REDESIGNING FORAGE GERMPLASM AND PRODUCTION SYSTEMS FOR EFFICIENCY, PROFIT, AND SUSTAINABILITY OF DAIRY FARMS
Location: Dairy Forage and Aquaculture Research
Title: USING DEHYDROGENATION POLYMER-CELL WALL COMPLEXES TO SCREEN POTENTIAL MONOLIGNOLS FOR ALTERING CELL WALL LIGNIFICATION AND UTILIZATION
Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 13, 2008
Publication Date: August 25, 2008
Citation: Grabber, J.H., Ralph, J., Schatz, P.F., Lu, F., Kim, H. 2008. Using dehydrogenation polymer-cell wall complexes to screen potential monolignols for altering cell wall lignification and utilization. Proceedings of Ferulate '08. p. 61.
Recent discoveries highlighting the metabolic malleability of plant lignification indicate that lignin can be engineered to dramatically alter its composition and properties. Current efforts are primarily aimed at manipulating the biosynthesis of normal monolignols, but in the future apoplastic targeting of phenolics from various metabolic pathways may provide new approaches for designing lignin that is less inhibitory toward polysaccharide fermentation or is easier to remove by biological or chemical treatments. To help identify promising new avenues for lignin bioengineering, we are artificially lignifying cell walls from maize cell suspensions with various combinations of normal monolignols (coniferyl and sinapyl alcohols) plus a variety of phenolics (hydroxycinnamate-monolignol esters, hydroxycinnamate-quinic acid esters, diferuloylated compounds, phenylpropanoids, phenolic glucosides, flavonoids, etc) synthesized in the laboratory. Our initial work demonstrated that copolymerzation of coniferyl ferulate with monolignols dramatically improved the alkaline extractability of lignin and the enzymatic hydrolysis of cell walls. In more recent studies, inclusion of feruloyl or caffeoyl quinic acids with monolignols considerably depressed lignin formation and strikingly improved cell wall fermentability by rumen microorganisms. In contrast, various catechin and phenylpropanoid units readily formed copolymer-lignins with normal monolignols; in some cases cell wall fermentability was positively related to the degree of catechin and phenylpropanoid hydroxylation. In addition to ruminal fermentability, we will characterize the extractability of lignin formed by these and other phenolics and the enzymatic saccharification of intact and chemically pretreated cell walls. Such work should facilitate the bioengineering of plant fiber for improved utilization by livestock and its conversion into ethanol, paper, and other industrial products.