Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Overcoming the recalcitrance of lignocellulosic biomass is a major challenge in biofuel research. Cell wall morphology, transcript changes, and chemical properties associated with the formation and function of tension wood (TW), a tissue with high sugar release potential, was studied. TW was induced by leaning Populus deltoides (clone WV94) at an angle of about 45º. Tissues were sampled from normal wood (NW), opposite wood (OW) (compressed side of stem) and TW (elongated side of stem) after 6 weeks induction. Scanning electron microscopy confirmed the presence of G-layer (gelatinous cell wall layer) in TW. Gel permeation chromatography (GPC) and 13C solid-state nuclear magnetic resonance (NMR) showed higher molecular weight and crystallinity of cellulose in TW than NW. Transcript analyses showed elevated levels of secondary cell wall cellulose synthesis genes in TW in comparison to NW and OW. TW had both increased amounts of cellulose and increased enzymatic sugar release. Klason and acetyl bromide (AcBr) analyses showed reduced lignin content in TW. Genes encoding monolignol biosynthesis pathway proteins were decreased in expression during TW formation while expression of genes encoding enzymes involved in synthesis of S-lignin units were not affected. Differential expression of pectin and hemicelluloses was observed by glycome profiling of TW via ELISA analysis using 150 glycan-directed monoclonal antibodies. Funding from DOE center grant DOE DE-FG02-09ER20097 and BioEnergy Science Center grant DE-PS02-06ER64304. The BioEnergy Science Center is a U.S. Department of Energy Bioenergy Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science.