Journal Article

Xyloglucan <i>Endo</i>-transglycosylase (XET) Functions in Gelatinous Layers of Tension Wood Fibers in Poplar—A Glimpse into the Mechanism of the Balancing Act of Trees

Nobuyuki Nishikubo, Tatsuya Awano, Alicja Banasiak, Veronica Bourquin, Farid Ibatullin, Ryo Funada, Harry Brumer, Tuula T. Teeri, Takahisa Hayashi, Björn Sundberg and Ewa J. Mellerowicz

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 6, pages 843-855
Published in print June 2007 | ISSN: 0032-0781
Published online June 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm055
Xyloglucan Endo-transglycosylase (XET) Functions in Gelatinous Layers of Tension Wood Fibers in Poplar—A Glimpse into the Mechanism of the Balancing Act of Trees

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Tension wood is a specialized tissue of deciduous trees that functions in bending woody stems to optimize their position in space. Tension wood fibers that develop on one side of the stem have an increased potency to shrink compared with fibers on the opposite side, thus creating a bending moment. It is believed that the gelatinous (G) cell wall layer containing almost pure cellulose of tension wood fibers is pivotal to their shrinking. By analyzing saccharide composition and linkage in isolated G-layers of poplar, we found that they contain some matrix components in addition to cellulose, of which xyloglucan is the most abundant. Xyloglucan, xyloglucan endo-transglycosylase (XET) activity and xyloglucan endo-transglycosylase/hydrolase (XTH) gene products were detected in developing G-layers by labeling using CCRC-M1 monoclonal antibody, in situ incorporation of XXXG-SR and the polyclonal antibody to poplar PttXET16-34, respectively, indicating that xyloglucan is incorporated into the G-layer during its development. Moreover, several XTH transcripts were altered and were generally up-regulated in developing tension wood compared with normal wood. In mature G-fibers, XTH gene products were detected in the G-layers while the XET activity was evident in the adjacent S2 wall layer. We propose that XET activity is essential for G-fiber shrinking by repairing xyloglucan cross-links between G- and S2-layers and thus maintaining their contact. Surprisingly, XTH gene products and XET activity persisted in mature G-fibers for several years, suggesting that the enzyme functions after cell death repairing the cross-links as they are being broken during the shrinking process.

Keywords: Gravity responses; Populus; Reaction wood; Secondary wall; Wood formation; Xylogenesis

Journal Article.  7313 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.