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United States Department of Agriculture

Agricultural Research Service

Title: Ferulate Cross-Linking in Grasses: Chemistry, Impact on Degradability, Andgenetic Manipulation

Authors
item Jung, Hans Joachim
item Ralph, John
item Hatfield, Ronald
item Grabber, John
item Ni, Weiting

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 1997
Publication Date: N/A

Technical Abstract: Grass cell walls are cross linked by ferulic acid molecules. Ferulate esters of arabinoxylan are deposited in the primary cell wall of grasses. At the end of cell elongation and the beginning of secondary wall thickening in the developmental process, peroxidase and hydrogen peroxide act on the mono-ferulate esters to form di-ferulate structures that cross link arabinoxylan chains. This may be a crucial mechanism for the termination of cell elongation. The monolignol precursors of lignin react with the mono- and di-ferulate esters to form cross links between polysaccharide and lignin in the cell wall. The ferulates act as nucleation sites for the initial deposition of lignin in the cell wall. We have demonstrated the formation of such cross links in both maize tissue culture and in intact plants. The maize tissue culture system has also allowed manipulation of cross linking by reduction of ferulate ester deposition. These modified cell walls have been valuable in demonstrating that cross linking of arabinoxylan chains by di-ferulates reduces rate, but not extent, of cell wall degradability. And formation of cross links between polysaccharide and lignin have been shown to reduce extent of cell wall digestion. Selection for plants with high and low amounts of ferulate cross linking is being conducted in smooth bromegrass. Transposon mutagenesis has been used in maize to produce mutant plants with reduced ferulate ester deposition. Isolation of the responsible gene is now underway.

Last Modified: 11/28/2014
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