUBMB Life, 2002
- Fibers. A Model for Studying Cell Differentiation, Cell Elongation, and Cell Wall BiosynthesisPlant Physiology, 2001
- Arabinoxylan biosynthesis: Identification and partial characterization of beta-1,4-xylosyltransferase from wheatPhysiologia Plantarum, 2000
- Properties of a protein-linked glucuronoxylan formed in the plant Golgi apparatusJournal of Experimental Botany, 1994