title: Arabidopsis leucine-rich repeat extensin (LRX) proteins modify cell wall composition and influence plant growth.
abstract: BACKGROUND
  Leucine-rich repeat extensins (LRXs) are extracellular proteins consisting of an N-terminal leucine-rich repeat (LRR) domain and a C-terminal extensin domain containing the typical features of this class of structural hydroxyproline-rich glycoproteins (HRGPs). The LRR domain is likely to bind an interaction partner, whereas the extensin domain has an anchoring function to insolubilize the protein in the cell wall. Based on the analysis of the root hair-expressed LRX1 and LRX2 of Arabidopsis thaliana, LRX proteins are important for cell wall development. The importance of LRX proteins in non-root hair cells and on the structural changes induced by mutations in LRX genes remains elusive.
  
  
  RESULTS
  The LRX gene family of Arabidopsis consists of eleven members, of which LRX3, LRX4, and LRX5 are expressed in aerial organs, such as leaves and stem. The importance of these LRX genes for plant development and particularly cell wall formation was investigated. Synergistic effects of mutations with gradually more severe growth retardation phenotypes in double and triple mutants suggest a similar function of the three genes. Analysis of cell wall composition revealed a number of changes to cell wall polysaccharides in the mutants.
  
  
  CONCLUSIONS
  LRX3, LRX4, and LRX5, and most likely LRX proteins in general, are important for cell wall development. Due to the complexity of changes in cell wall structures in the lrx mutants, the exact function of LRX proteins remains to be determined. The increasingly strong growth-defect phenotypes in double and triple mutants suggests that the LRX proteins have similar functions and that they are important for proper plant development.
authors.affiliation: Institute of Plant Biology, University of Zürich, Zollikerstr. 107, Zürich, 8008, Switzerland. christian.draeger@gmx.ch.|Current address: Thermo Fisher Scientific, Neuhofstrasse 11, 4153, Reinach, Switzerland. christian.draeger@gmx.ch.
authors.forename: Christian
authors.initials: C
authors.lastname: Draeger
authors.affiliation: Institute of Plant Biology, University of Zürich, Zollikerstr. 107, Zürich, 8008, Switzerland. nf.tohnyui@botinst.uzh.ch.
authors.forename: Tohnyui
authors.initials: T
authors.lastname: Ndinyanka Fabrice
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318 Saclay Plant Sciences, Versailles, 78026, France. Emilie.Gineau@versailles.inra.fr.|AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318 Saclay Plant Sciences, Versailles, 78026, France. Emilie.Gineau@versailles.inra.fr.
authors.forename: Emilie
authors.initials: E
authors.lastname: Gineau
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318 Saclay Plant Sciences, Versailles, 78026, France. gregory.mouille@versailles.inra.fr.
authors.forename: Grégory
authors.initials: G
authors.lastname: Mouille
authors.affiliation: Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, 94720, USA. benkuhn@gmx.de.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Kuhn
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of Botany, the University of Melbourne, Parkville, Victoria, 3010, Australia. Isabel.Moller@plantandfood.co.nz.|Current address: The New Zealand Institute for Plant & Food Research Limited, Auckland, 1142, New Zealand. Isabel.Moller@plantandfood.co.nz.
authors.forename: Isabel
authors.initials: I
authors.lastname: Moller
authors.affiliation: Institute of Plant Biology, University of Zürich, Zollikerstr. 107, Zürich, 8008, Switzerland. m-t.abdou@bluewin.ch.
authors.forename: Marie-Therese
authors.initials: MT
authors.lastname: Abdou
authors.affiliation: Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland. beat.frey@wsl.ch.
authors.forename: Beat
authors.initials: B
authors.lastname: Frey
authors.affiliation: Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, 94720, USA. mpauly69@berkeley.edu.
authors.forename: Markus
authors.initials: M
authors.lastname: Pauly
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, School of Botany, the University of Melbourne, Parkville, Victoria, 3010, Australia. abacic@unimelb.edu.au.
authors.forename: Antony
authors.initials: A
authors.lastname: Bacic
authors.affiliation: Institute of Plant Biology, University of Zürich, Zollikerstr. 107, Zürich, 8008, Switzerland. chringli@botinst.uzh.ch.
authors.forename: Christoph
authors.initials: C
authors.lastname: Ringli
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006023:Glycoproteins / Q000235:genetics* / Q000378:metabolism; D007930:Leucine / Q000378:metabolism*; D008969:Molecular Sequence Data; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D006023:Glycoproteins; C000606539:LRX3 protein, Arabidopsis; C000606540:LRX4 protein, Arabidopsis; C000606541:LRX5 protein, Arabidopsis; D007930:Leucine