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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #213453
Title: MOLECULAR PHENOTYPING OF LIGNIN-MODIFIED TOBACCO REVEALS ASSOCIATED CHANGES IN CELL WALL METABOLISM, PRIMARY METABOLISM, STRESS METABOLISM AND PHOTORESPIRATION

Author
item DAUWE, REBECCA - GENT UNIV, BELGIUM
item MORREEL, KRIS - GENT UNIV, BELGIUM
item GOEMINNE, GEERT - GENT UNIV, BELGIUM
item GIELEN, BIRGIT - GENT UNIV, BELGIUM
item ROHDE, ANTJE - GENT UNIV, BELGIUM
item VAN BEEUMEN, JOS - GENT UNIV, BELGIUM
item Ralph, John
item BOUDET, ALAIN-M - UMR, FRANCE
item ROCHANGE, SOIZIC - UMR, FRANCE
item KOPKA, JOACHIM - MPI, GERMANY
item HALPIN, CLAIRE - UNIV OF DUNDEE, SCOTLAND
item MESSENS, ERIC - GENT UNIV, BELGIUM
item BOERJAN, WOUT - GENT UNIV, BELGIUM

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2007
Publication Date: 8/28/2007
Citation: Dauwe, R., Morreel, K., Goeminne, G., Gielen, B., Rohde, A., Van Beeumen, J., Ralph, J., Boudet, A., Rochange, S., Kopka, J., Halpin, C., Messens, E., Boerjan, W. 2007. Molecular phenotyping of lignin-modified tobacco reveals associated changes in cell wall metabolism, primary metabolism, stress metabolism and photorespiration. Plant Journal. 52:263-285.

Interpretive Summary: Lignin is a polymer that is mainly present in plant cell walls, where it provides strength, defense, and allows for water transport through the plant. There is wide interest in understanding the process of lignin biosynthesis and deposition because of its economic relevance. Plant varieties with altered lignin content and composition can have improved performance as fodder crops or in the production of paper and pulp. However, in studies to date, the effects on the plant of perturbing single genes in the lignin biosynthetic pathway have been only examined in a relatively simplistic way. The pathways impacted by that gene have been examined and the effect, for example, on the structure of lignin, has been elucidated. But how the whole biochemistry of the plant responds has not been examined in a holistic manner. Collaborators in Belgium and elsewhere used sophisticated approaches to determine the effects of perturbing two key lignin genes on various aspects of plant metabolism. As noted in the title, the gene-perturbations caused various effects on general plant metabolism and photorespiration (see Wikipedia). Such studies begin to allow scientists to understand how various biochemical processes in the plant interact, and provide the foundations for improving the utilization of our crop and forest plant resources.

Technical Abstract: Lignin is an important component of secondary thickened cell walls. Cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) are two key enzymes catalyzing the penultimate and last step in the biosynthesis of the monolignols. Down-regulation of CCR in tobacco has been shown to reduce lignin content, whereas lignin in tobacco down-regulated for CAD incorporates more aldehydes. Here, we show that altering the expression of either or both genes in tobacco has far-reaching consequences on the transcriptome and metabolome. A cDNA-AFLP-based survey of 11,000 transcript-derived fragments revealed differential transcripts of genes within the monolignol biosynthetic pathway, but also of genes in a number of other metabolic pathways. HPLC and GC-MS-based metabolite profiling largely supported the transcript data. In general, the differential transcript and metabolite profiles pointed toward a decreased biosynthesis of starch and cell wall matrix polysaccharides, a general stress response and photo-oxidative stress, and an increased photorespiration, mainly in the CCR-deficient plants. The predicted effects on the photosynthetic apparatus were subsequently confirmed physiologically by fluorescence and gas-exchange measurements.