title: Ethanol yields and cell wall properties in divergently bred switchgrass genotypes.
abstract: Genetic modification of herbaceous plant cell walls to increase biofuels yields is a primary bioenergy research goal. Using two switchgrass populations developed by divergent breeding for ruminant digestibility, the contributions of several wall-related factors to ethanol yields was evaluated. Field grown low lignin plants significantly out yielded high lignin plants for conversion to ethanol by 39.1% and extraction of xylans by 12%. However, across all plants analyzed, greater than 50% of the variation in ethanol yields was attributable to changes in tissue and cell wall architecture, and responses of stem biomass to dilute-acid pretreatment. Although lignin levels were lower in the most efficiently converted genotypes, no apparent correlation were seen in the lignin monomer G/S ratios. Plants with higher ethanol yields were associated with an apparent decrease in the lignification of the cortical sclerenchyma, and a marked decrease in the granularity of the cell walls following dilute-acid pretreatment.
authors.affiliation: USDA Central-East Regional Biomass Center, Lincoln, NE 68583-0937, USA. Gautam.Sarath@ ars.usda.gov
authors.forename: Gautam
authors.initials: G
authors.lastname: Sarath
authors.forename: Bruce
authors.initials: B
authors.lastname: Dien
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Saathoff
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Vogel
authors.forename: Robert B
authors.initials: RB
authors.lastname: Mitchell
authors.forename: Han
authors.initials: H
authors.lastname: Chen
mesh_terms: D002473:Cell Wall / Q000737:chemistry*; D000431:Ethanol / Q000032:analysis*; D005838:Genotype; D006109:Poaceae / Q000235:genetics*
chemical_list: D000431:Ethanol