America's dependence on foreign oil has severe economic, national security and environmental consequences. The development of alternative fuels and renewable energy can alleviate these problems. The USDA has established research on renewable energy as a high priority. Cellulosic ethanol from bioenergy crops like switchgrass has the potential to become an important component of America's effort to reduce its dependence on foreign oil. As an additional benefit, replacing fossil fuels with biofuels will lessen the buildup of greenhouse gases. To gain access to commercial markets, biofuels must become cost-competitive with fossil fuels. This will require improvements in refining technologies to efficiently convert cellulose to ethanol along with improvements in the agronomic productivity of biofuel crops, particularly under conditions of limiting nutrients and water. Roots play a critical role in the growth and development of all plants. In addition to providing anchorage, roots are the primary site of nutrient and water acquisition. To perform these tasks, the primary roots extend into soil and produce additional branching roots that originate from internal tissues. The network of the different types of roots on a single plant is known as its root system architecture. It is well established that plant root system architecture is correlated with agronomic productivity under limiting conditions. This goal of this proposal is to create enhanced biofuel crops by improving their root architecture in order to increase agronomic productivity under limiting conditions.
