Down-regulation of a homeodomain-leucine zipper i-class homeobox gene for improved plant performance

Abstract

Methods for modulating plants using optimized ZmME293 down-regulation constructs are disclosed. Also disclosed are nucleotide sequences, constructs, vectors, and modified plant cells, as well as transgenic plants displaying increased seed and/or biomass yield, improved tolerance to abiotic stress such as drought or high plant density, improved nitrogen utilization efficiency, increased ear number and/or reduction in time to scenescence.

What is claimed is: 
     
         1 . An isolated nucleic acid comprising a promoter that functions in plants and further comprising a polynucleotide selected from the group consisting of SEQ ID NOS:
 1, 34, 37, 40, 41 and 43.   
     
     
         2 . An isolated nucleic acid comprising a polynucleotide selected from the group consisting of SEQ ID NOS: 1, 34, 37, 40, 41 and 43. 
     
     
         3 . The isolated nucleic acid of  claim 1  comprising a promoter that functions in plants, wherein the polynucleotide comprises SEQ ID NO: 1, 34, 37, 40, 41 or 43. 
     
     
         4 . The isolated nucleic acid of  claim 1  wherein said promoter is a constitutive promoter. 
     
     
         5 . The isolated nucleic acid of  claim 1 , wherein expression of the nucleic acid results in the downregulation of the expression of one or more endogenous homeodomain-leucine zipper I-class homeobox genes in a plant cell. 
     
     
         6 . A plant or plant cell comprising the isolated nucleic acid of  claim 1 . 
     
     
         7 . A plant or plant cell comprising the isolated nucleic acid of  claim 3 . 
     
     
         8 - 12 . (canceled) 
     
     
         13 . A method of increasing senescence and grain dry down in a maize plant, the method comprising reducing the expression of an endogenous ZmME293 gene in the plant wherein the ZmME293 gene encodes a polypeptide that is at least 95% identical to SEQ ID NO: 2. 
     
     
         14 . The method of  claim 13 , wherein the maize plant exhibits one or more of the following: an increase in density tolerance; an increase in yield or any combination of the foregoing, compared to a control plant. 
     
     
         15 . The method of  claim 13  wherein the ZmME293 gene comprises a nucleotide sequence selected from the group consisting of SEQ ID NO: 40, 41 and 43. 
     
     
         16 . The method of  claim 14 , increasing wherein the drought tolerance is increased in the absence of a yield penalty under non-drought conditions. 
     
     
         17 . A maize plant comprising in its genome an introduced modification that results in reduced expression of a polynucleotide that encodes a polypeptide that is at least 95% identical to SEQ ID NO: 2 as compared to a control maize plant that does not have the modification. 
     
     
         18 - 20 . (canceled) 
     
     
         21 . The plant of  claim 17 , wherein the maize plant shows increased yield under drought stress. 
     
     
         22 . The plant of  claim 17 , wherein the maize plant shows increased dry down. 
     
     
         23 . The plant of  claim 17 , wherein the maize plant shows increased drought tolerance. 
     
     
         24 . Seed produced from the maize plant of  claim 17 . 
     
     
         25 - 33 . (canceled)