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Title: Strong RNAi-inhibition of 4CL expression alters lignification, saccharification potential and productivity of field-grown poplar

Abstract

RNAi-associated down-regulation of the Pt4CL1 gene family encoding 4-coumarate:coenzyme A ligase (4CL) has been proposed as a means for reducing lignin content in cell walls, and thereby improving feedstock quality for paper and bioethanol production. Using hybrid poplars (Populus) we employed RNAi gene suppression of 4CL to generate 14 transgenic events and compared them to a non-transgenic control. After a two-year field trial we characterized the consequences of 4CL down-regulation on wood biochemistry and tree productivity. Lignin reductions correlated well with 4CL RNA expression, with a sharp decrease in lignin observed for RNA expression levels below ~50%. Lignin reductions greater than ~10% of the control value were associated with reduced productivity, decreased wood S/G (syringyl/guaiacyl) lignin monomer ratios, and increased incorporation of H-monomers (p-hydroxyphenyl) into cell walls. Strongly affected transgenic events were also characterized by patches of brown, discolored wood with about twice the extractive (complex polyphenolic) content of controls. There was no support for the hypothesis that reduced lignin would increase saccharification potential. The data presented suggest that a threshold of lignin reduction exists, beyond which there are large changes in wood chemistry and plant metabolism that affect productivity and potential ethanol yield.

Authors:
 [1];  [1];  [2]
  1. ORNL
  2. Oregon State University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1005187
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plant Physiology; Journal Volume: 2007; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; BIOCHEMISTRY; CELL WALL; CHEMISTRY; ETHANOL; GENES; HYPOTHESIS; LIGASES; LIGNIN; METABOLISM; MONOMERS; PRODUCTION; PRODUCTIVITY; RNA; SACCHARIFICATION; TREES; WOOD

Citation Formats

Tuskan, Gerald A, Gunter, Lee E, and Strauss, S. Strong RNAi-inhibition of 4CL expression alters lignification, saccharification potential and productivity of field-grown poplar. United States: N. p., 2007. Web.
Tuskan, Gerald A, Gunter, Lee E, & Strauss, S. Strong RNAi-inhibition of 4CL expression alters lignification, saccharification potential and productivity of field-grown poplar. United States.
Tuskan, Gerald A, Gunter, Lee E, and Strauss, S. Mon . "Strong RNAi-inhibition of 4CL expression alters lignification, saccharification potential and productivity of field-grown poplar". United States. doi:.
@article{osti_1005187,
title = {Strong RNAi-inhibition of 4CL expression alters lignification, saccharification potential and productivity of field-grown poplar},
author = {Tuskan, Gerald A and Gunter, Lee E and Strauss, S},
abstractNote = {RNAi-associated down-regulation of the Pt4CL1 gene family encoding 4-coumarate:coenzyme A ligase (4CL) has been proposed as a means for reducing lignin content in cell walls, and thereby improving feedstock quality for paper and bioethanol production. Using hybrid poplars (Populus) we employed RNAi gene suppression of 4CL to generate 14 transgenic events and compared them to a non-transgenic control. After a two-year field trial we characterized the consequences of 4CL down-regulation on wood biochemistry and tree productivity. Lignin reductions correlated well with 4CL RNA expression, with a sharp decrease in lignin observed for RNA expression levels below ~50%. Lignin reductions greater than ~10% of the control value were associated with reduced productivity, decreased wood S/G (syringyl/guaiacyl) lignin monomer ratios, and increased incorporation of H-monomers (p-hydroxyphenyl) into cell walls. Strongly affected transgenic events were also characterized by patches of brown, discolored wood with about twice the extractive (complex polyphenolic) content of controls. There was no support for the hypothesis that reduced lignin would increase saccharification potential. The data presented suggest that a threshold of lignin reduction exists, beyond which there are large changes in wood chemistry and plant metabolism that affect productivity and potential ethanol yield.},
doi = {},
journal = {Plant Physiology},
number = 5,
volume = 2007,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}