Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2003
Publication Date: November 4, 2003
Citation: Grabber, J.H. 2003. How do lignin composition, structure and cross-linking impact cell wall digestibility?. In: ASA-CSSA-SSSA Annual Meeting Abstracts, November 2-6, 2003, Denver, CO. 2003 CDROM. Technical Abstract: In a series of model studies, primary cell walls from Zea mays (L.) cell suspensions were synthetically lignified to assess whether variations in lignin composition, structure, and cross-linking influence cell wall degradation by fungal enzymes. Lignins formed with varying ratios of normal monolignols (p-coumaryl, coniferyl, and sinapyl alcohols) had similar impacts on cell wall hydrolysis; each unit of lignin reduced degradability by 2 units. Cell walls lignified with highly hydrophobic coniferaldehyde units were 30% less degradable than cell walls lignified with normal monolignols. In preliminary studies, acylation of monolignols p-coumarate did not alter cell wall degradability. Lignins formed by gradual 'end-wise' or rapid 'bulk' polymerization had markedly different structures but similar effects on cell wall degradability. Reductions in cell wall cross-linking, via oxidative coupling of feruloylated xylans to lignin or nucleophilic addition of structural polysaccharides to lignin quinone-methide intermediates, increased the initial hydrolysis of cell walls by up to 40% and the extent of hydrolysis by up to 25%. Overall, these studies suggest that reductions in lignin concentration, hydrophobicity, and cross-linking will improve the enzymatic hydrolysis and utilization of plant structural polysaccharides for nutritional and industrial purposes.