|Helm, Richard - VIRGINIA TECH|
|Quideau, Stephane - UNIV OF WISCONSIN-MADISON|
Submitted to: Keystone Symposium on Extracellular Matrix of Plants: Molecular, Cellular A
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 1996
Publication Date: N/A
Technical Abstract: Ferulic acid in grasses is an important intermediary in cross-linking polysaccharides to lignin. Active incorporation of ferulates directly into the lignin polymer via oxidative coupling (radical) mechanisms has now been unequivocally demonstrated and predominates over the traditionally invoked 'passive' incorporation. Such incorporation produces a range of structures from which ferulate cannot be released and therefore cannot be quantitated by traditional solvolytic methods. Additionally, ferulate polysaccharide esters dimerize to produce a range of dehydrodiferulates. The total quantity of releasable dehydrodiferulates is up to 20-fold higher than determined previously, and can account for over half of the total ferulate in the cell wall. Dehydrodiferulates also actively incorporate into lignins providing a unique method of simultaneously cross-linking polysaccharides to each other and to lignins. Finally, ferulates and dehydrodiferulates function as initiation sites for wall lignification. Ferulates have been found to attach exclusively to lignin monomers (and not lignin oligomers or polymers) and are thus critical entities in directing lignification and cell wall cross-linking during plant growth and development. The cross- linking of polysaccharides to each other and to lignin also has a marked impact on the degradability of wall polysaccharides.