ABSTRACT
In September 2011, the leaf samples of hosta cultivar 'Sum and substance' were collected from the collection of Gryshko' National Botanical Garden in Kyiv. The leaves showed dark green streaking and puckering along the leaf veins. Transmission electron microscopy revealed the presence of filamentous viral particles 13 nm in diameter and 470-580 nm in length. Reverse transcription PCR (RT-PCR) analysis confirmed the presence of Hosta virus X (HVX). The sequencing of the complete genome revealed 99% identity to HVX-37 and 97.5% identity to HVX-Kr. Notably, ORF4 initiation codon presented a non-conventional start codon (UUG) like it was previously identified in HVX-37.
Subject(s)
Hosta/virology , Plant Diseases/virology , Potexvirus/isolation & purification , Base Sequence , Genome, Viral , Phylogeny , Plant Leaves/virology , Plant Proteins/genetics , Potexvirus/classification , Potexvirus/genetics , Potexvirus/physiology , UkraineABSTRACT
The coat protein (CP) gene DNA sequences of nine isolates of Hosta virus X (HVX) from different regions of the Czech Republic were determined and compared with sequences available in GenBank. The sequences were almost uniform, the pairwise nucleotide identities among the Czech HVX isolates were 99-100%. The respective range was 98-100% when sequences from the GenBank were included. Therefore, phylogenetic analyses including Maximum parsimony and Bayesian analyses of either, DNA and deduced amino acid sequences, showed close relationship among isolates. Only the group of two isolates, HVXCR1 and HVXCR8 showed significant sequence divergence in phylogenetic trees. The HVXCR1-HVXCR8 group differs from the others by the substitution of glutamine (Q) by arginine (R). Moreover, these isolates showed different symptoms on infected hosta leaves - deformation on the leaves without a mosaic or mottling. This amino acid change may, therefore, have a biological significance.
Subject(s)
Hosta/virology , Plant Diseases/virology , Potexvirus/isolation & purification , Capsid Proteins/genetics , Czech Republic , Genetic Variation , Hosta/classification , Molecular Sequence Data , Phylogeny , Potexvirus/classification , Potexvirus/geneticsABSTRACT
Tobacco rattle virus from a Hosta hybrid contained one RNA1 (Ho-1) and two RNA2 species (Ho-2a, Ho-2b). Whereas Ho-1 resembles TRV Al RNA1 from Alstroemerias, Ho-2a and Ho-2b resemble TRV TpO1 RNA2 from a potato field. Ho-2a has a complete RNA2-specific sequence, whereas that of Ho2-b carries a large deletion. The short RNA1-related 3' end of Ho-2a is distinct from that of Ho-1, whereas the longer one of Ho-2b is identical to that of Ho-1. TRV RNA2 molecules may apparently become associated with different TRV RNA1 molecules, from which they can acquire 3'ends of various lengths while often losing large portions of their RNA2-specific sequences.
Subject(s)
Genome, Viral , Hosta/virology , Nicotiana/virology , Plant Diseases/virology , Plant Viruses/genetics , RNA Viruses/genetics , Reassortant Viruses/genetics , Base Sequence , Molecular Sequence Data , RNA, Viral/genetics , Recombination, Genetic , Sequence DeletionABSTRACT
Hosta virus X (HVX) is rapidly becoming a serious pathogen of commercially important hosta plants worldwide. We report here biological and molecular characterization of a U.S. isolate of HVX, HVX-37. HVX-37 infectivity was tested in 21 hosta cultivars over three growth seasons, and three types of responses were defined based upon the ability of the virus to cause local and/or systemic infections. Four cultivars resistant to systemic HVX infection were identified. The full-length sequence of the HVX-37 genome was determined, the first complete sequence of a U.S. HVX isolate. Comparison with the previously sequenced HVX-Korea (Kr) genome revealed a high level of sequence similarity, as well as some differences. Notably, a 105-nucleotide long, near-perfect direct repeat in the Kr isolate is absent in HVX-37. The accuracy of the HVX-37 genome sequence was confirmed by infectivity of in vitro transcripts synthesized from a full-length HVX-37 cDNA on Nicotiana benthamiana and hosta plants.
Subject(s)
Hosta/virology , Plant Diseases/virology , Plant Viruses/classification , Plant Viruses/genetics , DNA, Complementary/genetics , DNA, Viral/genetics , Gene Expression Regulation, Viral , Genome, Viral , Phylogeography , RNA, Viral , United StatesABSTRACT
The complete genome of Hosta Virus X (HVX), which is thought to be a distinct species of Potexvirus, was sequenced. Nucleotide sequences of HVX were compared with those of other members of the genus Potexvirus and phylogenetic tree was constructed. The range of identities of viral replicase open reading frame 1 (ORF1) between HVX and other potexviruses were 43.1%-55.1% and 35.9%-46.6% at the nucleotide and amino acid levels, respectively. Phylogenetic analysis was performed according to the amino acid sequence of the replicase to determine the position of HVX in the genus Potexvirus. Results from the phylogenetic analysis demonstrated that HVX was in the same group as Cassava common mosaic virus (CsCMV), Plantago asiatica mosaic virus (PlAMV), Tulip virus X (TVX), and Hydrangea ring spot virus (HdRSV). In particular, coat protein (CP) sequences among viruses from different Hosta cultivars were revealed to be less variable than those from different isolates of Potato virus X (PVX), a Potexvirus type species. In the present study, HVX was transmissible by seeds of the Hosta "Blue Cadet" cultivar. Moreover, HVX was detected in the embryo but not in the seed coat or endosperm of the seed.
Subject(s)
Capsid Proteins/genetics , Genetic Variation , Hosta/virology , Plant Diseases/virology , Potexvirus/classification , Potexvirus/genetics , Seeds/virology , Base Sequence , Genome, Viral , Hosta/anatomy & histology , Hosta/genetics , Molecular Sequence Data , Open Reading Frames , Phylogeny , Sequence Analysis, DNAABSTRACT
Triple gene block 1 (TGB1) and coat protein (CP) sequences of 30 hosta virus X (HVX) isolates from Tennessee (TN), USA, were determined and compared with available sequences in GenBank. The CPs of all known HVX isolates, including those from TN, shared 98.3-100% and 98.2-100% nucleotide and amino acid sequence identity, respectively, whereas TGB1 shared 97.4-100% nucleotide and 97-100% amino acid sequence identity. TGB1 of TN isolates were all longer by one codon from that of a Korean isolate, which is the only sequence publicly available. Phylogenetic analysis of nucleotide and amino acid sequences of TGB1 and CP of all known HVX isolates, separately or combined, revealed a close relationship, suggesting that all of them are derived from a common ancestor. Phylogenetic analysis with the type member of each genus of the family Flexiviridae confirmed that HVX is a member of a distinct species of the genus Potexvirus.
Subject(s)
Genetic Variation , Hosta/virology , Phylogeny , Plant Diseases/virology , Potexvirus , Capsid Proteins/genetics , Molecular Sequence Data , Potexvirus/classification , Potexvirus/genetics , Potexvirus/isolation & purification , Sequence Analysis, DNA , Species Specificity , Tennessee , Viral Proteins/geneticsABSTRACT
Apotexvirus, Hosta virus X (HVX-Kr), causing mosaic and mottle symptoms was isolated from hosta plants ( Hosta spp.) in Korea. The 3'-terminal 2,711 nucleotides excluding the poly (A) tail were determined and shown to include the partial viral replicase, triple gene block (TGB) 1 (26 kDa), TGB2 (13 kDa), TGB3 (8 kDa), and 23 kDa coat protein (CP) and the 3'-nontranslated region (NTR), typical of potexviruses. The CP gene of the type isolate of HVX (HVX-U) was amplified by RT-PCR and its nucleotide sequence was determined. The CPs of HVX-Kr and HVX-U had 100% and 98.9% identical amino acids and nucleotides, respectively. Most of the regions of the genome HVX had over 50% nucleotide identical to other sequenced potexviruses. This is the first report of sequence information of HVX and molecular evidence supporting the virus as a distinct species of the genus Potexvirus.