title: Cell-wall composition and accessibility to hydrolytic enzymes is differentially altered in divergently bred switchgrass (Panicum virgatum L.) genotypes.
abstract: The aims of this study were to understand the genotypic variability in cell-wall composition and cell-wall accessibility to enzymes in select switchgrass plants obtained from two different populations derived from a base population of octaploid cultivars. Population C+3 was developed by three breeding generations for high digestibility and population C-1 developed by one generation of breeding for low digestibility. Above-ground biomass from 12 selected genotypes, three each with high or low digestibility within each population, was analyzed for their cell-wall aromatics and polysaccharides. The ratio of p-coumaric acid/ferulic acid was greater (P < or = 0.05) for the high-lignin C-1 population over the low-lignin C+3 population, although the amounts of these two phenolics did not differ between populations. Combined values of guaiacyl + syringyl-lignin were consistently higher in genotypes from the C-1 population as compared to the genotypes from the C+3 population. Overall, p-coumaric acid was released by enzymes in greater amounts than ferulic acid in all these genotypes. Genotypes in the C-1 population exhibited lower dry weight loss as compared to the genotypes in the C+3 population after enzymatic digestion, suggesting changes in cell-wall architecture. Overall, our data highlight the phenotypic plasticity coded by the switchgrass genome and suggest that combining dry matter digestibility with other more specific cell-wall traits could result in genotypes with greater utility as bioenergy feedstocks.
authors.affiliation: Grain, Forage, and Bioenergy Research Unit, Department of Agronomy and Horticulture, U.S. Department of Agriculture-Agricultural Research Service, East Campus, Lincoln, NE 68583-0737, USA. gautam.sarath@ars.usda.gov
authors.forename: Gautam
authors.initials: G
authors.lastname: Sarath
authors.forename: Danny E
authors.initials: DE
authors.lastname: Akin
authors.forename: Robert B
authors.initials: RB
authors.lastname: Mitchell
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Vogel
mesh_terms: D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D004063:Digestion; D014644:Genetic Variation; D005838:Genotype; D006868:Hydrolysis; D008897:Panicum / Q000145:classification / Q000201:enzymology*