Nemesia ring necrosis virus: a new tymovirus with a genomic RNA having a histidylatable tobamovirus-like 3' end

1 Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany 2 Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands 3 Leiden Institute of Biology, Leiden University, Kaiserstraat 63, 2311 GP Leiden, The Netherlands Correspondence R. Koenig r.koenig{at}bba.de The complete nucleotide sequence of the genomic RNA of the new virus Nemesia ring necrosis virus (NeRNV), which is widespread in various ornamental plant species belonging to the Scrophulariaceae and Verbenaceae , has been determined. Based on its gene content, the folding properties of its 5'-untranslated region and in vitro translation experiments, NeRNV RNA is a typical tymovirus RNA. Its 3' end, however, differs greatly from those of the valine-specific tymoviral RNAs that have been analysed previously. It can be folded into an upstream pseudoknot domain and a histidine-specific tRNA-like structure, a combination that, so far, has been found only in tobamoviral RNAs. The identity elements found in NeRNV RNA for recognition by yeast histidyl-tRNA synthetase are more similar to those of yeast tRNA His than the ones found in tobacco mosaic virus RNA. As a result NeRNV RNA can be charged with histidine even more efficiently than tobacco mosaic virus RNA. The GenBank/EMBL/DDBJ accession number for the complete RNA sequence of a Nemesia isolate of Nemesia ring necrosis virus is AY751778 ; partial RNA sequences of Diascia and Verbena isolates of the virus have accession numbers AY751781 and AY885256 , respectively.