A new Ilarvirus found in rose

Rose rosette, a devastating disease in the midwestern and southeastern United States, is vectored by the eriophyoid mite Phyllocoptes fructiphilus and the causal agent is believed to be a virus (Ahn et al., 1996). In an attempt to characterise the causal agent of the disease, double stranded RNA (dsRNA) was isolated from diseased plants. One of the plants assayed gave a dsRNA band pattern similar to that of viruses in the Bromoviridae family. DsRNA was cloned as described (Tzanetakis et al., 2005) and several clones were sequenced to determine the origin of the bands. Sequence analysis indicated that a new virus can infect rose. The novel virus, named hereafter Rose virus 1 (RsV-1) shared about 70% nucleotide identities with Strawberry necrotic shock virus (SNSV) and Tobacco streak virus (TSV) and less than 50% identities with the other two rose-infecting ilarviruses, Prunus necrotic ringspot virus and Apple mosaic virus. Regions of RsV1 RNA 1 (591 bp) and 3 (1202 bp) have been deposited in GenBank under accession numbers DQ329377 and DQ329378 respectively.

Primers F (5' GTTTCCTGTGCTCCTCA 3') and R (5' GTCACACCGAGGTACT 3') were developed for reverse transcription-polymerase chain reaction detection of RsV1. The primers amplify a 519-base fragment of RNA 3 and were used on both total RNA and dsRNA templates. Amplicons obtained from both templates were sequenced and were RsV-1 specific. The rest of the rose rosette diseased plants used for dsRNA extractions were also tested for the virus but no amplicons were obtained; verification that RsV-1 is not the causal agent of rose rosette, as expected from previous observations (Ahn et al., 1996). The detection protocol can be employed in rose virus certification schemes and surveys, while further work is needed in order to identify the possible involvement of the virus in rose and rosaceous host diseases, in a similar situation to that identified in Rubus and Fragaria species with TSV and SNSV (Tzanetakis et al., 2004).

While this report was under review, sequence of a novel virus from blackberry, Blackberry chlorotic ringspot virus (BCRV), was released in GenBank (Accession numbers DQ091193-5; Jones et al., In Press; S.W. Scott, personal communication). The two viruses share 85-90% nucleotide identity (85-93% amino acid identity) and should be therefore considered strains of the same virus. For simplicity reasons, RsV-1 was renamed to BCRV in GenBank.