ArabidopsisXXT5 gene encodes a putative 1,6-xylosyltransferase that is involved in xyloglucan biosynthesis

Institute for Integrative Genome Biology, Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
The Plant Journal (Impact Factor: 5.97). 07/2008; 56(1):101-15. DOI: 10.1111/j.1365-313X.2008.03580.x
Source: PubMed


The function of a putative xyloglucan xylosyltransferase from Arabidopsis thaliana (At1g74380; XXT5) was studied. The XXT5 gene is expressed in all plant tissues, with higher levels of expression in roots, stems and cauline leaves. A T-DNA insertion in the XXT5 gene generates a readily visible root hair phenotype (root hairs are shorter and form bubble-like extrusions at the tip), and also causes the alteration of the main root cellular morphology. Biochemical characterization of cell wall polysaccharides isolated from xxt5 mutant seedlings demonstrated decreased xyloglucan quantity and reduced glucan backbone substitution with xylosyl residues. Immunohistochemical analyses of xxt5 plants revealed a selective decrease in some xyloglucan epitopes, whereas the distribution patterns of epitopes characteristic for other cell wall polysaccharides remained undisturbed. Transformation of xxt5 plants with a 35S::HA-XXT5 construct resulted in complementation of the morphological, biochemical and immunological phenotypes, restoring xyloglucan content and composition to wild-type levels. These data provide evidence that XXT5 is a xyloglucan alpha-1,6-xylosyltransferase, and functions in the biosynthesis of xyloglucan.

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Available from: Michael G Hahn, Dec 21, 2014
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    • "The xxt mutants did not label with LM15 or LM25, antibodies specific for xyloglucan epitopes. Genetic analysis of xxt1 and xxt2 mutants has shown that xyloglucan synthesis is required for root hair growth [42, 49]. In addition, similar amounts of xyloglucan can be detected within the walls of wt and single xxt1 and xxt2 mutant seedlings using OLIMP analysis, suggesting that these two loci compensate for one other during xyloglucan synthesis [42]. "
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    • "mutant showed that it displays comparable cell wall changes to xxt1 xxt2 mutant plants (Zabotina et al., 2008), XXT1 and XXT2 having previously being implicated in xyloglucan biosynthesis. Nowadays, the three genes are known to codify xyloxyltransferases involved in xyloglucan biosynthesis (Pauly et al., 2013). "
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    • "Expansion results from complex mechanisms, and the ability of cell walls to extend is both important and potentially restrictive (Wolf et al., 2012). Expansion requires cell wall loosening, which involves modification and remodeling of cell wall components and biosynthesis 2008; Zabotina et al., 2008; Günl et al., 2011). Plant plasticity and compensation mechanisms may account for the lack of apparent phenotypes. "
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