Lack of α-Xylosidase Activity in Arabidopsis Alters Xyloglucan Composition and Results in Growth Defects1[W][OA]
Xyloglucan is the main hemicellulose in the primary cell walls of most seed plants and is thought to play a role in regulating the separation of cellulose microfibrils during growth. Xylose side chains block the degradation of the backbone, and α-xylosidase activity is necessary to remove them. Two...
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Published in | Plant physiology (Bethesda) Vol. 154; no. 3; pp. 1105 - 1115 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society of Plant Biologists
26.08.2010
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Subjects | |
Online Access | Get full text |
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Summary: | Xyloglucan is the main hemicellulose in the primary cell walls of most seed plants and is thought to play a role in regulating the separation of cellulose microfibrils during growth. Xylose side chains block the degradation of the backbone, and α-xylosidase activity is necessary to remove them. Two Arabidopsis (
Arabidopsis thaliana
) mutant lines with insertions in the α-xylosidase gene
AtXYL1
were characterized in this work. Both lines showed a reduction to undetectable levels of α-xylosidase activity against xyloglucan oligosaccharides. This reduction resulted in the accumulation of XXXG and XXLG in the liquid growth medium of
Atxyl1
seedlings. The presence of XXLG suggests that it is a poor substrate for xyloglucan β-galactosidase. In addition, the polymeric xyloglucan of
Atxyl1
lines was found to be enriched in XXLG subunits, with a concomitant decrease in XXFG and XLFG. This change can be explained by extensive exoglycosidase activity at the nonreducing ends of xyloglucan chains. These enzymes could thus have a larger role than previously thought in the metabolism of xyloglucan. Finally,
Atxyl1
lines showed a reduced ability to control the anisotropic growth pattern of different organs, pointing to the importance of xyloglucan in this process. The promoter of
AtXYL1
was shown to direct expression to many different organs and cell types undergoing cell wall modifications, including trichomes, vasculature, stomata, and elongating anther filaments. |
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Bibliography: | www.plantphysiol.org/cgi/doi/10.1104/pp.110.163212 The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Ignacio Zarra (ignacio.zarra@usc.es). This work was supported by the Ministerio de Educación y Ciencia (grant no. BFU2005–08770–C02–01), the Ministerio de Ciencia y Tecnología (grant no. BFI2003–03626), and the Xunta de Galicia (grant no. PGIDITOPXIC20002PN), Spain. The online version of this article contains Web-only data. Open Access articles can be viewed online without a subscription. |
ISSN: | 0032-0889 1532-2548 |
DOI: | 10.1104/pp.110.163212 |