Genetic Engineering of Poplar Trees for the Biorefinery

Climate change and the depletion of fossil resources have urged the transition from a fossil-based to a bio-based society. In the bio-economy, lignocellulosic plant biomass can be converted to fermentable sugars. However, for the production of fermentable sugars from biomass, lignin, an aromatic heteropolymer, needs to be extracted from the biomass by costly pretreatments. Engineering of the amount and structure of lignin is an attractive strategy to improve the efficiency of biomass processing. Hence, significant research efforts have been devoted to unravel the lignin biosynthesis pathway and to investigate the effects of altering the expression of individual steps of this pathway on lignin amount and composition, and on biomass properties.

These studies have shown that lignin amount and composition can be altered and that biomass processing can be improved. We use Arabidopsis thaliana as a model to discover new genes of the lignin biosynthesis pathway. Genes that provide promising improvements in biomass processing upon their altered expression in this model system are then taken further for translational research in poplar and maize. Field trials have been established with GM poplar with modified lignin. These trials, established for a period of 8 years, show that field trials are an essential step in the translation of research towards applications.