Disclosed is a transgenic plant comprising an omega-amidase transgene, wherein the omega-amidase transgene is operably linked to a root-preferred promoter. Also disclosed is a method for increasing nitrogen use efficiency of a plant relative to a wild type or untransformed plant of the same species, comprising: (a) introducing an omega-amidase transgene into the plant, wherein the omega-amidase transgene is operably linked to a root-preferred promoter (b) expressing the omega-amidase transgene in root tissue of the plant or the progeny of the plant and (c) selecting a plant having an increased leaf-to-root ratio of 2-oxoglutaramate relative to a plant of the same species that does not comprise an omega-amidase transgene, wherein the increased leaf-to-root ratio of 2-oxoglutaramate results in increased nitrogen use efficiency.
