Maize chitinases and their use in enhancing disease resistance in crop plants

Abstract

The invention provides isolated chitinase nucleic acids and their encoded proteins. The present invention provides methods and compositions relating to altering chitinase levels in plants. The invention further provides recombinant expression cassettes, host cells, transgenic plants, and antibody compositions.

What is claimed is:  
     
         1 . An isolated nucleic acid encoding a polypeptide having chitinase enzyme activity, said nucleic acid comprising a member selected from the group consisting of: 
 (a) the polynucleotide sequence set forth in SEQ ID NO: 21;    (b) the polynucleotide sequence set forth in SEQ ID NO: 29;    (c) an isolated polynucleotide comprising at least 90% sequence identity to the polynucleotide of SEQ ID NO: 21, wherein said isolated polynucleotide encodes a polypeptide comprising chitinase enzyme activity;    (d) an isolated polynucleotide comprising at least 95% sequence identity to the polynucleotide of SEQ ID NO: 21, wherein said isolated polynucleotide encodes a polypeptide comprising chitinase enzyme activity;    (e) an isolated polynucleotide comprising at least 90% sequence identity to the polynucleotide of SEQ ID NO: 29, wherein said isolated polynucleotide encodes a polypeptide comprising chitinase enzyme activity;    (f) an isolated polynucleotide comprising at least 95% sequence identity to the polynucleotide of SEQ ID NO: 29, wherein said isolated polynucleotide encodes a polypeptide comprising chitinase enzyme activity; and    (g) a polynucleotide comprising the antisense nucleotide sequence corresponding to the polynucleotide of (a), (b), (c), (d), (e), or (f).    
     
     
         2 . A recombinant expression cassette, comprising the nucleic acid of  claim 1  operably linked, in sense or anti-sense orientation, to a promoter.  
     
     
         3 . A host cell comprising the recombinant expression cassette of  claim 2 .  
     
     
         4 . A transgenic plant comprising a recombinant expression cassette of  claim 2 .  
     
     
         5 . The transgenic plant of  claim 4 , wherein said plant is a monocot.  
     
     
         6 . The transgenic plant of  claim 4 , wherein said plant is selected from the group consisting of: corn, soybean, sunflower, sorghum, canola, wheat, alfalfa, cotton, rice, barley, and millet.  
     
     
         7 . A stably transformed transgenic seed from the transgenic plant of  claim 4 , wherein the seed comprises the recombinant expression cassette.  
     
     
         8 . A method of modulating the level of chitinase in a plant, comprising: 
 (a) introducing into a plant cell a recombinant expression cassette comprising the nucleic acid of  claim 1  operably linked to a promoter;    (b) culturing the plant cell under plant cell growing conditions;    (c) regenerating a plant from said plant cell; and    (d) inducing expression of said nucleic acid for a time sufficient to modulate the level of chitinase in said plant.    
     
     
         9 . The method of  claim 8 , wherein the plant is maize.  
     
     
         10 . An isolated nucleic acid encoding a polypeptide having chitinase enzyme activity, said nucleic acid comprising a member selected from the group consisting of: 
 (a) a polynucleotide sequence that encodes a polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 22;    (b) a polynucleotide sequence that encodes a polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 30; and    (c) a polynucleotide which is complementary to the polynucleotide of (a) or (b).