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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #126229
Title: INCORPORATION OF 5-HYDROXYCONIFERYL ALCOHOL INTO LIGNINS OF COMT-DEFICIENT POPLAR

Author
item Ralph, John
item MARITA, JANE - USDFRC
item LU, FACHUANG - UW MADISON
item LAPIERRE, CATHERINE - INRA-GRIGNON,FRANCE
item BOERJAN, WOUT - U. GENT, BELGIUM
item VAN DOORSSELAERE, JAN - U. GENT, BELGIUM
item PILATE, GILLES - INRA-ORLEANS, FRANCE
item JOUANIN, LISE - INRA-VERSAILLES, FRANCE

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/3/2001
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, a brown-midrib maize mutant (bm3), and in F5H-upregulated arabidopsis. In each case, 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 reliable proof 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 benzo-dioxanes. The endwise polymerization is therefore elegantly revealed, and is evidence that 5-hydroxyconiferyl alcohol should be recognized as an authentic lignin monomer in these angiosperms.