Methods and means for obtaining modified phenotypes

Abstract

Methods and means are provided for reducing the phenotypic expression of a nucleic acid of interest in eucaryotic cells, particularly in plant cells, by introducing chimeric genes encoding sense and antisense RNA molecules directed towards the target nucleic acid, which are capable of forming a double stranded RNA region by base-pairing between the regions with sense and antisense nucleotide sequence or by introducing the RNA molecules themselves. Preferably, the RNA molecules comprises simultaneously both sense and antisense nucleotide sequence.

1 - 38 . (Canceled)  
     
     
         39 . A method to inhibit expression of a target gene in a eukaryotic cell in vitro comprising introduction of a ribonucleic acid (RNA) into the cell in an amount sufficient to inhibit expression of the target gene, introduction of a ribonucleic acid (RNA) into the cell in an amount sufficient to inhibit expression of the target gene, wherein the RNA is a double-stranded molecule with a first strand consisting essentially of a ribonucleotide sequence which corresponds to a nucleotide sequence of the target gene and a second strand consisting essentially of a ribonucleotide sequence which is complementary to the nucleotide sequence of the target gene, wherein the first and the second ribonucleotide strands are separate complementary strands that hybridize to each other to form said double-stranded molecule, and the double-stranded molecule inhibits expression of the target gene.  
     
     
         40 . The method of  claim 39  in which the target gene is a cellular gene.  
     
     
         41 . The method of  claim 39  in which the target gene is an endogenous gene.  
     
     
         42 . The method of  claim 39  in which the target gene is a transgene.  
     
     
         43 . The method of  claim 39  in which the target gene is a viral gene.  
     
     
         44 . The method of  claim 39  in which the cell is from a plant.  
     
     
         45 . The method of  claim 39  in which at least one strand of the RNA is produced by transcription of an expression construct.