Recombinant plant viral nucleic acids

A biologically functional plasmid or viral DNA vector comprising:

• a first nucleotide sequence and a second nucleotide sequence which are means for initiating RNA synthesis, a third nucleotide sequence as an encoding means for U1-coat protein, and a fourth nucleotide sequence as a restriction enzyme cloning site means wherein the first nucleotide sequence initiates RNA synthesis from foreign DNA inserted into a cloning site of the fourth nucleotide sequence, the second nucleotide sequence initiates RNA synthesis from the third nucleotide sequence, and the first and second nucleotide sequences are heterologous with respect to one another.

A recombinant plant viral nucleic acid comprising a native plant viral subgenomic promoter, at least one non-native plant viral subgenomic promoter and a plant viral coat protein coding sequence, wherein said native plant viral subgenomic promoter initiates transcription of an operably joined nucleic acid sequence and said non-native plant viral subgenomic promoter initiates transcription of the plant viral coat protein sequence in a host plant and wherein said non-native plant viral subgenomic promoter is incapable of recombination with any other subgenomic promoter of said recombinant plant viral nucleic acid and said recombinant plant viral nucleic acid is expressed systemically in a host plant.