Root-preferred promoters and their use

Abstract

The present invention provides compositions and methods for regulating expression of heterologous nucleotide sequences in a plant. Compositions include a novel nucleotide sequence for a root-preferred promoter for the gene encoding Knox1, a Kn1-like homeobox gene and sequences isolated therefrom. A method for expressing a heterologous nucleotide sequence in a plant using the promoter sequences disclosed herein is provided. The method comprises stabling incorporating into the genome of a plant cell a nucleotide sequence operably linked to the root-preferred promoter of the present invention and regenerating a stably transformed plant that expresses the nucleotide sequence.

That which is claimed:  
     
         1 . An isolated promoter that is capable of driving gene expression in a plant cell, wherein said promoter comprises a nucleotide sequence selected from the group consisting of: 
 (a) a fragment of the nucleotide sequence set forth in SEQ ID NO: 1, wherein said fragment retains promoter activity;    (b) a nucleotide sequence having at least 80% nucleotide sequence identity to the nucleotide sequence set forth in SEQ ID NO: 1; and    (c) a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence set forth in SEQ ID NO: 1, said stringent conditions comprising hybridization at 37° C. in a solution comprising 50% formamide, 1 M NaCl, and 1% SDS, and at least one wash at 60° C. in a solution comprising 0.1×SSC;    wherein said promoter is capable of driving root-preferred expression of an operably linked nucleotide sequence.    
     
     
         2 . The isolated promoter of  claim 1 , wherein said promoter comprises a nucleotide sequence having at least 85% nucleotide sequence identity to the sequence set forth in SEQ ID NO: 1.  
     
     
         3 . The isolated promoter of  claim 1 , wherein said promoter comprises a nucleotide sequence having at least 90% nucleotide sequence identity to the sequence set forth in SEQ ID NO: 1.  
     
     
         4 . The isolated promoter of  claim 1 , wherein said promoter comprises a nucleotide sequence having at least 95% nucleotide sequence identity to the sequence set forth in SEQ ID NO: 1.  
     
     
         5 . An expression cassette comprising the promoter of  claim 1 , said promoter operably linked to a nucleotide sequence of interest.  
     
     
         6 . An expression vector comprising the expression cassette of  claim 5 .  
     
     
         7 . A plant having stably incorporated into its genome an expression cassette comprising a promoter operably linked to a nucleotide sequence of interest, wherein said promoter is capable of driving root-preferred expression of said nucleotide sequence of interest and said promoter comprises a nucleotide sequence selected from the group consisting of: 
 (a) a fragment of the nucleotide sequence set forth in SEQ ID NO: 1, wherein said fragment retains promoter activity;    (b) a nucleotide sequence having at least 80% nucleotide sequence identity to the nucleotide sequence set forth in SEQ ID NO: 1; and    (c) a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence set forth in SEQ ID NO: 1, said stringent conditions comprising hybridization at 37° C. in a solution comprising 50% formamide, 1 M NaCl, and 1% SDS, and at least one wash at 60° C. in a solution comprising 0.1×SSC.    
     
     
         8 . The plant of  claim 7 , wherein said promoter comprises a nucleotide sequence having at least 85% nucleotide sequence identity to the sequence set forth in SEQ ID NO: 1.  
     
     
         9 . The plant of  claim 7 , wherein said promoter comprises a nucleotide sequence having at least 90% nucleotide sequence identity to the sequence set forth in SEQ ID NO: 1.  
     
     
         10 . The plant of  claim 7 , wherein said promoter comprises a nucleotide sequence having at least 95% nucleotide sequence identity to the sequence set forth in SEQ ID NO:1.  
     
     
         11 . The plant of  claim 7 , wherein said plant is a monocot.  
     
     
         12 . The plant of  claim 11 , wherein said monocot is maize.  
     
     
         13 . The plant of  claim 7 , wherein said plant is a dicot.  
     
     
         14 . Seed of the plant of  claim 7 , said seed comprising said expression cassette.  
     
     
         15 . A method for expressing a nucleotide sequence of interest in a plant, said method comprising, stably incorporating into the genome of a plant cell an expression cassette comprising the promoter of  claim 1  operably linked to a nucleotide sequence of interest, wherein said promoter is capable of initiating transcription of said nucleotide sequence of interest in a root-preferred manner.  
     
     
         16 . The method of  claim 15 , wherein said nucleotide sequence of interest is selectively expressed in the root.  
     
     
         17 . A plant cell having stably incorporated into its genome an expression cassette comprising a promoter operably linked to a nucleotide sequence of interest, wherein said promoter is capable of initiating transcription of said nucleotide sequence of interest in a root-preferred manner and said promoter comprises a nucleotide sequence selected from the group consisting of: 
 (a) a fragment of the nucleotide sequence set forth in SEQ ID NO: 1, wherein said fragment retains promoter activity;    (b) a nucleotide sequence having at least 80% nucleotide sequence identity to the nucleotide sequence set forth in SEQ ID NO: 1; and    (c) a nucleotide sequence that hybridizes under stringent conditions to the nucleotide sequence set forth in SEQ ID NO: 1, said stringent conditions comprising hybridization at 37° C. in a solution comprising 50% formamide, 1 M NaCl, and 1% SDS, and at least one wash at 60° C. in a solution comprising 0.1×SSC.    
     
     
         18 . The plant cell of  claim 17 , wherein said plant cell is from a monocotyledonous plant.  
     
     
         19 . The plant cell of  claim 18 , wherein said monocotyledonous plant is maize.  
     
     
         20 . The plant cell of  claim 17 , wherein said plant cell is from a dicotyledonous plant.