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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    ABSTRACT: Background The Arabidopsis root hair represents a valuable cell model for elucidating polar expansion mechanisms in plant cells and the overall biology of roots. The deposition and development of the cell wall is central to the root hair expansion apparatus. During this process, incorporation of specific wall polymers into the growing wall architecture constitutes a critical spatio-temporal event that controls hair size and growth rate and one that is closely coordinated with the cell’s endomembrane, cytoskeletal and signal transduction apparatuses. Results In this study, the protocol for live cell labeling of roots with monoclonal antibodies that bind to specific wall polymers is presented. This method allows for rapid assessment of root hair cell wall composition during development and assists in describing changes to cell wall composition in transgenic mutant lines. Enzymatic “unmasking” of specific polymers prior to labeling allows for refined interpretation of cell wall chemistry. Live cell immunofluorescence data may also be correlated with transmission electron microscopy-based immunogold labeling. Conclusions Live Arabidopsis root hairs may be labeled with cell wall polymer-specific antibodies. This methodology allows for direct visualization of cell wall dynamics throughout development in stable transgenic plant lines. It also provides an important new tool in the elucidation of the specific interactions occurring between membrane trafficking networks, cytoskeleton and the cell wall deposition/remodeling mechanism.
    Plant Methods 10/2014; 10(1):30. DOI:10.1186/1746-4811-10-30 · 3.10 Impact Factor
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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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    Frontiers in Plant Science 06/2014; 5:303. DOI:10.3389/fpls.2014.00303 · 3.95 Impact Factor
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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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    ABSTRACT: Cell expansion is an increase in cell size and thus plays an essential role in plant growth and development. Phytohormones and the primary plant cell wall play major roles in the complex process of cell expansion. In shoot tissues, cell expansion requires the auxin receptor AUXIN BINDING PROTEIN1 (ABP1), but the mechanism by which ABP1 affects expansion remains unknown. We analyzed the effect of functional inactivation of ABP1 on transcriptomic changes in dark-grown hypocotyls and investigated the consequences of gene expression on cell wall composition and cell expansion. Molecular and genetic evidence indicates that ABP1 affects the expression of a broad range of cell wall-related genes, especially cell wall remodeling genes, mainly via an SCF(TIR/AFB)-dependent pathway. ABP1 also functions in the modulation of hemicellulose xyloglucan structure. Furthermore, fucosidase-mediated defucosylation of xyloglucan, but not biosynthesis of nonfucosylated xyloglucan, rescued dark-grown hypocotyl lengthening of ABP1 knockdown seedlings. In muro remodeling of xyloglucan side chains via an ABP1-dependent pathway appears to be of critical importance for temporal and spatial control of cell expansion.
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