Inorganic nitrogen is a vital nutrient for plants. Soil nitrate provides as much as 90 percent of the nitrogen taken up by most plants and leads to a dramatic change in gene expression, which is critical to direct the productivity and survival of the plant. Consequently, nitrate is commonly provided by way of fertilizer to improve crop yield. However, many crop plants are inefficient in their ability to utilize the nitrogen. For example, corn and wheat typically only utilize 50 percent of the nitrogen applied to the soil and paddy rice may recoup as little as 30 percent. Nitrogen not used by crops may contribute to severe environmental problems, including pollution of ground water, run-off into nearby bodies of water, and release of greenhouse gases into the atmosphere. Plants take up and assimilate nitrate in response to its availability in the soil and the demands of the plant, but with varying efficiency among species. Understanding and improving the ability of particular plant species to respond to and utilize nitrogen could therefore lead to increased crop productivity and decreased water and air pollution.