Methods for modulating water-use efficiency or productivity in a plant

Abstract

A method for modulating water-use efficiency or productivity in a plant is provided. In particular, stomatal aperture in a plant can be regulated by transforming the plant with a polynucleotide capable of modifying malate accumulation in the plant.

That which is claimed:  
     
         1 . A method for decreasing steady-state stomatal conductance in a plant comprising: 
 a) transforming a plant cell with a polynucleotide operably linked to a promoter that drives expression in a plant cell, wherein said polynucleotide encodes NADP-malic enzyme and wherein the expression of said polynucleotide decreases malate accumulation in the plant cell;    b) regenerating plants from the transformed cell; and    c) selecting for regenerated plants having a decrease in steady-state stomatal conductance or an increase in water-use efficiency.    
     
     
         2 . The method of  claim 1 , wherein said polynucleotide is operably linked to a DNA sequence encoding a transit peptide.  
     
     
         3 . The method of  claim 1 , wherein said plant is selected from the group consisting of maize, soybean, sorghum, sunflower, alfalfa, canola, safflower, tomato, wheat, rice, peanut, and cotton.  
     
     
         4 . A method for increasing water-use efficiency in a plant comprising: 
 a) transforming a plant cell with a polynucleotide operably linked to a promoter that drives expression in a plant cell, wherein said polynucleotide encodes NADP-malic enzyme and wherein the expression of said polynucleotide decreases malate accumulation in the plant cell;    b) regenerating plants from the transformed cell; and    c) selecting for regenerated plants having a decrease in steady-state stomatal conductance or an increase in water-use efficiency.    
     
     
         5 . The method of  claim 4 , wherein said polynucleotide is operably linked to a DNA sequence encoding a transit peptide.  
     
     
         6 . The method of  claim 4 , wherein said plant is selected from the group consisting of maize, sorghum, soybean, sunflower, alfalfa, canola, safflower, tomato, wheat, rice, peanut, and cotton.  
     
     
         7 . A transformed plant comprising an isolated polynucleotide stably integrated into the plant genome, wherein: 
 a) said polynucleotide is operably linked to a promoter that drives expression in a plant cell;    b) said polynucleotide encodes NADP-malic enzyme;    c) the expression of said polynucleotide decreases the level of malate in the plant cell; and    d) the plant has a decrease in steady-state stomatal conductance or an increase in water-use efficiency as compared to an untransformed plant.    
     
     
         8 . The plant of  claim 7 , wherein the malate level is decreased by at least about 5%.  
     
     
         9 . The plant of  claim 7 , wherein the malate level is decreased by at least about 10%.  
     
     
         10 . The plant of  claim 7 , wherein the malate level is decreased from about 15% to about 65%.  
     
     
         11 . The plant of  claim 7 , wherein stomatal conductance is decreased at least about 5%.  
     
     
         12 . The plant of  claim 7 , wherein stomatal conductance is decreased at least about 10%.  
     
     
         13 . The plant of  claim 7 , wherein stomatal conductance is decreased from about 15% to about 80%.  
     
     
         14 . The plant of  claim 7 , wherein stomatal conductance is decreased from about 15% to about 65%.  
     
     
         15 . The plant of  claim 7 , wherein water-use efficiency is increased by at least about 5%.  
     
     
         16 . The plant of  claim 7 , wherein water-use efficiency is increased by at least about 10%.  
     
     
         17 . The plant of  claim 7 , wherein water-use efficiency is increased in the range of from about 10% to about 20%.  
     
     
         18 . The plant of  claim 7 , wherein said polynucleotide is operably linked to a DNA sequence encoding a transit peptide.  
     
     
         19 . The plant of  claim 7 , wherein said plant is selected from the group consisting of maize, sorghum, soybean, sunflower, safflower, alfalfa, canola, tomato, wheat, rice, peanut, and cotton.