Fourier-transform infrared and Raman spectroscopic evidence for the incorporation of cinnamaldehydes into the lignin of transgenic tobacco (Nicotiana tabacum L.) plants with reduced expression of cinnamyl alcohol dehydrogenase

• Published in: Planta Vol. 201; no. 3; pp. 311 - 318
• Main Authors: Stewart, D, Yahiaoui, N, McDougall, G.J, Myton, K, Marque, C, Boudet, A.M, Haigh, J. (Scottish Crop Research Inst., Dundee (United Kingdom). Dept. of Cellular and Environmental Physiology, Unit for Industrial Crops)
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01.03.1997; Springer; Springer Nature B.V
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ADN; ALCOHOL DEHYDROGENASE; ALCOHOL DESHIDROGENASA; Alcohols; ALCOOL DESHYDROGENASE; Antisense DNA; Biological and medical sciences; Biotechnology; Carbon; Carbonyl compounds; Carbonyl groups; Carbonyls; CELL WALLS; Cinnamaldehyd; Cinnamaldehyde; Cinnamylalkoholdehydrogenase; COMPOSE PHENOLIQUE; COMPUESTOS FENOLICOS; Crosslinking; Dehydrogenase; Dehydrogenases; DNA; ENZIMAS; ENZYME; ENZYMES; ENZYMIC ACTIVITY; ESPECTROMETRIA; EXPRESION GENICA; EXPRESSION DES GENES; Faerbung; Flowers & plants; Fourier transforms; Fundamental and applied biological sciences. Psychology; GENE EXPRESSION; Genetic engineering; Genetic technics; Guaiacyl; INFRARED RADIATION; Infrared spectroscopy; Infrared spectrum; Lignin; LIGNINAS; LIGNINE; LIGNINS; METABOLISM; Metabolism. Physicochemical requirements; METABOLISME; METABOLISMO; Methods. Procedures. Technologies; MODELE; MODELOS; NICOTIANA TABACUM; PARED CELULAR; PAROI CELLULAIRE; PHENOLIC COMPOUNDS; Plant physiology and development; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants; RADIACION INFRARROJA; Raman scattering; Raman spectra; Raman spectroscopy; RAYONNEMENT INFRAROUGE; Spectral reflectance; SPECTROMETRIE; SPECTROMETRY; Spectroscopic analysis; Spektroskopie; Stoffwechsel; Tobacco; Transgenic animals and transgenic plants; TRANSGENIC PLANTS; XILEMA; XYLEM; XYLEME; Lignin; Cinnamyl-alcohol dehydrogenase; Fourier transformation; Enzyme; Nicotiana tabacum; Cell wall; Infrared spectrometry; Dicotyledones; Angiospermae; Spermatophyta; Transgenic plant; Raman spectrometry; Oxidoreductases; Solanaceae; Antisense DNA; Biological accumulation
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250050072

Xylem from stems of genetically manipulated tobacco plants which had had cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) activity down-regulated to a greater or lesser degree (clones 37 and 49, respectively) by the insertion of antisense CAD cDNA had similar, or slightly higher, lignin contents than xylem from wild-type plants. Fourier-transform infrared (FT-IR) microspectroscopy indicated that down-regulation of CAD had resulted in the incorporation of moieties with conjugated carbonyl groups into lignin and that the overall extent of cross-linking, particularly of guaiacyl (4-hydroxy-3-methoxyphenyl) rings, in the lignin had altered. The FT-Raman spectra of manipulated xylem exhibited maxima consistent with the presence of elevated levels of aldehydic groups conjugated to a carbon-carbon double bond and a guaiacyl ring. These maxima were particularly intense in the spectra of xylem from clone 37, the xylem of which exhibits a uniform red coloration, and their absolute frequencies matched those of coniferaldehyde. Furthermore, xylem from clone 37 was found to have a higher content of carbonyl groups than that of clone 49 or the wild-type (clone 37: clone 49: wild-type; 2.4:1.6:1.0) as measured by a degradative chemical method. This is the first report of the combined use of FT-IR and FT-Raman spectroscopies to study lignin structure in situ. These analyses provide strong evidence for the incorporation of cinnamaldehyde groups into the lignin of transgenic plants with down-regulated CAD expression. In addition, these non-destructive analyses also suggest that the plants transformed with antisense CAD, in particular clone 37, may contain lignin that is less condensed (cross-linked) than that of the wild-type.