Compositions and methods for increasing enzyme activity across a broad physiological spectrum in plants, plant cells, tissues and seeds are provided. Compositions include plants or plant parts comprising two or more polynucleotides encoding polypeptides that are active across a broader physiological spectrum than when either polynucleotide is expressed alone. Vectors comprising these polynucleotide molecules as well as host cells comprising the vectors are further provided. Compositions also comprise transformed bacteria, plants, plant cells, tissues, and seeds. In addition, methods are provided for producing the plants, plant cells, tissues and seeds of the invention. Methods for increasing plant yield and methods for conferring resistance to an herbicide in a plant are further provided.