Compositions and methods for expression of a heterologous nucleotide sequence in plants

Abstract

The present invention provides compositions and methods for targeting polypeptides to the chloroplasts of higher plants. Compositions include expression cassettes having a nucleotide sequence encoding a chloroplast targeting peptide (CTP) operably linked to a nucleotide sequence of interest, wherein the CTP is derived from Chlamydomonas sp. Plant transformation vectors, plants and plant cells having the CTP sequences are also encompassed, as well as variants and fragments of the CTP sequences. Methods for expressing a heterologous nucleotide sequence in a plant using the CTP sequences disclosed herein are also provided.

That which is claimed: 
     
         1 . A plant cell having stably incorporated into its genome an expression cassette comprising a nucleotide sequence encoding a chloroplast targeting peptide (CTP), wherein said nucleotide sequence encoding said CTP is operably linked to a nucleotide sequence of interest, and wherein said nucleotide sequence encoding said CTP is selected from the group consisting of:
 a) the nucleotide sequence set forth in SEQ ID NO:1 or 2;   b) a nucleotide sequence encoding the amino acid sequence set forth in SEQ ID NO:3; and,   c) a nucleotide sequence encoding an amino acid sequence having at least 90% sequence identity to SEQ ID NO:3, wherein said amino acid sequence is a chloroplast transit peptide.   
     
     
         2 . The plant cell of  claim 1 , wherein said plant cell is from a monocot. 
     
     
         3 . The plant cell of  claim 1 , wherein said plant cell is from a dicot. 
     
     
         4 . A plant comprising the plant cell of  claim 1 . 
     
     
         5 . The plant of  claim 4 , wherein said plant is a monocot. 
     
     
         6 . The plant of  claim 4 , wherein said plant is a dicot. 
     
     
         7 . A seed derived from the plant of  claim 7 , wherein said seed comprises the nucleotide sequence encoding said chloroplast transit peptide. 
     
     
         8 . The plant cell of  claim 1 , wherein the nucleotide sequence of interest encodes a gene product that confers herbicide, pathogen, or insect resistance. 
     
     
         9 . A method for expressing a nucleotide sequence of interest in a plant, said method comprising:
 a) introducing into a plant cell an expression cassette comprising a nucleotide sequence encoding a chloroplast targeting peptide (CTP), wherein said nucleotide sequence encoding said CTP is operably linked to said nucleotide sequence of interest, and wherein said nucleotide sequence encoding said CTP is selected from the group consisting of
 i) the nucleotide sequence set forth in SEQ ID NO:1 or 2; 
 ii) a nucleotide sequence encoding the amino acid sequence set forth in SEQ ID NO:3; and, 
 iii) a nucleotide sequence encoding an amino acid sequence having at least 90% sequence identity to SEQ ID NO:3, wherein said amino acid sequence is a chloroplast transit peptide; and, 
   b) regenerating a transformed plant from said plant cell;   
       wherein said plant has stably incorporated into its genome said expression cassette. 
     
     
         10 . The method of  claim 9 , wherein said plant is a dicot. 
     
     
         11 . The method of  claim 9 , wherein said plant is a monocot. 
     
     
         12 . The method of  claim 9 , wherein said nucleotide sequence of interest encodes a gene product that confers herbicide or pest resistance.