Making Trees More Bioenergy Friendly
Wood is a heterogeneous compound composed of the polysaccharides cellulose and hemicellulose, from which bioethanol can be derived, and the polymer lignin, which encloses the cellulosic material, provides rigidity and durability to the plant and makes it difficult to convert the cellulosic material to bioethanol. The content and composition of lignin varies by species of tree and by tissue and organ within a tree. A tree with reduced lignin content in the stems but with higher lignin in the roots would provide for more efficient and higher yielding ethanol production while at the same time enhancing carbon sequestration in the non-harvested below-ground tissues. Researchers at the DOE BioEnergy Research Center at Oak Ridge National Lab used pyrolysis molecular beam mass spectroscopy to characterize the lignin content in stems and roots from progeny of a three-generation pedigree of poplar, a tree species widely regarded as a potential biofuel crop. Several genetic regions associated with lignin content were identified that were root- and/or stem-specific, indicating the existence of gene(s) that differentially regulate lignin biosynthesis above and below ground. These results suggest that it may be possible to decrease stem lignin content through conventional or molecular breeding methods without impacting lignin in the roots.
Yin, T., X. Zhang, L. Gunter, R. Priya, R. Sykes, M. Davis, S.D. Wullschleger, and G.A. Tuskan. 2010. “Differential Detection of Genetic Loci Underlying Stem and Root Lignin Content in Populus,” PLoS ONE 5(11):e14021.