Nitrate reductases from red algae, compositions and methods of use thereof

An isolated polypeptide selected from the group consisting of:

• a) an isolated polypeptide comprising any one of SEQ ID NOS:
• 7, 8, 9, 10, 11 or 12 said polypeptide having NR activity;
• b) a polypeptide that is at least 70% identical to the amino acid sequence of any of SEQ ID NOS:
• 7, 8, 9, 10, 11 or 12 said polypeptide having NR activity;
• c) a polypeptide that is encoded by a nucleic acid molecule comprising a nucleotide sequence that is at least 70% identical to any one of SEQ ID NOS:
• 1, 2, 3, 4, 5 or 6 or a complement thereof, said polypeptide having NR activity;
• d) a polypeptide that is encoded by a nucleic acid molecule that hybridizes with a nucleic acid probe consisting of the nucleotide sequence of any of SEQ ID NOS:
• 1, 2 or 3, or a complement thereof following at least one wash in 0.2×SSC at 55° C. for 20 minutes, said polypeptide having NR activity;
• e) a fragment comprising at least 200 consecutive amino acids of any of SEQ ID NOS:
• 7, 8, 9, 10, 11, or 12, said polypeptide having NR activity.

A method for increasing yield in a plant, said method comprising the steps of:

• (a) introducing into plant cells a construct comprising a polynucleotide encoding a nitrate reductase (NR), wherein said NR polynucleotide is operably linked to a promoter functional in plant cells to yield transformed plant cells, and wherein the NR encoding the NR protein is selected from the group consisting of:
• (1) a polynucleotide that encodes the polypeptide of SEQ ID NO:
• 7, 8, 9, 10, 11 or 12;
• (2) a polynucleotide comprising the sequence set forth in the encoding region of SEQ ID NO:
• 7, 8, 9, 10, 11 or 12;
• and
• (3) a polynucleotide comprising at least 30 nucleotides in length which hybridizes under moderate stringency conditions to a polynucleotide of (a) or (b), wherein the conditions include hybridization in 40 to 45% formamide, 1 M NaCl, 1% SDS at 37° C. and a wash in 0.5× to 1×SSC at 55 to 60° C.;
• and
• (4) a polynucleotide having at least 70% sequence identity to SEQ ID NO:
• 1, 2, 3, 4, 5 or 6, wherein the % sequence identity is based on the entire encoding region and is determined by BLAST 2.0 under default parameters;
• and
• (5) an isolated polynucleotide degenerate from any of (1) to (4) as a result of the genetic code;
• (6) a polynucleotide complimentary to a polynucleotide of any one of (1) to (5);
• (b) regenerating a transgenic plant from said transformed plant cells, wherein said NR is expressed in the cells of said transgenic plant at levels sufficient to maintain or increase yield in said transgenic plant.