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

Homologous antisense constructs were used to down-regulate tobacco cinnamyl-alcohol dehydrogenase (CAD; EC 1.1.1.195) and cinnamoyl-CoA reductase (CCR; EC 1.2.1.44) activities in the lignin monomer biosynthetic pathway. CCR converts activated cinnamic acids (hydroxycinnamoyl-SCoAs) to cinnamaldehyde...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1998-10, Vol.95 (22), p.12803-12808
Main Authors: Ralph, J. (United States Dairy Forage Research Center, USDA-ARS, Madison, WI.), Hatfield, R.D, Piquemal, J, Yahiaoui, N, Pean, M, Lapierre, C, Boudet, A.M
Format: Article
Language:English
Subjects:
ADN
ALCOHOL DEHYDROGENASE
ALCOHOL DESHIDROGENASA
ALCOHOL OXIDOREDUCTASES
Alcohols
ALCOOL DESHYDROGENASE
ALDEHYDE OXIDOREDUCTASES
Aldehydes
Amides
ANTISENSE DNA
AROMATIC COMPOUNDS
BIOSINTESIS
BIOSYNTHESE
BIOSYNTHESIS
CHEMICAL COMPOSITION
COMPOSE AROMATIQUE
COMPOSE PHENOLIQUE
COMPOSICION QUIMICA
COMPOSITION CHIMIQUE
COMPUESTOS AROMATICOS
COMPUESTOS FENOLICOS
DNA
Enzymes
ESPECTROSCOPIA RMN
Lignin
LIGNINAS
LIGNINE
LIGNINS
Monomers
NICOTIANA TABACUM
NMR SPECTROSCOPY
OXIDOREDUCTASES
OXIDORREDUCTASAS
OXYDOREDUCTASE
PHENOLIC COMPOUNDS
PLANTAS TRANSGENICAS
PLANTE TRANSGENIQUE
Plants
Polymers
Protons
SPECTROSCOPIE RMN
TRANSGENIC PLANTS
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Summary:Homologous antisense constructs were used to down-regulate tobacco cinnamyl-alcohol dehydrogenase (CAD; EC 1.1.1.195) and cinnamoyl-CoA reductase (CCR; EC 1.2.1.44) activities in the lignin monomer biosynthetic pathway. CCR converts activated cinnamic acids (hydroxycinnamoyl-SCoAs) to cinnamaldehydes; cinnamaldehydes are then reduced to cinnamyl alcohols by CAD. The transformations caused the incorporation of nontraditional components into the extractable tobacco lignins, as evidenced by NMR. Isolated lignin of antisense-CAD tobacco contained fewer coniferyl and sinapyl alcohol-derived units that were compensated for by elevated levels of benzaldehydes and cinnamaldehydes. Products from radical coupling of cinnamaldehydes, particularly sinapaldehyde, which were barely discernible in normal tobacco, were major components of the antisense-CAD tobacco lignin. Lignin content was reduced in antisense-CCR tobacco, which displayed a markedly reduced vigor. That lignin contained fewer coniferyl alcohol-derived units and significant levels of tyramine ferulate. Tyramine ferulate is a sink for the anticipated build-up of feruloyl-SCoA, and may be up-regulated in response to a deficit of coniferyl alcohol. Although it is not yet clear whether the modified lignins are true structural components of the cell wall, the findings provide further indications of the metabolic plasticity of plant lignification. An ability to produce lignin from alternative monoliters would open new avenues for manipulation of lignin by genetic biotechnologies
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.95.22.12803