The second most abundant biomass material on Earth- Xylan, has always presented a challenge when it comes to its extraction from plant cell walls. Its great potential as a source of stored solar energy for production of advance biofuels has stimulated researchers from the U.S. Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI) to look for overcoming the limitation.
The team identified a new gene in rice plants- dubbed XAX1. It suppression improves both the extraction of the material and the release of sugars needed for biofuel production. XAX1 was identified by the team as a biosynthetic protein specific to grass xylan synthesis, which can be modified to increase saccharification.
Henrik Scheller, head of JBEI’s Feedstocks Division and director of the Cell Wall Biosynthesis group notes that their findings can help increasing biofuel generation by understanding xylan synthesis and modifying xylan substitutions.
As a major component of plant cell walls, xylan, similarly to cellulose, serve as a source of nutrition to humans and animals. Still, there are very few enzymes that can synthesize xylan-type polysaccharides. According to Pamela Ronald, the corresponding author of the publication released in by the Proceedings of the National Academy of Sciences (PNAS), xylan can improve feedstocks for generation of biofuels. It inhibits access of enzymes that break down cellulose into sugars.
Using bioinformatics, the team of scientists identified the GT61 family of glycosyltransferases as being expanded in grasses and containing grass-specific subgroups. They found the mutant plant XAX1 by conducting a reverse genetics screen of 14 genes with highly expressed members of the GT61 family- insertional rice mutants. It is deficient in ferulic and aoumaric acid, which promote cross-linking between xylan chains and lignin.
Scheller is certain that this same principle can be applied to make rice plants more easily saccharified to bioenergy crops. It has the potential to be a powerful biotechnological tool for grass biofuel feedstock.