The Effects on Lignin Structure of Overexpression of Ferulate 5-Hydroxylase in Hybrid Poplar1

Stewart, Jaclyn J.; Akiyama, Takuya; Chapple, Clint; Ralph, John; Mansfield, Shawn D.

doi:10.1104/pp.109.137059

Cited by 370 publications

(312 citation statements)

References 43 publications

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“…Previously, even heptamers and octamers have been observed in oligolignol profiles of poplar xylem (G. Goeminne, K. Morreel, and W. Boerjan, unpublished data); such oligomers appear to be close to the estimated average polymer length of extremely S-rich lignins (i.e. approximately 10 units; Stewart et al, 2009). However, the longer an oligolignol, the more isomers exist, in minute individual amounts, that cannot be fully resolved by reverse-phase LC.…”

Section: Discussionmentioning

confidence: 99%

Mass Spectrometry-Based Sequencing of Lignin Oligomers

Morreel

Dima²,

Kim³

et al. 2010

Plant Physiol.

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171

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Although the primary structure of proteins, nucleic acids, and carbohydrates can be readily determined, no sequencing method has been described yet for the second most abundant biopolymer on earth (i.e. lignin). Within secondary-thickened plant cell walls, lignin forms an aromatic mesh arising from the combinatorial radical-radical coupling of monolignols and many other less abundant monomers. This polymerization process leads to a plethora of units and linkage types that affect the physicochemical characteristics of the cell wall. Current methods to analyze the lignin structure focus only on the frequency of the major monomeric units and interunit linkage types but do not provide information on the presence of less abundant unknown units and linkage types, nor on how linkages affect the formation of neighboring linkages. Such information can only be obtained using a sequencing approach. Here, we describe, to our knowledge for the first time, a sequencing strategy for lignin oligomers using mass spectrometry. This strategy was then evaluated on the oligomers extracted from wild-type poplar (Populus tremula 3 Populus tremuloides) xylem. In total, 134 lignin trimers to hexamers were observed, of which 36 could be completely sequenced. Interestingly, based on molecular mass data of the unknown monomeric and dimeric substructures, at least 10 unknown monomeric units or interunit linkage types were observed, one of which was identified as an arylglycerol end unit.Lignin is an aromatic heteropolymer that is mainly present in secondary-thickened plant cell walls, allowing the transport of water and nutrients and providing the necessary strength for the plant to grow upwardly Vanholme et al., 2008Vanholme et al., , 2010. In angiosperms, lignin is predominantly composed of guaiacyl (G) and syringyl (S) units that are derived from combinatorial radical-radical coupling of the monolignols coniferyl and sinapyl alcohol, respectively Fig. 1A). Following oxidation of the monolignols by peroxidase and/or laccase, the resulting electron-delocalized radical has unpaired electron density at its 1-, 3-, O-4-, 5-, and 8-positions (Fig. 1B); note that much of the lignin literature uses Greek letters for the side chain, a, b, and g for the 7-, 8-, and 9-positions. As radical coupling at the 8-position is favored, coupling with another monolignol radical affords, after rearomatization, a mixture of dehydrodimers with 8-8-, 8-5-, and 8-O-4-linkages (Fig. 1C). Following dimerization, polymerization will continue by the coupling of the 8-position of an incoming monolignol radical to the O-4-position of the dimer's phenolic end. In the case of a G dimer, coupling can also occur, albeit at a lower frequency, to the 5-position. Thus, chain elongation creates 8-5-and 8-O-4-linkages (Adler, 1977). Besides the monolignols and other monomers that are present in minor amounts , the plasticity of lignin polymerization permits the incorporation of any phenolic that enters the lignification site, subject to its chemical cross-coupling propensit...

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Section: Discussionmentioning

confidence: 99%

Mass Spectrometry-Based Sequencing of Lignin Oligomers

Morreel

Dima²,

Kim³

et al. 2010

Plant Physiol.

Self Cite

171

213

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“…and Arabidopsis (Arabidopsis thaliana; Bonawitz and Chapple, 2010). Increasing expression of the poplar ferulate-5-hydroxylase gene results in lignin that is almost entirely syringyl (S) lignin (Stewart et al, 2009) and substantially enhances kraft pulping efficiency in poplar (Huntley et al, 2003) and increases the effectiveness of a liquid hot water treatment to improve Glc yield via enzymatic digestion (Li et al, 2010b). Improvements in processing efficiencies are also observed by exploiting the natural variation in lignin composition in poplar.…”

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confidence: 91%

Genetic Determinants for Enzymatic Digestion of Lignocellulosic Biomass Are Independent of Those for Lignin Abundance in a Maize Recombinant Inbred Population

et al. 2014

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Biotechnological approaches to reduce or modify lignin in biomass crops are predicated on the assumption that it is the principal determinant of the recalcitrance of biomass to enzymatic digestion for biofuels production. We defined quantitative trait loci (QTL) in the Intermated B73 3 Mo17 recombinant inbred maize (Zea mays) population using pyrolysis molecular-beam mass spectrometry to establish stem lignin content and an enzymatic hydrolysis assay to measure glucose and xylose yield. Among five multiyear QTL for lignin abundance, two for 4-vinylphenol abundance, and four for glucose and/or xylose yield, not a single QTL for aromatic abundance and sugar yield was shared. A genome-wide association study for lignin abundance and sugar yield of the 282-member maize association panel provided candidate genes in the 11 QTL of the B73 and Mo17 parents but showed that many other alleles impacting these traits exist among this broader pool of maize genetic diversity. B73 and Mo17 genotypes exhibited large differences in gene expression in developing stem tissues independent of allelic variation. Combining these complementary genetic approaches provides a narrowed list of candidate genes. A cluster of SCARECROW-LIKE9 and SCARECROW-LIKE14 transcription factor genes provides exceptionally strong candidate genes emerging from the genome-wide association study. In addition to these and genes associated with cell wall metabolism, candidates include several other transcription factors associated with vascularization and fiber formation and components of cellular signaling pathways. These results provide new insights and strategies beyond the modification of lignin to enhance yields of biofuels from genetically modified biomass.

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“…Several low molecular mass cross-coupling products γ-acylated with p-hydroxybenzoate were isolated from actively lignifying poplar xylem [29,32]. Enhanced interest in p-hydroxybenzoates has surfaced in conjunction with reduced lignification in aspen and poplar following down-or upregulation of genes in the monolignol pathway [38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Naturally p-Hydroxybenzoylated Lignins in Palms

et al. 2015

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The industrial production of palm oil concurrently generates a substantial amount of empty fruit bunch (EFB) fibers that could be used as a feedstock in a lignocellulosebased biorefinery. Lignin byproducts generated by this process may offer opportunities for the isolation of value-added products, such as p-hydroxybenzoate (pBz), to help offset operating costs. Analysis of the EFB lignin by nuclear magnetic resonance (NMR) spectroscopy clearly revealed the presence of bound acetate and pBz, with saponification revealing that 1.1 wt% of the EFB was pBz; with a lignin content of 22.7 %, 4.8 % of the lignin is pBz that can be obtained as a pure component for use as a chemical feedstock. Analysis of EFB lignin by NMR and derivatization followed by reductive cleavage (DFRC) showed that pBz selectively

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The Effects on Lignin Structure of Overexpression of Ferulate 5-Hydroxylase in Hybrid Poplar1

Cited by 370 publications

References 43 publications

Mass Spectrometry-Based Sequencing of Lignin Oligomers

Mass Spectrometry-Based Sequencing of Lignin Oligomers

Genetic Determinants for Enzymatic Digestion of Lignocellulosic Biomass Are Independent of Those for Lignin Abundance in a Maize Recombinant Inbred Population

Naturally p-Hydroxybenzoylated Lignins in Palms

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