Detection and sequence of plus-strand leader RNA of sonchus yellow net virus, a plant rhabdovirus.

Tobacco infected with the plant rhabdovirus sonchus yellow net virus (SYNV) contains short, 139- to 144-nucleotide (nt) transcripts complementary to the 3' terminus of the negative-strand genomic RNA. These transcripts are similar to the leader RNAs associated with several animal rhabdovirus infections in that they are encoded by the same region of the genome, but the SYNV transcripts are nearly 3 times longer than the animal rhabdovirus leader RNAs. The SYNV leader RNAs differ markedly in sequence from the leader RNAs associated with strains of vesicular stomatitis virus and rabies virus, although the first 30 nt of all three transcripts are rich in adenylate residues. The nucleotide sequence determined directly from SYNV RNA and from recombinant DNA clones derived from SYNV RNA reveals a possible initiation site for transcription of the N-protein mRNA that is located 147 nt from the 3' end of genomic RNA. The sequence (UUGU) at this site is complementary to the first 4 nt of the N-protein mRNAs of animal rhabdoviruses. In SYNV, the first AUG codon in the putative N-protein mRNA is located 57 nt downstream (at positions 203-205 in the viral genome) and is followed by an open reading frame for the remainder of the 1020 nt determined in these experiments.