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United States Department of Agriculture

Agricultural Research Service


item Ralph, John
item Lu, Fachuang
item Marita, Jane
item Hatfield, Ronald
item Lapierre, Catherine
item Ralph, Sally
item Chapple, Clint
item Vermerris, Wilfred
item Boerjan, Wout

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/11/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: COMT is the enzyme responsible for methylating 5-hydroxyconiferyl aldehyde, on the way to producing syringyl units. It is deficient in recently examined transgenic poplars downregulated by two different methods, in F5H-upregulated transgenic arabidopsis, and in a brown-midrib maize mutant (bm3). In all cases, 5-hydroxyconiferyl alcohol incorporated intimately into the lignin. Benzodioxane (4-O-beta/5-O-alpha) structures are produced and can be characterized by their beautiful NMR correlations, by their survival through DFRC-degradation, and their partial survival through thioacidolysis. The level of detail revealed by these methods provides evidence that the novel 5-hydroxyconiferyl alcohol monomer cross-couples with syringyl and guaiacyl units into the growing lignin oligomer, and that normal monolignols then add to the new 5-hydroxyguaiacyl terminus producing benzodioxanes. Demonstrated endwise polymerization into lignins suggests that 5-hydroxyconiferyl alcohol shoul be recognized as an authentic lignin monomer in these angiosperms.

Last Modified: 10/18/2017
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