Transgenic down-regulation of caffeic acid O-methyltransferase (COMT) led to improved digestibility in tall fescue (Festuca arundinacea)

Chen, Lei; Auh, Chung-Kyoon; Dowling, Paul; Bell, J.; Lehmann, D.; Wang, Zeng‐Yu

doi:10.1071/fp03254

Cited by 108 publications

(67 citation statements)

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“…However, this enzyme showed only weak activity for CaAld and CA (4.6 and 2.9%, respectively). This specific activity spectrum is similar to those of several dicot CAldOMTs (Populus tremuloides CAldOMT, Li et al 2000; Arabidopsis thaliana CAldOMT, Nakatsubo et al 2008;and C. tinctorius CAldOMT, Nakatsubo et al 2007) and a grass CAOMT (TaCM) from T. aestivum (Ma and Xu 2008), but not another grass CAOMT (FaCOMT1b) from tall fescue (F. arundinacea, Chen et al 2004).…”

Section: Discussionmentioning

confidence: 70%

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Characterization of 5-Hydroxyconiferaldehyde O-Methyltransferase in Oryza sativa

Koshiba

Hirose

Mukai

et al. 2013

Plant Biotechnology

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Little is known regarding syringyl lignin biosynthesis in rice (Oryza sativa L. cv. Nipponbare). In the present study, the role of rice caffeic acid O-methyltransferase (OsCOMT1, Q6ZD89), was examined. The recombinant OsCOMT1 catalyzed the 5-Omethylation of 5-hydroxyferulate (5-HFA) and 5-hydroxyconiferaldehyde (5-HCAld). 5-HCAld inhibited 5-HFA methylation by this O-methyltransferase (OMT), while 5-HFA mitigated self-inhibition in 5-HCAld methylation. A rice plant in which OsCOMT1 expression was downregulated exhibited weakened cell wall staining with Wiesner reagent in vascular bundle cells and sclerenchyma tissue, compared with wild-type plants. The lignin content of transgenic rice plants was decreased and the syringyl lignin content reduced largely compared with that of the wild type. Taken together, these data indicated that OsCOMT1 functioned as a 5-HCAld OMT (OsCAldOMT1) in the biosynthetic pathway to syringyl lignin. Recently, because of the increased demand for biobased materials as alternatives to fossil carbon resources, gramineous plants that produce large amounts of inedible lignocellulosic biomass have been drawing attention as potential materials for biofuel and industrial feedstock production (Yamamura et al. 2013). Lignocellulose is composed mainly of lignin and polysaccharides. Lignin is a complex phenylpropanoid polymer, and fills the spaces between cell wall polysaccharides and confers mechanical strength and imperviousness to the cell wall (Boerjan et al. 2003). The inherent robust characteristics of lignin present obstacles to enzymatic hydrolysis of plant cell wall polysaccharides for biorefining, chemical pulping, and forage digestion. On the other hand, lignin is a promising raw material for aromatic feedstock production.Lignins are generally classified into three major groups: guaiacyl (4-hydroxy-3-methoxyphenyl), syringyl (3,5-dimethoxy-4-hydroxyphenyl), and p-hydroxyphenyl lignins. Lignin structures affect their reactivity and thermal properties. For example, plants with high syringyl lignin content are more easily delignified in kraft pulping than those with low syringyl lignin content (Chiang and Funaoka 1990;Lourenço et al. 2012;Shimizu et al. 2012). Condensed lignin structures reduce the thermal mobility of lignin (Kubo et al. 1997), indicating that syringyl lignin is beneficial for use in plastics, compared with guaiacyl lignin, because syringyl lignin lacks the condensed structures. Characterization of lignin and its biosynthetic mechanisms is a basis for the practical use of lignocelluloses.Syringyl lignin had long been proposed to be formed from p-coumaric acid (CouA) via caffeic acid (CA), ferulic acid (FA), 5-hydroxyferulic acid (5-HFA), sinapic acid (SA), sinapoyl CoA (SCoA), sinapaldehyde (SAld), and sinapyl alcohol (SAlc) (Figure 1), based on tracer experiments with isotope-labeled phenylpropanoid monomers and associated enzymatic experiments Original Paper DOI: 10.5511/plantbiotechnology.13.0219a Abbreviations: 4CL, 4-hydroxycinnamate CoA ligase; 5-HCAlc, 5-...

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Section: Discussionmentioning

confidence: 70%

“…Tall fescue (F. arundinacea) CAOMT (FaCOMT1b) showed the highest specific activity towards 5-HFA, followed by CaAld, CaAlc, and 5-HCAld. The enzyme's activities for CA and 5-HCAlc are very weak (Chen et al 2004). In comparison, perennial ryegrass (L. perenne) CAOMT (LpOMT1) showed ca.…”

Section: Discussionmentioning

confidence: 99%

Characterization of 5-Hydroxyconiferaldehyde O-Methyltransferase in Oryza sativa

Koshiba

Hirose

Mukai

et al. 2013

Plant Biotechnology

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“…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%

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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“…COMT down-regulation in switchgrass results in plants with normal growth and development (Fu et al, 2011a); the same is observed in perennial ryegrass (Tu et al, 2010) and tall fescue (Chen et al, 2004). The digestibility of switchgrass, perennial ryegrass and tall fescue biomass increased by 9%, 8.6% and 10.8% respectively compared to their respective controls.…”

Section: Caffeic Acid O-methyltransferasementioning

confidence: 54%

“…Alfalfa COMT can efficiently methylate caffealdehyde and caffeyl alcohol (Parvathi et al, 2001). COMT from tall fescue (Chen et al, 2004) and wheat (Ma & Xu, 2008) efficiently utilizes both caffealdehyde and 5-hydroxyconiferaldehyde. Further studies are needed to determine unequivocally the preferred routes for monolignol O-methylation in vivo.…”

Section: Caffeic Acid 3-o-methyltransferase (Comt)mentioning

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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Transgenic down-regulation of caffeic acid O-methyltransferase (COMT) led to improved digestibility in tall fescue (Festuca arundinacea)

Cited by 108 publications

References 0 publications

Characterization of 5-Hydroxyconiferaldehyde O-Methyltransferase in Oryza sativa

Characterization of 5-Hydroxyconiferaldehyde O-Methyltransferase in Oryza sativa

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

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

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