Engineering Single-Gene-Controlled Staygreen Potential Into Plants

Abstract

The enzymes of the ACC synthase family are used in producing ethylene. Nucleotide and polypeptide sequences of ACC synthases are provided along with knockout plant cells having inhibition in expression and/or activity in an ACC synthase and knockout plants displaying a staygreen phenotype, a male sterility phenotype, or an inhibition in ethylene production. Methods for modulating staygreen potential in plants, methods for modulating sterility in plants, and methods for inhibiting ethylene production in plants are also provided.

What is claimed is: 
     
         1 . A method of making a  Zea mays  plant, the method comprising:
 introducing a genetic modification into the plant, which genetic modification reduces expression of a gene encoding an enzyme involved in ethylene synthesis in the plant and thereby increases drought tolerance, increases time for maintaining a photosynthetically active plant, and/or delays leaf senescence, compared to a control  Zea mays  plant lacking the genetic modification.   
     
     
         2 . The method of  claim 1 , wherein expression of the gene is reduced by RNA interference. 
     
     
         3 . The method of  claim 1 , wherein expression of the gene is reduced by mutagenesis of the gene. 
     
     
         4 . The method of  claim 1 , wherein the gene is an ACC synthase gene. 
     
     
         5 . The method of  claim 1 , wherein the gene is an ACC oxidase gene. 
     
     
         6 . A method of producing a desired phenotype, the method comprising:
 expressing a transgene in a  Zea mays  plant, wherein expression of the transgene reduces ethylene production in the plant and thereby increases drought tolerance, increases time for maintaining a photosynthetically active plant, and/or delays leaf senescence, compared to a control  Zea mays  plant lacking the transgene.   
     
     
         7 . The method of  claim 6 , wherein expression of the transgene reduces expression of a gene encoding an enzyme involved in ethylene synthesis. 
     
     
         8 . The method of  claim 7 , wherein the gene is an ACC synthase gene. 
     
     
         9 . The method of  claim 7 , wherein the gene is an ACC oxidase gene. 
     
     
         10 . The method of  claim 6 , wherein expression of the transgene is constitutive. 
     
     
         11 . The method of  claim 6 , wherein expression of the transgene is targeted to a specific tissue. 
     
     
         12 . The method of  claim 11 , wherein the tissue is reproductive tissue. 
     
     
         13 . The method of  claim 11 , wherein the tissue is leaf tissue. 
     
     
         14 . A  Zea mays  plant comprising a genetic modification that reduces expression of a gene encoding an enzyme involved in ethylene synthesis in the plant and thereby increases drought tolerance, increases time for maintaining a photosynthetically active plant, and/or delays leaf senescence, compared to a control  Zea mays  plant lacking the genetic modification. 
     
     
         15 . The plant of  claim 14 , wherein expression of the gene is reduced by mutagenesis of the gene. 
     
     
         16 . The plant of  claim 14 , wherein the gene is an ACC synthase or ACC oxidase gene. 
     
     
         17 . The plant of  claim 14 , wherein the genetic modification comprises expression of a transgene. 
     
     
         18 . The plant of  claim 17 , wherein expression of the transgene is constitutive. 
     
     
         19 . The plant of  claim 17 , wherein expression of the transgene is targeted to reproductive tissue. 
     
     
         20 . The plant of  claim 17 , wherein expression of the transgene is targeted to leaf tissue.