Making Better Feedstocks for Bioenergy by “Cracking” Switchgrass’s “Backbone”
The perennial grass switchgrass is considered one of the most promising biofuel feedstocks because of its high yield potential and ability to thrive on lands poorly suited for conventional agriculture. However, the presence of lignin within the cell walls, which provides rigidity and pathogen resistance to the plant, also confers resistance to breakdown into constituent sugars. This recalcitrance to cell wall deconstruction limits current efforts to convert these sugars into biofuels. Now researchers at the U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS), with funding from the joint USDA-DOE Plant Feedstock Genomics for Bioenergy Program, have re-engineered switchgrass to produce a modified lignin that, when subjected to alkaline pretreatment, released a modest but significant increase in glucose compared to control plants. These modified plants have a reduced function of the gene catalyzing the last step in the lignin biosynthetic pathway (cinnamyl-alcohol dehydrogenase, or CAD). These results demonstrate the promise of this approach in developing high-yielding switchgrass lines for biofuel production.
Saathoff, A. J., G. Sarath, E. K. Chow, B. S. Dien, and C. M. Tobias. 2011. “Downregulation of Cinnamyl-Alcohol Dehydrogenase in Switchgrass by RNA Silencing Results in Enhanced Glucose Release after Cellulase Treatment,” PLoS ONE 6(1): 16416.