Manipulation of glutamine synthetases (gs) to improve nitrogen use efficiency and grain yield in higher plants

Abstract

The present invention provides polynucleotides and related polypeptides of the protein GS. The invention provides genomic sequence for the GS gene. GS is responsible for controlling nitrogen utilization efficiency in plants. Glutamine synthase sequences are provided for improving grain yield and plant growth. The invention further provides recombinant expression cassettes, host cells and transgenic plants.

1 . An isolated polynucleotide selected from the group consisting of:
 a. a polynucleotide having at least 80% sequence identity, as determined by the GAP algorithm under default parameters, to the full length sequence of a polynucleotide selected from the group consisting of SEQ ID NOS: 43, 45, 47, 49, 51 and 53; wherein the polynucleotide encodes a polypeptide that functions as a modifier of GS;   b. a polynucleotide encoding a polypeptide selected from the group consisting of SEQ ID NO: 44, 46, 48, 50, 52 and 54;   c. a polynucleotide selected from the group consisting of SEQ ID NOS: 43, 45, 47, 49, 51 and 53; and   d. A polynucleotide which is complementary to the polynucleotide of (a), (b) or (c).   
     
     
         2 . A recombinant expression cassette, comprising the polynucleotide of  claim 1 , wherein the polynucleotide is operably linked, in sense orientation, to a promoter. 
     
     
         3 . A host cell comprising the expression cassette of  claim 2 . 
     
     
         4 . A transgenic plant comprising the recombinant expression cassette of  claim 2 . 
     
     
         5 . The transgenic plant of  claim 4 , wherein said plant is a monocot. 
     
     
         6 . The transgenic plant of  claim 4 , wherein said plant is a dicot. 
     
     
         7 . The transgenic plant of  claim 4 , wherein said plant is selected from the group consisting of: maize, soybean, sunflower, sorghum, canola, wheat, alfalfa, cotton, rice, barley, millets, peanut, switchgrass, myscanthus, triticale and cocoa. 
     
     
         8 . A transgenic seed from the transgenic plant of  claim 4 . 
     
     
         9 . A method of modulating the GS in a plant, comprising:
 a. introducing into a plant cell a recombinant expression cassette comprising the polynucleotide of  claim 1  operably linked to a promoter;   b. culturing the plant cell under plant cell growing conditions; and   c. regenerating a plant form said plant cell; wherein the GS in said plant is modulated.   
     
     
         10 . The method of  claim 9 , wherein the plant is selected from the group consisting of: maize, soybean, alfalfa, barley, canola, cocoa, cotton, millets, myscanthus, peanut, rice, rye, sorghum, sugar cane, switchgrass, triticale and wheat. 
     
     
         11 . A method of decreasing the GS enzyme polypeptide activity in a plant cell, comprising:
 a. providing a nucleotide sequence comprising at least 15 consecutive nucleotides of the complement of SEQ ID NO: 43, 45, 47, 49, 51 and 53;   b. providing a plant cell comprising an mRNA having the sequence set forth in SEQ ID NO: 43, 45, 47, 49, 51 and 53; and   c. introducing the nucleotide sequence of step (a) into the plant cell, wherein the nucleotide sequence inhibits expression of the mRNA in the plant cell.   
     
     
         12 . The method of  claim 9 , wherein said plant cell is from a monocot. 
     
     
         13 . The method of  claim 12 , wherein said monocot is maize, soybean, alfalfa, barley, canola, cocoa, cotton, millets, myscanthus, peanut, rice, rye, sorghum, sugar cane, switchgrass, triticale or wheat 
     
     
         14 . The method of  claim 9 , wherein said plant cell is from a dicot. 
     
     
         15 . The transgenic plant of  claim 4 , wherein the GS enzyme activity in said plant is increased. 
     
     
         16 . The transgenic plant of  claim 15 , wherein the plant has increased seedling vigor. 
     
     
         17 . The transgenic plant of  claim 15 , wherein the plant has enhanced silk emergence. 
     
     
         18 . The transgenic plant of  claim 15 , wherein the plant has enhanced nitrogen assimilation in roots. 
     
     
         19 . The transgenic plant of  claim 15 , wherein the plant has increased seed number per plant. 
     
     
         20 . The transgenic plant of  claim 15 , wherein the plant has increased seed size and mass. 
     
     
         21 . The transgenic plant of  claim 15 , wherein the plant has seed with increased embryo size. 
     
     
         22 . The transgenic plant of  claim 15 , wherein the plant has increased nitrogen assimilation in the leaf. 
     
     
         23 . The transgenic plant of  claim 15 , wherein the plant has increased ear size. 
     
     
         24 . The transgenic plant of  claim 15 , wherein the plant has enhanced nitrogen utilization efficiency. 
     
     
         25 . The transgenic plant of  claim 15 , wherein the plant has increased nitrogen remobilization during senescence. 
     
     
         26 . The transgenic plant of  claim 15 , wherein the plant has increased nitrogen remobilization during grain development.