Corn cDNA encoding southern leaf blight resistance

Abstract

This invention relates to an isolated nucleic acid fragment encoding a SCLB R protein. The invention also relates to the construction of a chimeric gene encoding all or a portion of the SCLB R protein, in sense or antisense orientation, wherein expression of the chimeric gene results in production of altered levels of the SCLB R protein in a transformed host cell.

What is claimed is:  
     
       1. An isolated polynucleotide comprising: 
       (a) a nucleic acid sequence a polypeptide selected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12 and SEQ ID NO: 14; and  or    
       (b) a nucleic acid sequence that is complementary to (a).  
     
     
       2. A chimeric nucleic acid sequence comprising the isolated polynucleotide of  claim 1  operably linked to at least one suitable regulatory sequence. 
     
     
       3. A transformed host cell comprising the chimeric nucleic acid sequence of  claim 2 . 
     
     
       4. A method of altering  reducing the expression level of Mlo polypeptide in a host cell, the method comprising: 
       (a) transforming a host cell with the chimeric nucleic acid sequence of  claim 2 ; and  
       (b) growing the transformed host cell of step (a) under conditions suitable for expression of the chimeric nucleic acid sequence;  
       wherein expression of the chimeric nucleic acid sequence results in production of altered  reduced Mlo polypeptide levels in the transformed host cell increasing disease resistance. 
     
     
       5. A method of obtaining an isolated polynucleotide encoding an Mlo polypeptide comprising: 
       (a) probing a cDNA or genomic library with at least  30  contiguous nucleotides of the isolated polynucleotide of  claim 1 ; and  
       (b) isolating the cDNA clone or genomic DNA clone identified in step (a);.  
     
     
       6. A method of obtaining an isolated polynucleotide encoding an Mlo polypeptide, the method comprising: 
       (a) synthesizing an oligonucleotide primer corresponding to at least 30 contiguous nucleotides of the isolated polynucleotide set forth in any of SEQ D NOs:1, 3, 5, 7, 9, 11, 13, 18 and 19; and  
       (b) amplifying a cDNA insert present in a cloning vector using the oligonucleotide primer of step (a)  
       wherein the amplified isolated polynucleotide encodes an Mlo polypeptide. 
     
     
       7. The product of the method of  claim 5 . 
     
     
       8. The product of the method of  claim 6 . 
     
     
       9. An expression cassette comprising an isolated polynucleotide of  claim 1  operably linked to a promoter. 
     
     
       10. An isolated polynucleotide comprising: 
       (a) a first nucleic acid sequence that is at least 80% identical by the Jotun Hein method of alignment to a nucleic acid molecule encoding a polypeptide set forth in SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, or SEQ ID NO:14; or  
       (b) a second nucleic acid sequence that is complementary to the first isolated polynucleotide.  
     
     
       11. A chimeric nucleic acid sequence comprising the isolated polynucleotide of  claim 10  operably linked to at leaset one suitable regulatory sequence. 
     
     
       12. A transformed host cell comprising the chimeric nucleic acid sequence of  claim 11 . 
     
     
       13. A method of altering the expression level of Mlo polypeptide in a host cell, comprising: 
       (a) transforming a host cell with the chimeric nucleic acid sequence of  claim 11 ; and  
       (b) growing the transformed host cell of step (a) under conditions that are suitable for expression of the chimeric nucleic acid sequence,  
       wherein expression of the chimeric nucleic acid sequence results in altered Mlo polypeptide levels in the transformed host cell. 
     
     
       14. A method for producing a transgenic plant, comprising: 
       (a) transforming a plant cell with an expression cassette of  claim 9 ; and  
       (b) regenerating the transformed plant cell of (a) to produce a transgenic plant.  
     
     
       15. An isolated polynucleotide as set forth in SEQ ID NOs:1, 3, 5, 7, 9, 11, or 13.