Sugarcane is one of the most efficient photosynthesizer in the plant kingdom, able to convert as much as 2% of incident solar energy into biomass. A large amount of lignocellulosic biomass such as leaf litter residues and bagasse are generated during the sugarcane harvest or after the sugar refining process, respectively. Therefore, lignocellulosic biomass from leaf and processing residues will likely become a valuable feedstock for biofuel production. However, higher temperatures and/or acid concentrations result in dehydration of xylose to furfural, and glucose to hydroxymethyl furfural, which act as inhibitors of the fermentation process. New pretreatment protocols are being developed that require the application of xylanases and other enzymes for maximal yields of xylose. Our objectives target the improvement of fermentable sugar yields from hemicellulosic sugarcane residues and enhancing the biosafety of the transgenic plants. We evaluated two transgenic approaches: lignin modification by RNAi suppression of the lignin biosynthetic gene COMT and in planta production of a hyperthermostable xylanase. More than 200 transgenic sugarcane plants were generated and lines with suppression or expression of the target genes were selected. RNAi suppression of COMT resulted in reduced lignin content and altered lignin composition. In planta produced xylanase Xyl10B converted the majority of sugarcane xylan to fermentable xylobiose. Performance and conversion efficiency of transgenic plants grown in replicated field plots under USDA-Aphis notification 11-040-120 will also be presented.

The direct use of mutation is a valuable approach to generate variability in crops. The electron beam, one of the ionizing radiations, has been applied to evaluate its effect on seed germination and early seedling growth of creeping bentgrass (Agrostis palustris Huds., cv Penn-A1). The mature dry seeds were irradiated with various electron beam energies (0.3, 1.0, 1.3, and 2 MeV) and current levels (0.03 and 0.06 mA). Although large variability was existed within each dose, distinct difference of germiability and seedling vigor were not found at 0.3 MeV / 0.03 mA and 0.3 MeV / 0.06 mA beam condition. However, 1.0 MeV / 0.06 mA application most effectively inhibited and retarded seed germination and most severely restricted cotyledon and root growth in early seedling growth. The direct use of electron beam would be a valuable supplementary approach to generate mutants suitable for breeding purposes.