07/29/2010
Alterations in Poplar Lignin Could Enhance Pretreatment Efficiency
Summary
Alterations in lignin content or structure in plant cell walls can have a profound effect on chemical or enzymatic degradability and the efficiency by which certain pretreatment methods remove lignin from polysaccharides. GLBRC researchers found that overexpression of a particular gene [ferulate 5-hydroxylase (F5H)] in the lignin biosynthetic pathway of a hybrid poplar created lignin with a structure and composition that can enhance lignin removal from cellulose, while still maintaining normal growth and development. When compared to wild-type poplar, the up-regulated F5H poplar has a much simpler lignin structure that is less branched and more homogeneous in its subunit composition, which makes the lignin easier to separate from cellulose during pretreatment. This and other poplar transgenic materials under investigation by GLBRC researchers have cell walls that release more sugar than wild-type poplar over a range of pretreatment methods. Ongoing work is examining the effect of ammonia fiber expansion pretreatment on these transgenic poplars.
References
Details on the lignin structure of F5H up-regulated poplar were reported in Stewart, J. J., et al. 2009. “The Effects on Lignin Structure of Overexpression of Ferulate 5-Hydroxylase in Hybrid Poplar,” Plant Physiology 150(2), 621-35.