Title: Complete nucleotide sequences and genome characterization of a novel double-stranded RNA virus infecting Rosa multiflora.
Authors: Salem, Nida M.; Golino, Deborah A.; Falk, Bryce W.; Rowhani, Adib.
Authors affiliation: Department of Plant Pathology, University of California, One Shields Avenue, Davis, CA, USA. Archives of Virology volumn 153(3), pages 455-462, (2008).
Abstract: "The three double-stranded (ds) RNAs were detected in Rosa multiflora plants showing rose spring dwarf (RSD) symptoms. Northern blot anal. revealed three dsRNAs in prepns. of both dsRNA and total RNA from R. multiflora plants. The complete sequences of the dsRNAs (referred to as dsRNA 1, dsRNA 2 and dsRNA 3) were detd. based on a combination of shotgun cloning of dsRNA cDNAs and reverse transcription-polymerase chain reaction (RT-PCR). The largest dsRNA (dsRNA 1) was 1,762 bp long with a single open reading frame (ORF) that encoded a putative polypeptide contg. 479 amino acid residues with a mol. mass of 55.9 kDa. This polypeptide contains amino acid sequence motifs conserved in the RNA-dependent RNA polymerases (RdRp) of members of the family Partitiviridae. Both dsRNA 2 (1,475 bp) and dsRNA 3 (1,384 bp) contained single ORFs, encoding putative proteins of unknown function. The 5’ untranslated regions (UTR) of all three segments shared regions of high sequence homol. Phylogenetic anal. using the RdRp sequences of the various partitiviruses revealed that the new sequences would constitute the genome of a virus in family Partitiviridae. This virus would cluster with Fragaria chiloensis cryptic virus and Raphanus sativus cryptic virus 2. We suggest that the three dsRNA segments constitute the genome of a novel cryptic virus infecting roses; we propose the name Rosa multiflora cryptic virus (RMCV). Detection primers were developed and used for RT-PCR detection of RMCV in rose plants. "
In the body of the paper are the following points:
page 460, in the Discussion section - “The origin and agronomic significance of cryptic viruses are still open questions. The natural vectors of these viruses are unknown. They generally appear to have no impact upon host fitness. Their agronomic significance may be found to lie in their potentiation of the symptoms of other viruses with which they co-infect plants. However, although plants expressing rose spring dwarf symptoms are usually found to contain both RMCV and RSDaV lutervirus (here a reference to an in-press paper is given), we have shown that rose spring dwarf symptoms are expressed in RSDaV-infected hosts that do not contain RMCV.”
They they go on to discuss the possibility that fungi could be the source of the spread of the virus.
page 455, in the Introduction section - “Cryptoviruses have no known natural vectors. They are transmitted between plant hosts by the ovule and by pollen to the seed embryo, but there is no graft-transmission and apparently no cell-to-cell transport.”…“they expand their coverage of their host along with the host’s cell devision. The only known mode of transmission is by seed. The highest levels of seed transmission (100%) are obtained when both parents are infected (then a reference is given).”
page 460, in the Discussion section - “These dsRNAs persisted in rose through thermotreatment (then a reference is given).”
For other related information, see David’s comments in the following thread:
http://www.rosehybridizers.org/forum/message.php?topid=14084#14229
Link: www.rosehybridizers.org/forum/message.php?topid=14084#14229