Perturbation of wood cellulose synthesis causes pleiotropic effects in transgenic aspen

Chandrashekhar P. Joshi, Shivegowda Thammannagowda, Takeshi Fujino, Ji Qing Gou, Utku Avci, Candace H. Haigler, Lisa M. McDonnell, Shawn D. Mansfield, Bemnet Mengesha, Nicholas C. Carpita, Darby Harris, Seth Debolt, Gary F. Peter

Research output: Contribution to journalArticlepeer-review

72 Scopus citations

Abstract

Genetic manipulation of cellulose biosynthesis in trees may provide novel insights into the growth and development of trees. To explore this possibility, the overexpression of an aspen secondary wall-associated cellulose synthase (PtdCesA8) gene was attempted in transgenic aspen (Populus tremuloides L.) and unexpectedly resulted in silencing of the transgene as well as its endogenous counterparts. The main axis of the transgenic aspen plants quickly stopped growing, and weak branches adopted a weeping growth habit. Furthermore, transgenic plants initially developed smaller leaves and a less extensive root system. Secondary xylem (wood) of transgenic aspen plants contained as little as 10% cellulose normalized to dry weight compared to 41% cellulose typically found in normal aspen wood. This massive reduction in cellulose was accompanied by proportional increases in lignin (35%) and non-cellulosic polysaccharides (55%) compared to the 22% lignin and 36% non-cellulosic polysaccharides in control plants. The transgenic stems produced typical collapsed or 'irregular' xylem vessels that had altered secondary wall morphology and contained greatly reduced amounts of crystalline cellulose. These results demonstrate the fundamental role of secondary wall cellulose within the secondary xylem in maintaining the strength and structural integrity required to establish the vertical growth habit in trees.

Original languageEnglish
Pages (from-to)331-345
Number of pages15
JournalMolecular Plant
Volume4
Issue number2
DOIs
StatePublished - Mar 2011

Bibliographical note

Funding Information:
This work was partially supported by the National Science Foundation's CAREER program (IBN- 0236492), the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service program (# 2005-35103-15256) and the World Class University project of the Ministry of Science and Technology of Korea (R31-2009-000-20025-0) grants awarded to C.P.J. At North Carolina State University, C.H.H.’s research was supported by the Department of Crop Science and a grant from the Electron Microscopy Center, College of Agriculture and Life Science. The research work in the laboratory of S.D. was supported by the NSF-IOS 0922947 grant. No conflict of interest declared.

Keywords

  • Aspen
  • cell wall
  • cellulose synthesis
  • crystallinity
  • growth
  • irregular xylem
  • lignin
  • transgenic trees
  • xylem development

ASJC Scopus subject areas

  • Molecular Biology
  • Plant Science

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