NMR characterization of altered lignins extracted from tobacco plants down-regulated for lignification enzymes cinnamylalcohol dehydrogenase and cinnamoyl-CoA reductase

Ralph, John; Hatfield, Ronald D.; Piquemal, Joël; Yahiaoui, Nabila; Péan, Michel; Lapierre, Catherine; Böudet, Alain M.

doi:10.1073/pnas.95.22.12803

Cited by 181 publications

(184 citation statements)

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“…Li et al (2001) have shown that the two substrate interactions (sinapaldehyde and coniferaldehyde) are of the competitive inhibition type for both PtCAD and PtSAD proteins. However, unlike in the pine CAD mutant and the bm1 maize and tobacco antisense lines (Halpin et al, 1998;Ralph et al, 1998), we did not observe any increase of coniferaldehyde incorporation in lignins of Atcad-D.…”

Section: Atcad-d Is Involved In Biosynthesis Of G or S Lignin Precursmentioning

confidence: 52%

“…Halpin et al (1994) obtained tobacco (Nicotiana tabacum) lines with low residual CAD activity as a consequence of downregulation of CAD. The xylem of these transgenic plants exhibits a red coloration, and their lignins incorporate cinnamyl-aldehydes (Ralph et al, 1998). Two-and 4-year-old CAD antisense transgenic poplars contain less lignins than control plants (Lapierre et al, 1999;Pilate et al, 2002) and show important modifications of their lignin composition (increase of free phenolic compounds and accumulation of sinapaldehyde).…”

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confidence: 99%

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Expression Pattern of Two Paralogs Encoding Cinnamyl Alcohol Dehydrogenases in Arabidopsis. Isolation and Characterization of the Corresponding Mutants

et al. 2003

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Studying Arabidopsis mutants of the phenylpropanoid pathway has unraveled several biosynthetic steps of monolignol synthesis. Most of the genes leading to monolignol synthesis have been characterized recently in this herbaceous plant, except those encoding cinnamyl alcohol dehydrogenase (CAD). We have used the complete sequencing of the Arabidopsis genome to highlight a new view of the complete CAD gene family. Among nine AtCAD genes, we have identified the two distinct paralogs AtCAD-C and AtCAD-D, which share 75% identity and are likely to be involved in lignin biosynthesis in other plants. Northern, semiquantitative restriction fragment-length polymorphism-reverse transcriptase-polymerase chain reaction and western analysis revealed that AtCAD-C and AtCAD-D mRNA and protein ratios were organ dependent. Promoter activities of both genes are high in fibers and in xylem bundles. However, AtCAD-C displayed a larger range of sites of expression than AtCAD-D. Arabidopsis null mutants (Atcad-D and Atcad-C) corresponding to both genes were isolated. CAD activities were drastically reduced in both mutants, with a higher impact on sinapyl alcohol dehydrogenase activity (6% and 38% of residual sinapyl alcohol dehydrogenase activities for Atcad-D and Atcad-C, respectively). Only Atcad-D showed a slight reduction in Klason lignin content and displayed modifications of lignin structure with a significant reduced proportion of conventional S lignin units in both stems and roots, together with the incorporation of sinapaldehyde structures ether linked at C␤. These results argue for a substantial role of AtCAD-D in lignification, and more specifically in the biosynthesis of sinapyl alcohol, the precursor of S lignin units.Lignin is a complex phenolic polymer whose structure is vital to functions such as imparting rigidity to plant organs and as a physical barrier to invading pests. Its presence in cell wall confers to vessels hydrophobic properties that facilitate conduction of water, photo-assimilates, and minerals to different parts of the plant. Lignin structure and composition differ widely at the interspecies level as well as cell types and at the subcellular cell wall level (Donaldson, 2001). Striking differences are mostly observable between gymnosperms and angiosperms. These taxa contain different qualitative and quantitative proportions of monolignols or cinnamyl alcohols representing the main lignin monomers. The formation of cinnamyl alcohols from the corresponding cinnamoylCoA esters requires two enzymatic modifications of the carbonate chain of the phenolic precursors. The first step is catalyzed by cinnamoyl CoA reductase, and the second step is catalyzed by cinnamyl alcohol dehydrogenase (CAD). CAD leads to the conversion of hydroxy-cinnamaldehydes to the corresponding alcohols. The relative proportions of these cinnamyl alcohols is an important factor for lignin structural traits and mechanical properties (Baucher et al., 1998;Mellerowicz et al., 2001).CAD was one of the first enzymes studied in the lignin syn...

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Section: Atcad-d Is Involved In Biosynthesis Of G or S Lignin Precursmentioning

confidence: 52%

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confidence: 99%

Expression Pattern of Two Paralogs Encoding Cinnamyl Alcohol Dehydrogenases in Arabidopsis. Isolation and Characterization of the Corresponding Mutants

et al. 2003

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“…It has been shown that lignin is difficult to chemically degrade and remove from plant cell walls, owing to its stable chemical linkages including ether and carbon–carbon bonds,5 as well as its accessibility to chemicals during industrial processing 6. However, researchers hypothesized that if chemically reactive bonds are introduced into the lignin polymer, lignin would be easier to degrade and extract under industrial conditions 7.…”

Section: Introductionmentioning

confidence: 99%

Chemical Pulping Advantages of Zip‐lignin Hybrid Poplar

et al. 2017

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Hybrid poplar genetically engineered to possess chemically labile ester linkages in its lignin backbone (zip‐lignin hybrid poplar) was examined to determine if the strategic lignin modifications would enhance chemical pulping efficiencies. Kraft pulping of zip‐lignin and wild‐type hybrid poplar was performed in lab‐scale reactors under conditions of varying severity by altering time, temperature and chemical charge. The resulting pulps were analyzed for yield, residual lignin content, and cellulose DP (degree of polymerization), as well as changes in carbohydrates and lignin structure. Statistical models of pulping were created, and the pulp bleaching and physical properties evaluated. Under identical cooking conditions, compared to wild‐type, the zip‐lignin hybrid poplar showed extended delignification, confirming the zip‐lignin effect. Additionally, yield and carbohydrate content of the ensuing pulps were slightly elevated, as was the cellulose DP for zip‐lignin poplar pulp, although differences in residual lignin between zip‐lignin and wild‐type poplar were not detected. Statistical prediction models facilitated comparisons between pulping conditions that resulted in identical delignification, with the zip‐lignin poplar needing milder cooking conditions and resulting in higher pulp yield (up to 1.41 % gain). Bleaching and physical properties were subsequently equivalent between the samples with slight chemical savings realized in the zip‐lignin samples due to the enhanced delignification.

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“…Recent reviews provide excellent coverage of the process and biochemistry of lignification (Baucher et al 1998, Boudet 1998. Lignin is deposited in the cell walls of plants as part of the process of cell maturation after cell elongation has ceased.…”

Section: Lignin Biochemistrymentioning

confidence: 99%

“…It is the last major biopolymer to have evolved within the plant kingdom and is generally regarded as the second most abundant compound, after cellulose, in the biosphere (Boudet 1998, Monties 1991. The most important function of lignin in plants is as a structural component to lend strength and rigidity to the cell wall.…”

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Lignin and fiber digestion

Moore¹,

Jung²

2001

REM

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Lignin is a polymer formed from monolignols derived from the phenylpropanoid pathway in vascular plants. It is deposited in the cell walls of plants as part of the process of cell maturation. Lignin is considered an anti-quality component in forages because of its negative impact on the nutritional availability of plant fiber. Lignin interferes with the digestion of cell-wall polysaccharides by acting as a physical barrier to microbial enzymes. Lignification therefore has a direct and often important impact on the digestible energy (DE) value of the forage. There are a number of plant-related factors that affect lignification in individual plants and plant communities. Lignification is under genetic control and there are considerable differences in lignin concentration and composition among species and even genotypes within species. Genetic differences in lignification are first expressed at the cellular level and are affected by biochemical and physiological activities of the cell. As cells differentiate, differences in lignification occur depending on the tissues and organs being developed. Lignification tends to be most intense in structural tissues such as xylem and sclerenchyma. Plant organs containing high concentrations of these tissues, such as stems, are less digestible than those containing lower concentrations. The relative proportion of lignified tissues and organs typically increases as plants mature so there is often a negative relationship between digestibility and maturity. All of these plant processes respond to environmental factors that can affect the extent and impact of lignification. Temperature, soil moisture, light, and soil fertility can have either direct or indirect effects on lignification. The most useful management practices for minimizing the negative effects of lignification are manipulation of the plant community such that it contains more desirable species and harvest management to maintain plants in a vegetative stage of development. Key Words: Anti-quality, digestibility, forage quality, forage utilizationLignin is considered an anti-quality component in forages because of its negative impact on the nutritional availability of plant fiber. It differs from most other classes of antiquality components in forages in that it is a structural compound rather than a secondary metabolite. Its evolution in plants is primarily related to plant structure and function and not as a defense mechanism against other organisms. As a component of the cell wall, lignin plays an important role in morphogenesis. Cell walls form the structural framework of the plant architecture that provides mechanical support for plant organs (Varner and Lin 1989). Cell walls also are involved in water balance, ion exchange, cell ResumenLa lignina es un polímero formado de monolignoles derivados de la vía fenilpropanoide de las plantas vasculares. Se deposita en las paredes celulares de las plantas como parte del proceso de maduración de la célula. En los forrajes, la lignina se considera como un compone...

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NMR characterization of altered lignins extracted from tobacco plants down-regulated for lignification enzymes cinnamylalcohol dehydrogenase and cinnamoyl-CoA reductase

Cited by 181 publications

References 46 publications

Expression Pattern of Two Paralogs Encoding Cinnamyl Alcohol Dehydrogenases in Arabidopsis. Isolation and Characterization of the Corresponding Mutants

Expression Pattern of Two Paralogs Encoding Cinnamyl Alcohol Dehydrogenases in Arabidopsis. Isolation and Characterization of the Corresponding Mutants

Chemical Pulping Advantages of Zip‐lignin Hybrid Poplar

Lignin and fiber digestion

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