Cell-Wall Composition and Accessibility to Hydrolytic Enzymes is Differentially Altered in Divergently Bred Switchgrass (Panicum virgatum L.) Genotypes.
Authors:
Sarath, Gautam Mitchell, Robert B. Vogel, Kenneth P. USDA, ARS
Source:
Applied biochemistry and biotechnology. 2008 July, v. 150, no. 1, p. 1-14.
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.
