Journal Article

Xyloglucan Endotransglucosylase Activity Loosens a Plant Cell Wall

Vicky S. T. Van Sandt, Dmitry Suslov, Jean-Pierre Verbelen and Kris Vissenberg

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 100, issue 7, pages 1467-1473
Published in print December 2007 | ISSN: 0305-7364
Published online October 2007 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcm248
Xyloglucan Endotransglucosylase Activity Loosens a Plant Cell Wall

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Plant cells undergo cell expansion when a temporary imbalance between the hydraulic pressure of the vacuole and the extensibility of the cell wall makes the cell volume increase dramatically. The primary cell walls of most seed plants consist of cellulose microfibrils tethered mainly by xyloglucans and embedded in a highly hydrated pectin matrix. During cell expansion the wall stress is decreased by the highly controlled rearrangement of the load-bearing tethers in the wall so that the microfibrils can move relative to each other. Here the effect was studied of a purified recombinant xyloglucan endotransglucosylase/hydrolase (XTH) on the extension of isolated cell walls.

Methods

The epidermis of growing onion (Allium cepa) bulb scales is a one-cell-thick model tissue that is structurally and mechanically highly anisotropic. In constant load experiments, the effect of purified recombinant XTH proteins of Selaginella kraussiana on the extension of isolated onion epidermis was recorded.

Key Results

Fluorescent xyloglucan endotransglucosylase (XET) assays demonstrate that exogeneous XTH can act on isolated onion epidermis cell walls. Furthermore, cell wall extension was significantly increased upon addition of XTH to the isolated epidermis, but only transverse to the net orientation of cellulose microfibrils.

Conclusions

The results provide evidence that XTHs can act as cell wall-loosening enzymes.

Keywords: XTH; XET activity; primary cell wall; xyloglucan; cellulose microfibrils; cellulose orientation; cell expansion; cell wall loosening; extensiometry; onion (Allium cepa); Selaginella kraussiana

Journal Article.  4879 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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