Increase in 4-Coumaryl Alcohol Units during Lignification in Alfalfa (Medicago sativa) Alters the Extractability and Molecular Weight of Lignin

Angela Ziebell, Kristen Gracom, Rui Katahira, Fang Chen, Yunqiao Pu, Art Ragauskas, Richard A. Dixon, Mark Davis

Research output: Contribution to journalArticlepeer-review

102 Scopus Citations

Abstract

The lignin content of biomass can impact the ease and cost of biomass processing. Lignin reduction through breeding and genetic modification therefore has potential to reduce costs in biomass-processing industries (e.g. pulp and paper, forage, and lignocellulosic ethanol). We investigated compositional changes in two low-lignin alfalfa (Medicago sativa) lines with antisense down-regulation of p-coumarate 3-hydroxylase (C3H) or hydroxycinnamoyl-CoA: shikimate hydroxycin-namoyltransferase (HCT). We investigated whether the difference in reactivity during lignification of 4-coumaryl alcohol (H) monomers versus the naturally dominant sinapyl alcohol and coniferyl alcohol lignin monomers alters the lignin structure. Sequential base extraction readily reduced the H monomer content of the transgenic lines, leaving a residual lignin greatly enriched in H subunits; the extraction profile high-lighted the difference between the control and transgenic lines. Gel permeation chromatography of isolated ball-milled lignin indicated significant changes in the weight average molecular weight distribution of the control versus transgenic lines (CTR1a, 6000; C3H4a, 5500; C3H9a, 4000; and HCT30a, 4000).

Original languageAmerican English
Pages (from-to)38961-38968
Number of pages8
JournalJournal of Biological Chemistry
Volume285
Issue number50
DOIs
StatePublished - 2010

NREL Publication Number

  • NREL/JA-5100-48152

Keywords

  • biomass
  • lignin
  • processing cost reduction

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