• The Plant Pathology Journal
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• v.18 no.6
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• pp.317-322
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• 2002

An isolate of Odontoglossum ringspot virus (ORSV) was identified from Cymbidium var. 'Grace Kelly' showing ringspot symptom on the floral and leaf parts, and was denoted as cymbidium ringspot isolate (ORSV-CR). In ultrathin sections of leaf tissue from diseased Cymbidium plants, clusters of virus particles were observed in the vacuole and cytoplasm. In the Western blot hybridization, the virus strongly reacted with ORSV-specific antiserum indistinguishable from ORSV, suggesting that the vims is serologically identical with ORSV. ORSV-CR sap was inoculated onto 20 species belonging to 12 genera. Systemic infection occurred in Cymbidium sp., Nicotiana benthamiana and N. clevelandii, the host of which was found to be different from that of ORSV-Cy, the Korean strain of ORSV. The analysis of coat protein (CP) gene showed that ORSV-CR was highly homologous to the known isolates of ORSV, with over 95.6% identity in amino acid level. Phylogenetic tree analysis of CP showed that ORSV-CR was clustered with the known ORSV isolates, suggesting that ORSV is a very stable tobamovirus.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.498-507
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• 2019

Odontoglossum ringspot virus (ORSV) is a member of the genus Tobamovirus. It is one of the most prevalent viruses infecting orchids worldwide. Earlier studies reported the genetic variability of ORSV isolates from Korea and China. However, the evolutionary rate, timescale, and phylogeographical analyses of ORSV were unclear. Twenty-one coat protein (CP) gene sequences of ORSV were determined in this study, and used them together with 145 CP sequences obtained from GenBank to infer the genetic diversities, evolutionary rate, timescale and migration of ORSV populations. Evolutionary rate of ORSV populations was $1.25{\times}10^{-3}nucleotides/site/y$. The most recent common ancestors came from 30 year ago (95% confidence intervals, 26-40). Based on CP gene, ORSV migrated from mainland China and South Korea to Taiwan island, Germany, Australia, Singapore, and Indonesia, and it also circulated within east Asia. Our study is the first attempt to evaluate the evolutionary rates, timescales and migration dynamics of ORSV.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.559-562
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• 1998

Odontoglossum ringspot virus (ORSV) was finally purified from ORSV-infected orchid plants by diethylaminoethyl (DEAE) cellulose anion exchange column chromatography. The virus was reliably eluted by potassium chloride at the concentration from 0.1 M to 0.13 M. Partial purification was done by solubilization with Triton X-100 (allkylphenoxypolyethoxy ethanol) and precipitation with polyethylene glycol (PEG; MW 8,000). The finally purified ORSV represented one distinct homogeneous band and the molecular weight of its capsid protein was about 17,500 Dalton in electrophoretic analysis. Electron microscopy showed not only intact particles ranged from 280 nm to 340 nm in length, but also segmented particles that final 140 nm to 220 nm and even disks. Enzyme-linked immunosorbent assay (ELISA) showed that final yield was 12 mg/100 g of the infected leaves. Bioassay demonstrated that the purified ORSV had the normal infectivity to orchid plants and Nicotiana glutionsa. Based on these data, anion exchange column chromatography could be efficiently applied to the purification of ORSV and other viruses similar to ORSV.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.194-197
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• 2010

Most orchids are propagated by tissue culture. To survey the viral infection of tissue cultured Orchids, total RNA was extracted from in vitro Cymbridium and Phalaenopsis spp. collected from companies producing tissue-cultured orchids, and RT-PCR analysis was conducted with primer pairs specific to Cymbidium mosaic virus (CymMV) and Odontoglossum ring spot virus(ORSV), which are infecting wide range of orchid genera. The bulb size of Cymbidium infected with CymMV and ORSV was compared with healthy one at 10 months after planting in vitro orchids in the glasshouse. The CymMV or ORSV infection in 97 Cymbidium and 55 Phalaenopsis plants was 84.5 and 89.1 %, respectively. Mixed infection was found in 52.6 and 47.3% of Cymbidium and Phalaenopsis tested, whereas virus-free orchids were 15.5 and 10.9%, respectively. The CymMV and ORSV reduced the bulb size by 2.7-50% depending on the cultivars of Cymbidium. The both viruses caused yellowing, mottle and mosaic with or without necrosis in 4 Cymbidium cultivars.

• Journal of Plant Biology
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• v.38 no.2
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• pp.129-136
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• 1995

Complementary DNA of the genomic RNA of odontoglossum ringspot virus Cymbidium strain (ORSV-Cy) was synthesized from polyadenylated viral RNA and cloned. Selected clones containing the viral RNA-dependent RNA polymerase gene of the virus has been sequenced by automated sequencing system. The complete nucleotide sequence of an open reading frame is 1377 base pairs in length, and encodes a protein of 458 amino acids about 52, 334 D. The 52 kD protein of ORSV shares four sequence motifs characteristic of viral RNA-dependent RNA polymerase. Comparison of the ORSV 52 kD protein sequence with that of other five viruses in tobamovirus group showed 76.0 to 60.7% homologies at the amino acid level and the conservation of the four motifs betwen the viruses.

• Korean Journal Plant Pathology
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• v.14 no.2
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• pp.130-135
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• 1998

This study was carried out to detect cymbidium mosaic potexvirus (CymMV) and odontoglossum ringspot tobamovirus (ORSV) in cultivated orchid plants in Korea. The standard double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR) were carried out for detection of the viruses in the collected orchid samples. ELISA was suitable for massive-scale diagnostic method for virus detection in orchids. RT-PCR was rapid, time-saving and reliable detective method, and detection limit data showed that RT-PCR was 103 times more sensitive than ELISA. Of the 321 individual orchids representing 5 orchids genera tested by the ELISA, CymMV and ORSV were detected in 15.6% and 22.4%, and mixed infection of the both viruses with 4.9%, respectively. Of the Cymbidium plants tested, cultivated plants showed 52.5% virus infection rate with either CymMV or ORSV and both viruses.

• Applied Microscopy
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• v.24 no.3
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• pp.46-54
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• 1994

In ultrathin section of the tissue of odontoglossum ringspot virus (ORSV)-infected Cymbidium goeringii Reichenbach, ORSV particles appeared as bundles of irregular aggregates of various length which were called stacked plates or rounded plates. Virus particles were found in the cytoplasm in electron clear zones and they also found between cell wall and plasma membrane. They mainly clustered in parallel aggregates and sometimes oriented randomly. The X-bodies and paramural bodies were observed near the cell membrane and these contained vacuole-like cavities. The cell wall of infected tissue expanded largely. Some chloroplast in ORSV infected cell was irregular. No virus particle was present in mitochondria, nuclei, vacuoles, vesicles or other organelles. The plasmodesmata slightly enlarged, and virus-associated granules were present around it.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.508-520
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• 2019

Interplay between Cymbidium mosaic virus (CymMV)/Odontoglossum ringspot virus (ORSV) and its host plant Phalaenopsis equestris remain largely unknown, which led to deficiency of effective measures to control disease of P. equestris caused by infecting viruses. In this study, for the first time, we characterized viral small interfering RNAs (vsiRNAs) profiles in P. equestris co-infected with CymMV and ORSV through small RNA sequencing technology. CymMV and ORSV small interfering RNAs (siRNAs) demonstrated several general and specific/new characteristics. vsiRNAs, with A/U bias at the first nucleotide, were predominantly 21-nt long and they were derived predominantly (90%) from viral positive-strand RNA. 21-nt siRNA duplexes with 0-nt overhangs were the most abundant 21-nt duplexes, followed by 2-nt overhangs and then 1-nt overhangs 21-nt duplexes in infected P. equestris. Continuous but heterogeneous distribution and secondary structures prediction implied that vsiRNAs originate predominantly by direct Dicer-like enzymes cleavage of imperfect duplexes in the most folded regions of the positive strand of both viruses RNA molecular. Furthermore, we totally predicted 54 target genes by vsiRNAs with psRNATarget server, including disease/stress response-related genes, RNA interference core components, cytoskeleton-related genes, photosynthesis or energy supply related genes. Gene Ontology classification showed that a majority of the predicted targets were related to cellular components and cellular processes and performed a certain function. All target genes were down-regulated with different degree by vsiRNAs as shown by real-time reverse transcription polymerase chain reaction. Taken together, CymMV and ORSV siRNAs played important roles in interplay with P. equestris by down modulating the expression levels of endogenous genes in host plant.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.130-138
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• 2010

Orchid fleck virus (OFV) is an unassigned plant virus in the family Rhabdoviridae. OFV was isolated from Cymbidium sp. showing oval necrotic lesions on their leaves in Korea, and designated as OFV-NHHS1. The complete nucleotide sequence of the RNA1 (6,413 nt) (GenBank accession no. AB516442) and RNA2 (6,001 nt) (GenBank accession no. AB516441) was determined in this study. RNA1 and RNA2 contained five and one ORF respectively. RNA1 encodes nucleocapsid (N) of 49 kDa, ORF2 of 26 kDa, ORF3 of 38 kDa, ORF4 of 20 kDa and glycoprotein (G) of 61 kDa proteins, whereas RNA2 encodes a single polymerase of 212 kDa. OFV-NHHS1 shared extremely high similarity of 98.6-100% and 98.9-99.6% in nucleotidle and amino acid sequences with a Japanese isolate, OFV-so, respectively. However, the N, G and L of OFV-NHHS1 revealed 6.9-19.3%, 7.3-12.0%, and 13.4-26.6% identities to those of 29 Rhabdoviruses, respectively. To survey the infection rate of OFV in commercial orchids in Korea, 51 Cymbidium sp., 10 Phalaenopsis sp., 22 Oncidium sp. and 21 Dendrobium sp. plants that showed typical viral symptoms were collected. RT-PCR with specific primers for detection of Cymbidium mosaic virus (CymMV), ORSV and OFV showed high infection rate by ORSV alone and double infection by ORSV and CymMV. One of the orchids tested was infected with OFV. This is the first report of the complete nucleotide sequences of OFV isolated in Korea.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.145.1-145
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• 2003

This study was conducted to designing conserved regions of molecules for virus-derived resistance to transgenic Phlaenopsis orchids to protect against two major orchid viruses, Cymbidum mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV). Infected leaf samples of Phalaenopsis were randomly screened by the RT-PCR with specific primers to both of viruses. RT-PCR products of the viruses were cloned and their nucleotide sequences were determined. Multiple alignments of coat protein (CP) genes of the viruses revealed that over the 88 ％ and 94 ％ identities with CymMV and ORSV, respectively, were observed. These data can be useful for selection of highly conserved regions of CP gene of the viruses for transgenic orchid experiments.