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Abstract Detail


Cell Walls

Al-Haddad, Jameel [1], Koehler, Lothar [2], Mansfield, Shawn [3], Ewers, Frank, W [4], Telewski, Frank W. [5].

Influence of genetically modified lignin composition on cell wall chemistry, mechanics, and plant water relations in hybrid poplars (Populus tremula x P. alba).

Poplar wood is among the targeted species by paper and pulp industries. Attempts have been successful in improving poplar (Populus tremula x alba) wood lignin extractability by increasing syringyl (S) to guaiacyl (G) monomer ratio in F5H overexpression clones. Questions on whether the modified wood’s cell wall chemistry, mechanics, and water relations have been changed were addressed in this study. One m high wild type and overexpression clones were propagated from root sprouts in the greenhouse. Three types of xylem tissues; normal, opposite, and tension wood were analyzed in upright or artificially inclined trees with 45° angle from vertical. Tension wood was marked by significantly lower percent total lignin and decreased microfibril angle. Due to the formation of the G-layer, cellulose crystallinity in tension wood increased compared to normal or opposite wood. Interestingly, percent sugars in tension wood decreased with increased S/G ratio. As was previously reported, percent acid soluble lignin significantly increased with increasing syringyl content. Mechanical testing showed that inclining the trees increases flexural rigidity of the wood compared to the controls with no significant change in the modulus of elasticity. Although no change was observed in the inclined and upright trees’ vulnerability to embolism, increased specific water conductivity was a characteristic of normal wood in response to increased syringyl content. Evaluating the response of these F5H overexpression clones to inclination will improve our understanding of the role lignin monomer composition plays in xylem chemical anatomy and mechanical and physiological properties of normal and tension wood.


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1 - Michigan State University, Plant Biology, 166 Plant Biology Building, East Lansing, Michigan, 48824, USA
2 - Michigan State University, Plant Biology, 166 Plant Biology Building, East Lansing, MI, 48824, USA
3 - University of British Columbia, Department of Wood Science, Vancouver, BC, Canada
4 - Biological Sciences Department, California State Polytechnic University, Pomona, CA, USA
5 - Michigan State University, Department of Plant Biology, W.J. Beal Botanical Garden, 166 Plant Biology Laboratory, East Lansing, MI, 48824, USA

Keywords:
lignin
poplar
syringyl
guaiacyl
Tension wood
cell wall
Populus tremula x alba
Cellulose
crystallinity
biomechanics
Water relations
microfibril angle
F5H.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P17041
Abstract ID:2095


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