Modified Expression of Genes Significantly Reduces Recalcitrance of Lignocellulosic Biomass

ApplicationEngineeredplant species providing for higher efficiency of the biomas-to-biofuels process ProblemsAddressed    Biomass is a renewable resource that has shown promise toreplace petroleum based fuels, while reducing green house gas emissions. Theplant cell walls, which are the dominant component of feedstocks, containpolysaccharides such as cellulose, heteroxylans, and glucomannans that canultimately be con-verted to fuel. However, the production of biomass-basedfuels has not been cost competitive relative to oil or other energy resources.A key challenge is cell walls have built up a natural protection (orrecal-citrance) that makes the process of converting polysaccharides tofermentable sugars inefficient.TechnologySummaryResearchers at the University of Georgia havehas discovered a way to modify plant genes in order to improve the efficiencyof converting biomass into biofuels. The researchers have developed a methodfor identifying candidate plants that can be modified to be more amenable tothe conversion process. The present invention includes methods for altering theexpression of any of the coding regions encod-ing relevant polypeptides. Thisinvention seeks to improve the plant to fuel conversion by modifying the genesof plants to then make the saccharides easier to process. Specifically, theresearchers have shown that biofuel crops can be manipulated via genetictransformation or directed breeding to produce plants that have non-functionalcopies of a very important gene associated with certain tranferases. Theexpression of these genes in plants contributes to lignocellulosic recalcitraneto saccharification. Mutant plants engineered to have no functional copies ofone member of the gene family produce secondary side walls that containglucuronoylan with much reduced levels of 4-o-methyl-glucuronic acid and muchhigher levels of un-methylated gluronic acid. Furthermore, lignocellulosicmaterial from mutant stems show differences in resistance to enzyme catalyzedsaccharification when compared to lignocellulosic material prepared from thesteps of wild type plants. As result, biofuel plants lacking such genes or thathave reduced levels of their expression will provide improved lignocelluslosicfeedstock for the cost-effective production of liquid biofuels.Two different techniques were successfullyemployed to alter the expression of the corresponding coding region, supportingthe versatility of the technology, promoters and regulatory regions. Thesegeneral procedures can potentially be utilized across other extremophileorganisms.

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