ABSTRACT
Viola mottle virus (VMoV) was discovered in Viola odorata showing symptoms of reduced growth, leaf mottling, and whitish stripes on flowers in northern Italy in 1977. This virus has been provisionally classified as a member of the genus Potexvirus based on its morphological, serological, and biological characteristics. However, since genetic information of VMoV has never been reported, the taxonomic status of this virus is unclear. Here, we report the first complete genome sequence of VMoV to clarify its taxonomic position. Its genomic RNA is 6,052 nucleotides long, excluding the 3'-terminal poly(A) tail, and has five open reading frames (ORFs) typical of potexviruses. Among potexviruses, VMoV showed the most similarity to tulip virus X (TVX) with 81.1-81.2% nucleotide and 90.4-90.7% amino acid sequence identity in ORF1 and 82.9-83.5% nucleotide and 93.2-95.2% amino acid sequence identity in ORF5. These values are much higher than the species demarcation threshold for the genus. Phylogenetic analysis also indicated that VMoV is nested within the clade of TVX isolates. These data demonstrate that VMoV and TVX are members of the same species.
Subject(s)
Plant Diseases/virology , Potexvirus/classification , Viola/virology , Whole Genome Sequencing/methods , Genome Size , Genome, Viral , Italy , Open Reading Frames , Phylogeny , Potexvirus/genetics , Potexvirus/isolation & purificationABSTRACT
Plantago asiatica mosaic virus (PlAMV) is a member of the genus Potexvirus and has an exceptionally wide host range. It causes severe damage to lilies. Here we report on the complete nucleotide sequences of two new Japanese PlAMV isolates, one from the eudicot weed Viola grypoceras (PlAMV-Vi), and the other from the eudicot shrub Nandina domestica Thunb. (PlAMV-NJ). Their genomes contain five open reading frames (ORFs), which is characteristic of potexviruses. Surprisingly, the isolates showed only 76.0-78.0 % sequence identity with each other and with other PlAMV isolates, including isolates from Japanese lily and American nandina. Amino acid alignments of the replicase coding region encoded by ORF1 showed that the regions between the methyltransferase and helicase domains were less conserved than other regions, with several insertions and/or deletions. Phylogenetic analyses of the full-length nucleotide sequences revealed a moderate correlation between phylogenetic clustering and the original host plants of the PlAMV isolates. This study revealed the presence of two highly divergent PlAMV isolates in Japan.
Subject(s)
Genome, Viral , Mosaic Viruses/genetics , Phylogeny , Potexvirus/genetics , Viral Proteins/genetics , Amino Acid Sequence , Base Sequence , Berberidaceae/virology , Chromosome Mapping , INDEL Mutation , Japan , Methyltransferases/genetics , Mosaic Viruses/classification , Mosaic Viruses/isolation & purification , Open Reading Frames , Potexvirus/classification , Potexvirus/isolation & purification , RNA Helicases/genetics , Sequence Alignment , Viola/virologyABSTRACT
An infectious agent was transmitted mechanically from samples of Viola spp. showing white mosaic and leaf deformation to Nicotiana benthamiana. dsRNA extracted from the N. benthamiana plants migrated as four specific bands that were absent in non-inoculated plants. Sequence analysis of cDNA clones generated from the second-smallest dsRNA showed the greatest similarity to the RNA3 of prune dwarf virus (PDV) (genus Ilarvirus, family Bromoviridae). However, because of differences in molecular, biological, and serological properties between this virus isolate and PDV, a new ilarvirus species, named "Viola white distortion associated virus" (VWDaV) is proposed. Specific oligonucleotides and a TaqMan(®) probe were designed for diagnostic purposes. The possible association between the virus and the original white distortion symptoms is discussed.
Subject(s)
Ilarvirus/isolation & purification , Real-Time Polymerase Chain Reaction/methods , Viola/virology , DNA Primers/genetics , DNA, Complementary/chemistry , DNA, Complementary/genetics , Ilarvirus/genetics , Molecular Sequence Data , Oligonucleotide Probes/genetics , Plant Diseases/virology , RNA, Double-Stranded/genetics , RNA, Double-Stranded/isolation & purification , RNA, Viral/genetics , RNA, Viral/isolation & purification , Sequence Analysis, DNA , Nicotiana/virology , Virology/methodsABSTRACT
Plants of Viola cornuta displaying typical virus symptoms were observed during spring 2003 in a plant nursery in Córdoba, central Argentina. Electron microscopic examinations of symptomatic leaf samples revealed the presence of isometric virus-like particles about 30 nm in diameter. Subsequent serological analysis allowed the identification of the pathogen as a subgroup I strain of Cucumber mosaic virus (CMV). These results were confirmed by antigen capture--reverse transcription--polymerase chain reaction with specific CMV primers, and digestion with a restriction enzyme. This is the first report of CMV infecting V. cornuta in Argentina.
