New Target for Engineering Lignin for Biofuel Production
Plant cell walls contain polysaccharides that can be hydrolyzed into fermentable sugars, but this process is inhibited by lignin. Altering lignin composition or structure can reduce the amount of effort needed to release glucose from cellulose, thus improving the economics of cellulosic biofuels production. Department of Energy Great Lakes Bioenergy Research Center (GLBRC) researchers John Ralph and Hoon Kim and their colleagues at Ghent University and Flanders Institute of Biology have a goal of understanding the control points in the lignin biosynthetic pathway and how to use them to improve biomass properties. They identified a new target for engineering lignin for biofuel production by using transcriptomics and microarray studies to identify genes that co-express with other known lignin biosynthesis genes. In the model plant Arabidopsis, there are three cytochrome P450 reductase genes, and one of these three genes controls an enzyme (ATR2) that is co-expressed with lignin biosynthetic genes. By studying mutant plants in which the atr2 gene was down-regulated via T-DNA insertion, researchers found that the atr2 mutants had increased glucose release from cellulose relative to the wild type following base pretreatment. This increase in saccharification appeared to result from both altered lignin structure and altered lignin content. The results support the contention that ATR2 is involved in the lignin pathway and is thus a target for engineering plant cell walls that are better suited for biofuels applications. The study also suggests additional candidates in the lignin pathway for future study.
Sundin, L., R. Vanholme, J. Geerinck, G. Goeminne, R. Höfer, H. Kim, J. Ralph, and W. Boerjan. 2014. “Mutation of the Inducible ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE2 Alters Lignin Composition and Improves Saccharification,”Plant Physiology 166, 1956–71. DOI: 10.1104/pp.114.245548.