Compositions and methods for regulating abscisic acid-induced closure of plant stomata

Abstract

A novel gene, AAPK, is disclosed. Loss of function of the protein encoded by AAPK is associated with reduced sensitivity to abscisic acid-induced stomatal closure in plants. Also disclosed are transgenic plants and mutants having altered sensitivity to abscisic acid-mediated transpiration and other desirable agronomic features. The regulation of transpiration provided by the present invention is different from that of previously described mechanisms to control transpiration in plants.

1 - 25 . (canceled) 
     
     
         26 . A genetically altered plant possessing increased sensitivity to ABA-induced stomatal closure as compared with an equivalent but unaltered plant, comprising an AAPK that is increased in amount or activity as compared with the unaltered plant. 
     
     
         27 . The genetically altered plant of  claim 26 , produced by subjecting a population of plants to mutagenesis and selecting a mutagenized plant wherein the AAPK is largely nonfunctional or absent. 
     
     
         28 . The genetically altered plant of  claim 26 , produced by transforming cells of the plant with a transgene that causes the plant's endogenous AAPK to become largely nonfunctional or absent, and regenerating the plant from the transformed cells. 
     
     
         29 . The genetically altered plant of  claim 28 , wherein expression of the transgene is inducible. 
     
     
         30 - 37 . (canceled) 
     
     
         38 . A method to decrease transpiration in a plant comprising increasing amount or activity of an AAPK in guard cells of the plant, thereby increasing sensitivity of the plant to ABA-induced stomatal closure, resulting in the decreased transpiration. 
     
     
         39 . The method of  claim 38 , wherein the AAPK amount or activity is increased by the addition of at least one transgene to the plant genome. 
     
     
         40 . A fertile plant produced by the method of  claim 38 .