title: Specificity in the association of tomato black ring virus satellite RNA with helper virus.
abstract: The satellite RNAs (sat-RNAs) associated with some isolates of tomato black ring virus (TBRV) consist of single-stranded molecules of about 1375 nucleotides, encoding a nonstructural protein of 48K which has been shown to be involved in the replication of the sat-RNA. The TBRV sat-RNAs are also dependent for their replication and for their encapsidation on the helper virus. To characterize the nature of the association between sat-RNA and helper virus, transcripts of sat-RNA from TBRV isolates C and L (respectively, of serotypes G and S) have been prepared and inoculated onto Chenopodium quinoa leaves or protoplasts. Transcript of the TBRV sat-RNA C is efficiently multiplied when coinoculated with the genomic RNAs of TBRV isolate G (used instead of TBRV isolate C, because isolate G was depleted of sat-RNA), but does not multiply with TBRV isolate L. On the other hand, transcript of the sat-RNA L is able to multiply with the cognate helper virus and, less efficiently, with grapevine chrome mosaic virus (another nepovirus, 80% similar to TBRV), but does not multiply with TBRV G. The specificity of the association resides at the level of sat-RNA replication. Analysis of the multiplication of chimeric sat-RNAs, obtained by exchanging different regions between the two sat-RNAs C and L, showed that the 5' and the 3' noncoding regions of the sat-RNA, although important for replication, are not implicated in specificity. The results suggest that the determinants of the specificity are contained in the 48K sat-RNA-encoded protein.
mesh_terms: D001483:Base Sequence; D002678:Chimera; D017931:DNA Primers / Q000737:chemistry; D004279:DNA, Viral / Q000235:genetics; D006378:Helper Viruses / Q000235:genetics* / Q000502:physiology; D018551:Solanum lycopersicum / Q000821:virology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010942:Plant Viruses / Q000235:genetics* / Q000502:physiology; D010957:Plasmids; D011523:Protoplasts / Q000821:virology; D012313:RNA / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D019244:RNA, Satellite; D012367:RNA, Viral / Q000096:biosynthesis*; D013045:Species Specificity; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication / Q000502:physiology
chemical_list: D017931:DNA Primers; D004279:DNA, Viral; D019244:RNA, Satellite; D012367:RNA, Viral; D014764:Viral Proteins; D012313:RNA