Sequencing around 5-Hydroxyconiferyl Alcohol-Derived Units in Caffeic Acid <i>O</i>-Methyltransferase-Deficient Poplar Lignins

Lu, Fachuang; Marita, Jane M.; Lapierre, Catherine; Jouanin, Lise; Morreel, Kris; Boerjan, Wout; Ralph, John

doi:10.1104/pp.110.154278

Cited by 57 publications

(44 citation statements)

References 27 publications

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“…The observation of benzodioxane substructure in COMT down-regulated switchgrass was consistent with previous reports that down-regulation of COMT during lignin biosynthesis resulted in the incorporation of 5-hydroxy coniferyl alcohol into lignin and generation of novel benzodioxane units Vanholme et al, 2010). For example, Lu et al (2010) reported that down-regulation of COMT in poplar led to the formation of benzodioxane units in lignin. Similarly, Vanholme et al (2010) observed the newly formed benzodioxane units in COMT down-regulated Arabidopsis.…”

Section: Hsqc Nmr Analysissupporting

confidence: 79%

“…For instance, COMT down-regulation of lignin in poplar has resulted in a decrease in lignin content, formation of benzodioxane, and a substantial decrease in syringyl units (Jouanin et al, 2000;Lu et al, 2010).…”

Section: Lignin Related Recalcitrance Reductionmentioning

confidence: 99%

“…Chen and Dixon (2007) reported that p-coumarate 3-hydroxylase (C3H) and hydroxycinnamoyl-CoA:shikimate/quinate hydroxycinnamoyl transferase (HCT) down-regulated alfalfa lines showed an improved fermentable sugar yield when compared to wild-type plants. The engineering of these enzyme genes is expected to generate a variation in lignin structures and thus impact the recalcitrance of biomass; therefore, there has been considerable interest in lignin structural characteristics in genetically engineered plants (Marita et al, 1999;Guo et al, 2001;Chen et al, 2004;Pu et al, 2009;Stewart et al, 2009;Lu et al, 2010;Tu et al, 2010;Vanholme et al, 2010;Ziebell et al, 2010). For example, Pu et al (2009) andZiebell et al (2010) isolated ball-milled lignin from C3H and HCT transgenic alfalfa lines and studied their structural features.…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass

Ragauskas

Samuel

et al. 2014

Front. Energy Res.

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This study examined the chemical structural characteristics of cellulolytic enzyme lignin isolated from switchgrass focusing on comparisons between wild-type control and caffeic acid 3-O-methyltransferase (COMT) down-regulated transgenic line. Nuclear magnetic resonance techniques including 13 C, 31 P, and two-dimensional 13 C-1 H heteronuclear single quantum coherence as well as gel permeation chromatography were employed. Compared to the wild-type, the COMT down-regulated transgenic switchgrass lignin demonstrated a decrease in syringyl (S):guaiacyl (G) ratio and p-coumarate:ferulate ratio, an increase in relative abundance of phenylcoumaran unit, and a comparable content of total free phenolic OH groups along with formation of benzodioxane unit. In addition, COMT down-regulation had no significant effects on the lignin molecular weights during its biosynthesis process.

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Section: Hsqc Nmr Analysissupporting

confidence: 79%

Section: Lignin Related Recalcitrance Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass

Ragauskas

Samuel

et al. 2014

Front. Energy Res.

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“…Ther esulting 5-hydroxyguaiacyl units react by typical 4-O-b-coupling with any of the hydroxycinnamyl alcohol monomers (the prototypical monolignols or further 5-hydroxyconiferyl alcohol), but the internal trapping of the intermediate quinone methide product by the novel 5-OH results in the formation of benzodioxane structures in the polymer. [11,92,[135][136][137][138][139] Benzodioxane levels can be amplified through acombination of F5H upregulation and COMT downregulation. In Arabidopsis,t he resulting plants may incorporate up to ca.…”

Section: Entry Speciesmentioning

confidence: 99%

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis

et al. 2016

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Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine‐tuning of multiple “upstream” (i.e., lignin bioengineering, lignin isolation and “early‐stage catalytic conversion of lignin”) and “downstream” (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a “beginning‐to‐end” analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.

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“…1.3A), Arabidopsis, aspen (Populus tremuloides), corn, perennial ryegrass, poplar (Populus tremula x alba), silver birch, Stylosanthes humilis, switchgrass, tall fescue and tobacco, COMT down-regulation causes a large reduction in S units, leading to lower S/G ratio and highlighting the involvement of COMT in S lignin biosynthesis. COMT down-regulation is usually accompanied by the appearance of 5-hydroxyguaiacyl units in lignin due to incorporation of 5-hydroxy-coniferyl alcohol with unique benzodioxane structures (Jouanin et al, 2000;Ralph et al, 2001aRalph et al, , 2001bMarita et al, 2003a;Morreel et al, 2004;Lu et al, 2010). An increase in biphenyl (5-5) and phenylcoumaran (β-5) lignin linkages has also been detected in COMT-deficient plants.…”

Section: Caffeic Acid O-methyltransferasementioning

confidence: 99%

Monolignol Biosynthesis and its Genetic Manipulation: The Good, the Bad, and the Ugly

Dixon

Reddy

Gallego‐Giraldo³

2014

Recent Advances in Polyphenol Research

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Economic and environmental factors favor the adoption of lignocellulosic bioenergy crops for production of liquid transportation fuels. However, lignocellulosic biomass is recalcitrant to saccharification (sugar release from cell walls), and this is, at least in part, due to the presence of the phenylpropanoid-derived cell wall polymer lignin. A large body of evidence exists documenting the impacts of lignin modification in plants. This technology can lead to improved forage quality and enhanced processing properties for trees (paper pulping) and lignocellulosic energy crops. We here provide a comprehensive review of the literature on lignin modification in plants. The pathway has been targeted through down-regulating expression of the enzymes of the monolignol pathway, as well as through down-regulation or over-expression of transcription factors that control lignin biosynthesis and/or programs of secondary cell wall development. Targeting lignin modification at some steps in the monolignol pathway can result in impairment of plant growth and development, often associated with the triggering of endogenous host defense mechanisms. Recent studies suggest that it may be possible to decouple negative growth impacts from lignin reduction.Keywords: monolignol biosynthesis, genetic modification, transcription factor, gene silencing, saccharification. 2 IntroductionLignin is a major component of plant secondary cell walls, and the second most abundant plant polymer on the planet. Lignin constitutes about 15-35% of the dry mass of vascular plants (Adler, 1977). Considerable attention has been given over the past several years to the reduction of lignin content in model plant species, forages, trees, and dedicated bioenergy feedstocks. This is because forage digestibility, paper pulping and liquid fuel production from biomass through fermentation are all affected by recalcitrance of lignocellulose, primarily due to the presence of lignin, which blocks accessibility of the sugar-rich cell wall polysaccharides cellulose and hemicellulose to enzymes and microorganisms (Pilate et al., 2002;Reddy et al., 2005;.Much is now known of the biosynthesis of lignin and its control at the transcriptional level. This information informs the targets that have been selected for genetic modification of lignin content and composition in transgenic plants. There is considerable variation in the effects on lignin content and composition depending on the gene that is targeted for down-or up-regulation. Equally important, lignin modification can have profound impacts on plant growth and development, ranging from good through bad to "downright ugly", but these impacts are again strongly target dependent. Understanding the mechanisms that may impact plant growth, which equate to agronomic performance, in crop species "improved" through lignin modification is critical for economic advancement of the forage and biofuels industries. Although still poorly understood, these mechanisms may also throw light on basal plant developmental and de...

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Sequencing around 5-Hydroxyconiferyl Alcohol-Derived Units in Caffeic Acid O-Methyltransferase-Deficient Poplar Lignins

Cited by 57 publications

References 27 publications

Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass

Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass

Paving the Way for Lignin Valorisation: Recent Advances in Bioengineering, Biorefining and Catalysis

Monolignol Biosynthesis and its Genetic Manipulation: The Good, the Bad, and the Ugly

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