Arabidopsis leucine-rich repeat extensin (LRX) proteins modify cell wall composition and influence plant growth

Abstract

BackgroundLeucine-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.ResultsThe 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.ConclusionsLRX3, 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0548-8) contains supplementary material, which is available to authorized users.

Neuronal apoptosis inhibitory protein (NAIP) localizes to the cytokinetic machinery during cell division

“…Interestingly, in fission yeast53 and in the slime mold Dictyostelium discoidea 54, LRR containing proteins have been associated with cytokinesis. Similarly, plant LRR proteins have been linked to cytokinesis as well55565758.…”

Insights into the Evolution of Hydroxyproline-Rich Glycoproteins from 1000 Plant Transcriptomes

“…In contrast, relatively little is known about the origin and evolution of the hydroxyproline-rich glycoproteins (HRGPs), a major group of wall glycoproteins, despite their widespread occurrence (Supplemental Table S1) and importance in plant growth and development (for review, see Fincher et al, 1983;Kieliszewski and Lamport, 1994;MajewskaSawka and Nothnagel, 2000;Ellis et al, 2010;Lamport et al, 2011;Draeger et al, 2015;Velasquez et al, 2015;Showalter and Basu, 2016). Examination of these glycoproteins in a wider range of plant species should provide valuable insights into how they have evolved in parallel with the polysaccharide components in plant walls.…”

Pipeline to Identify Hydroxyproline-Rich Glycoproteins

“…Chlamydomonas reinhardtii, 30% [w/w]; Roberts, 1974;Voigt et al, 2009), yet they are generally a minor component of land plant (embryophyte) walls (approximately 10% [w/w] in primary walls but less in secondary walls). Despite their low abundance in land plants, selected HRGPs have been shown to play important functional roles in, but not limited to, cell expansion, root growth and development, xylem differentiation, somatic embryogenesis, initiation of female gametogenesis, self-incompatibility, signaling, salt tolerance, and pathogen responses, (for review, see Fincher et al, 1983;Kieliszewski and Lamport, 1994;Majewska-Sawka and Nothnagel, 2000;Seifert and Roberts, 2007;Ellis et al, 2010;Lamport et al, 2011;Draeger et al, 2015;Velasquez et al, 2015;Basu, 2016a, 2016b). Not surprisingly, HRGPs have both fascinated and challenged researchers for decades.…”