The NR enzymes described herein were discovered in the red algae of Porphyra perforata (PpNR) and Porphyra yezoensis (PyNR). The present invention provides methods and compositions relating to altering NR activity, nitrogen utilization and/or uptake in plants. The invention relates to a method for the production of plants with maintained or increased yield under low nitrogen fertility. The invention provides isolated nitrate reductase (NR) nucleic acids and their encoded proteins. The invention further provides recombinant expression cassettes, host cells, and transgenic plants. Plants transformed with nucleotide sequences encoding the NR enzyme show improved properties, for example, increased yield and growth.