Corn stover is a substantial source of biomass.  It is estimated that up to 50 percent of stover or roughly 3.5 million tonnes could be harvested from Canadian corn fields and used as a feedstock for biofuels. The enzymatic cost for cellulose degradation is a major obstacle for the eventual commercialization of cellulosic ethanol. Cellulose is degraded through synergistic action of two general types of cellulase enzymes: those that cleave the cellulose chain internally (endo-1-4 β-D-glucanase) to provide new reducing and non-reducing chain termini on which exo-1-4 β-D-glucanases can operate to produce cellobiose. We report on progress to modify corn with cellulose degrading enzymes, sequestered in cell compartments, so as not to effect biomass production, but to be available for post-harvest cellulose degradation. We also report on the introduction of a sucrose isomerase to increase sugar production as a source of fermentable substrate for direct conversion to ethanol in silage corn (Canadian annual production - 4.5 million metric tonnes), or to enhance microbial fermentation of cellulosic biomass.