XET Activity is Found Near Sites of Growth and Cell Elongation in Bryophytes and Some Green Algae: New Insights into the Evolution of Primary Cell Wall Elongation

Abstract

XET activity was shown to be present in all major groups of green plants. These data suggest that an XET-related growth mechanism originated before the evolutionary divergence of the Chlorobionta and open new insights in the evolution of the mechanisms of primary cell wall expansion.

Phylogeny and Molecular Evolution of the Green Algae

“…This has been shown by several studies elucidating the evolution of land plant genes in the green lineage, including actin , cellulose synthase (Roberts & Roberts, 2004;Yin et al, 2009), class III homeodomain-leucine zipper genes (Floyd et al, 2006), MADS-box genes (Tanabe et al, 2005), vacuolar sorting receptors (Becker & Hoef-Emden, 2009), arabinogalactan-like proteins and hemicelluloses (e.g. endotransglucosylase, responsible for cell wall loosening and cell expansion) (Van Sandt et al, 2007;Eder et al, 2008;Fry et al, 2008).…”

“…Although some cell wall components do appear to be land plant innovations, cell wall evolution after the colonization of land appears to be characterized mostly by the elaboration of a pre-existing set of cell wall polysaccharides and the enzymes that synthesize them (e.g. cellulose synthase and wall-remodelling enzymes), rather than substantial innovation (Roberts & Roberts, 2004;Domozych et al, 2007;Van Sandt et al, 2007;Eder et al, 2008;Fry et al, 2008;Domozych et al, 2009;Yin et al, 2009;Popper & Tuohy, 2010;Popper et al, 2011).…”

Structure-Function Analysis of a Broad Specificity Populus trichocarpa Endo-β-glucanase Reveals an Evolutionary Link between Bacterial Licheninases and Plant XTH Gene Products

“…The Charophyta sequence CHARA2 was manually transcribed from Ref. 19, and an expressed sequence tag from Coleochaete nitellarum was obtained from GenBank TM (accession number HO204633). Possible localization and post-translational modifications were analyzed by SignalP (20), ChloroP (21), LipoP (22), and GPP (23).…”

How Have Plant Cell Walls Evolved?

“…In addition to data from immunolabeling and linkage analysis, Fry et al (2008b) have described the activity of an enzyme, mixed-linkage glucan/XyG endotransglucosylase, in certain CGA that grafts MLG to XyG oligosaccharides. Furthermore, XyG endotransglucosylase activity and a putative XyG endotransglucosylase/hydrolase enzyme have been reported in Chara vulgaris (Van Sandt et al, 2007).…”