• The Plant Pathology Journal
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• v.31 no.4
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• pp.379-387
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• 2015

Melon necrotic spot virus (MNSV) was recently identified on watermelon (Citrullus vulgaris) in Korea, displaying as large necrotic spots and vein necrosis on the leaves and stems. The average occurrence of MNSV on watermelon was found to be 30-65% in Hapcheon and Andong City, respectively. Four isolates of the virus (MNSV-HW, MNSV-AW, MNSV-YW, and MNSV-SW) obtained from watermelon plants in different areas were non-pathogenic on ten general indicator plants, including Chenopodium quinoa, while they infected systemically six varieties of Cucurbitaceae. The virus particles purified by 10-40% sucrose density gradient centrifugation had a typical ultraviolet spectrum, with a minimum at 245 nm and a maximum at 260 nm. The morphology of the virus was spherical with a diameter of 28-30 nm. Virus particles were observed scattered throughout the cytoplasm of watermelon cells, but no crystals were detected. An ELISA was conducted using antiserum against MNSV-HW; the optimum concentrations of IgG and conjugated IgG for the assay were $1{\mu}l/ml$ and a 1:8,000-1:10,000 dilutions, respectively. Antiserum against MNSV-HW could capture specifically both MNSV-MN from melon and MNSV-HW from watermelon by IC/RT-PCR, and they were effectively detected with the same specific primer to produce product of 1,172 bp. The dsRNA of MNSV-HW had the same profile (4.5, 1.8, and 1.6 kb) as that of MNSV-MN from melon. The nucleotide sequence of the coat protein of MNSV-HW gave a different phylogenetic tree, having 17.2% difference in nucleotide sequence compared with MNSV isolates from melon.

• Plant Resources
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• v.4 no.1
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• pp.41-47
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• 2001

This study was conducted to investigate the occurrence of Soil borne wheat mosaic virus(SbWMV) in barley fields in Korea and to examine the host pathogenicity of SbWMV. By using the ELISA test, SbWMV was detected in the six regions : Suwon, Milyang, Jinju, Youngkwang, Iksan, and Chonju. SbWMV was isolated from the two strains, Albori strain from Jinju and Eunpamil strain from Milyang. SbWMV was collected from leaves showing mosaic, yellowing and necrosis stripes. SbWMV was inoculated mechanically on 1∼1.5 leaf stages with leaf-rubbing to identify the host pathogenicity of 36 Korean barley cultivars, a wheat cultivar, two rye cultivars, three Japanese barley cultivars and Chenopodium amaranticola. Viral sympoms of inoculated leaves appeared on moulted loaves about 4 to 6 weeks of inoculation. Baegdong and Tapgolbori, infected from Albori strain and Eunpamil strain infected from Samdobori showed much higher susceptibility than C. amaranticola and C. quinoa which showed ring spots and chlorotic spots respectively. Virus particles were observed by the electron microscope. They were rod-shapes, which are bipartite, of 142 nm or 281 nm in length with 20 nm diameter on infected leaves. Specific detection and identification of SbWMV was set up using the RT-PCR. PCR fragments of SbWMV(0.5kb) were obtained by using the designed primers for SbWMV RNA 2.

• Research in Plant Disease
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• v.16 no.3
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• pp.238-246
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• 2010

In 2006 fall, a preliminary survey of viruses in two important medicinal plants, Cynanchum wilfordii and C. auriculatum, was conducted on the experimental fields at the Agricultural Research and Extension Services of Chungbuk province in Korea. On each experimental fields, percentage of virus infection was ranged from 20 to 80%, and especially an average of disease incidence propagated by roots was twice higher than that by seeds. The various symptoms were observed in Cynanchum spp. plants, such as mosaic, mottle, necrosis, yellowing, chlorotic spot and malformation etc. In electron microscopic examination of crude sap extracts, filamentous rod particles with 390-730 nm were observed in most samples. The virus particles were purified from the leaves of C. wilfordii with typical mosaic symptom, and the viral RNA was extracted from this sample containing 430-845 nm long filamentous rod. To identify the viruses, reverse transcription followed by PCR with random primers was carried out. The putative sequences of P3 and coat protein of potyvirus were obtained. From a BLAST of the two sequences, they showed 26-38% and 62-72% identities to potyviruses, respectively. In SDS-PAGE analysis, the subunit of coat protein was approximately 30.3 kDa, close to the coat protein of potyvirus. In bioassay with 21 species in 7 families, Chenopodium quinoa showed local lesion on inoculated leave and chlorotic spot on upper leave, but the others were not infected. RT-PCR detection using specific primer of C. wilfordii and C. auriculatum samples, all of 24 samples with virus symptom was positive, and five out of seven samples without virus symptom were also positive. On the basis of these data, the virus could be considered as a new member of potyvirus. We suggested that the name of the virus was Keunjorong mosaic virus (KjMV) after the common Korean name of C. wilfordii.

• Korean journal of applied entomology
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• v.12 no.3
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• pp.93-107
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• 1973

Garlic (Allium sativum L.) is an important vegetable crop for the Korean people and has long been cultivated extensively in Korea. More recently it has gained importance as a source of certain pharmaceuticals. This additional use has also contributed to the increasing demand for Korean garlic. Garlic has been propagated vegetatively for a long time without control measures against virus diseases. As a result it is presumed that most of the garlic varieties in Korea may have degenerated. The production of virus-free plants offers the most feasible way to control the virus diseases of garlic. However, little is known about garlic viruses both domestically and in foreign countries. More basic information regarding garlic viruses is needed before a sound approach to the control of these diseases can be developed. Currently garlic mosaic disease is most prevalent in plantings throughout Korea and is considered to be the most important disease of garlic in Korea. Because of this importance, studies were initiated to isolate and characterize the garlic mosaic virus. Symptom expression in test plants, physical properties, purification, serological reaction and morphological characteristics of the garlic mosaic virus were determined. Results of these studies are summarized as follows. 1. Surveys made throughout the important garlic growing areas in Korea during 1970-1972 revealed that most of the garlic plants were heavily infected with mosaic disease. 2. A strain of garlic mosaic virus was obtained from infected garlic leaves and transmitted mechanically to Chenopodium amaranticolor by single lesion isolation technique. 3. The symptom expression of this garlic mosaic virus isolate was examined on 26 species of test plants. Among these, Chenopodium amaranticolor, C. quince, C. album and C. koreanse expressed chlorotic local lesions on inoculated leaves 11-12 days after mechanical inoculation with infective sap. The remaining 22 species showed no symptoms and no virus was recovered from them whet back-inoculated to C. amaranticolor. 4. Among the four species of Chtnopodium mentioned above, C. amaranticolor and C. quinoa appear to be the most suitable local lesion test plants for garlic mosaic virus. 5. Cloves and top·sets originating from mosaic infected garlic plants were $100\%$ infected with the same virus. Consequently the garlic mosaic virus is successively transmitted through infected cloves and top-sets. 6. Garlic mosaic virus was mechanically transmitted to C, amaranticolor when inoculations were made with infective sap of cloves and top-sets. 7. Physical properties of the garlic mosaic virus as determined by inoculation onto C. amaranticolor were as follows. Thermal inactivation point: $65-70^{\circ}C$, Dilution end poiut: $10^-2-10^-3$, Aging in vitro: 2 days. 8. Electron microscopic examination of the garlic mosaic virus revealed long rod shaped particles measuring 1200-1250mu. 9. Garlic mosaic virus was purified from leaf materials of C. amaranticolor by using two cycles of differential centrifugation followed by Sephadex gel filtration. 10. Garlic mosaic virus was successfully detected from infected garlic cloves and top-sets by a serological microprecipitin test. 11 Serological tests of 150 garlic cloves and 30 top-sets collected randomly from seperated plants throughout five different garlic growing regions in Korea revealed $100\%$ infection with garlic mosaic virus. Accordingly it is concluded that most of the garlic cloves and top-sets now being used for propagation in Korea are carriers of the garlic mosaic virus. 12. Serological studies revealed that the garlic mosaic virus is not related with potato viruses X, Y, S and M. 13. Because of the difficulty in securing mosaic virus-free garlic plants, direct inoculation with isolated virus to the garlic plants was not accomplished. Results of the present study, however, indicate that the virus isolate used here is the causal virus of the garlic mosaic disease in Korea.

• Korean Journal Plant Pathology
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• v.3 no.4
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• pp.291-298
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• 1987

Samples showing mosaic symptom of cowpea (Vigna sesquipedalis) with vein banding, chlorotic spot, vein yellow were collected from Chinju areas in Korea, Two viruses were distinguishable by stability in sap, host range, and relations with cells and tissues were examined under an electron microscope, Blackeye cowpea mosaic(BICMV) was sap-transmissible to 7 plant species in 2 families, Of the plants, only leguminous species were systemically infected. This virus was inactivated by heating at $50-65^{\circ}C$ for 10 min, by diluting at $10^{-4}-10^{-5}$, and aging at room temperature for 1-6 days. Preparations examined under the electron microscope by direct negative staining method(DN -method) always showed particles of flexuous filament bout 750nm in length and cytopasmic inclusions. Cytoplasmic inclusions and virus particles were also confirmed to present in the cytoplasm of a mesophyll cell by ultrathin sections of BICMV infected cowpea leaves. Cucumber mosaic virus (CMV) was transmitted by sap- inoculation on inoculated leaves of Chenopodium amaranticolor, C. quinoa producing local lesions, but non-inoculated upper leaves of Nicotiana glutinosa, Cucurbita pepo and Vigna sesquipedalis producting systemic mosaic symptoms. Electron microscopic examination of virus preparation by direct negative staining showed spherical particles of about 30nm in diameter. In ultrathin sections of CMV infected tissues, virus particles of crystalline array were found in the vacuole and a large number of virus particles were found in the cytoplasm and the plasmodesmata of mesophyll cells.

• Korean journal of applied entomology
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• v.17 no.3 s.36
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• pp.131-138
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• 1978

A virus named Cymbidium mild mosaic virus(Cy MMV), was mechanically transmitted to Chenopodium amaranticolor from the leaves of Cymbidium with mild mosaic symptoms. The virus was cultured in C. amaranticolor, in which it produced local chlorotic and ring spots, followed by systemic vein clearing with distortion. CyMMV infected 7 out of 35 species of plants. In C. amaranticolor juice infectivity was lost by heating at $90^{\circ}C$ for 10 miuntes, and by aging at$20^{\circ}C$ for 60 days, and by diluting at $10^{-6}$ when bioassayed on C. amaranticolor. CyMMV was not transmitted by Myzus persicae. The virus was purified after clarification of homogenized C. amaranticolor leaf tissues with chloroform, by differential centrifugation followed by sucrose density gradient centrifugation. Electron microscopic examination of purified preparation showed spherical particles of 28nm in diameter. The UV absorption spectrum of purified preparation was typical of u nucleoprotein (max. at 261nm. min. at 243nm), and showed 260/280=1.72 and max/min=1.26. The value of the sedimentation coefficient of the virus was S20.w=126. In gel-diffusion tests, CyMMV antiserum reacted with CarMV, but not with any of four other viruses (BBWV, CRSV, CMV, TBRV) having similar particles and properties in vitro. In ultra-thin sections of CyMMV infected tissues, a large number of virus particles were found in the cytoplasm of mesophyll cells and in xylem vessels.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.143-150
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• 2007

A new virus-like disease of tomato showing chlorotic spots, malformation and necrosis on leaves, and chlorotic blotching, rings, and necrosis on fruits was observed around Sacheon, Gyeongsangnam-do, Korea in 2004. Host range analysis could not differentiate 4 field isolates collected from tomatoes showing different symptoms but identified them as Tomato bushy stunt virus (TBSV). TBSV-tsf2 isolate induced symptoms in indicator plants similar to those caused by the TBSV-C, -S and -Nf. As the isolate could not systemically infect Chenopodium quinoa, the isolate might belong to the previously described TBSV-S isolate. TBSV-tsf2 isolate caused similar cytological alterations that were similar to that generally caused by previously reported TBSV isolates. TBSV-tsf2 isolate, however, could be considered to belong to new strain of TBSV because masses of small electron-dense patches that were not observed from the previously described TBSV. The complete nucleotide sequences of the genomic RNA of 4739 nt excluding non-translated sequences at both termini have been determined and compared to sequences of other TBSV strains. The complete nucleotide sequence identity among TBSV isolates was 98.9% to 99.7%, and to the other tombusviruses ranged from 80.8% to 94.9%. Comparison of the amino acid sequences all five ORFs with those of other TBSV strains shows a similar genomic organization, and high percentage of amino acid sequence homology with TBSV-Nf than TBSV-S isolate. Since the TBSV symptoms were only observed in Sacheon fields where imported seeds from Japan were planted, the TBSV incidence probably caused by the planting contaminated tomato seeds and thus require more through quarantine procedure to prevent settlement of TBSV in Korea. Altogether, these results support that the Korean isolate of TBSV infecting tomato might be new strain.

• Research in Plant Disease
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• v.7 no.1
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• pp.1-7
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• 2001

An isolate of Cucumber mosaic cucumovirus(CMV) was isolated from Hydrangea macrophylla for. otaksa(Sieb. et Zucc. ) Wils. showing mosaic symptoms, and designated as Hm-CMV. Hm-CMV was characterized by the tests of host range, physical properties, serological properties, RNA and coat protein compositions, and reverse transcription and polymerase chain reaction (RT-PCR) analysis. Twelve species in 4 families were used in the host range test of Hm-CMV and could be differentiated from Y-CMV used as a control CMV by the ringspot and line pattern on inoculated leaves of several tobacco plants. Thevirus produced local lesions on inoculated leaves of Chenopodium amarticolor, C. quinoa and Vigna unguiculata. The physical properties of the virus were as follows; thermal inactivation point(TIP) was 60$\^{C}$, dilution end point (DEP) was 10$\^$-3/, and longevity in vitro (LIP) was 3∼4 days. Hm-CMV was serologically identical to Y-CMV. SDS-polyaciylamide gel electrophoresis(SDS-PAGE) showed one major protein band of about 28 kDa. In RNA or dsRNA analysis, Hm-CMV consisted of four RNA or dsRNA species, but satellite RNA was not detected. In RT-PCR using CMV-common primer and CMV subgroup I-specific primer, bothe amplified expected size of about 490 bp and 200 bp DNA fragments from Hm-CMV, respectively. Restriction enzyme analysis of the 490 bp RT-PCR products using EcoR I and Msp I showed that Hm-CMV belonged to CMV subgroup I. However, Hm-CMV could be differentiated from other CMV subgroup I isolates by RNA fingerprinting by arbitrarily primed polymerase chain reaction (RAP-PCR).

• The Plant Pathology Journal
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• v.16 no.5
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• pp.269-279
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• 2000

Alfalfa mosaic alfamoviruses(AIMV) were isolated from infected potato (Solanum tuberosum) and azuki bean (Paseolus angularis) in Korea. Two AIMV isolated from potatoes were named as strain KR (AIMV-KR1 and KR2) and AIMV isolated from azuki bean was named as strain Az (AIMV-Az). Each isolated AIMV strain was characterized by using their host ranges, symptom developments, serological relations and nucleotide sequence analysis of coat protein (CP) gene. Strains KR1, KR2, and Az were readily transmitted to 20 of 22 inoculated plant species including bean, cowpea, tomato, tobacco, and potato. AIMV-KR1 and KR2 produced the typical symptoms like chlorotic or necrotic spots in Chenopodium quinoa and Solanum tuberosum cv. Superior. AIMV-Az caused bright yellow mosaic symptom and leaf malformation in Nicotiana glauca, which were different from the common mosaic symptom caused by AIMV-KR1 and KR2. Electron microscope observation of purified virus showed bacilliform virions containing a single-stranded plus-strand RNAs of 3.6, 2.6, 2.0 and 0.9 kbp in length, respectively, similar in size and appearance to those of Alfamovirus. In SDS-PAGE, the coat protein of the two viruses formed a consistent band that estimated to be about 24kDa. The CP genes of the AIMV strains, KR1, KR2, and Az have been amplified by RT-PCR using the specific primers designed to amplify CP gene from viral RNA-3, cloned and sequenced. Computer aided analysis of the amplified cDNA fragment sequence revealed the presence of a single open reading frame capable of encoding 221 amino acids. The nucleotide and peptide sequence of viral CP gene showed that strain KR1, KR2, and Az shared highest nucleotide sequence identities with AIMV strain 425-M at 97.7%, 98.2%, and 97.2%, respectively. CP gene sequences of two strains were almost identical compared with each other. Altogether, physical, serological, biological and molecular properties of the purified virus.

• Korean Journal of Plant Resources
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• v.16 no.3
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• pp.230-237
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• 2003

This study was conducted to investigate the occurrence and characterization of tobacco mosaic virus(TMV) in Chinese foxglove isolated from the field of the Chonbuk province(Jinan, Jangsu, Jeongeup). TMV was detected in all three regions and confirmed positive reaction by ELISA test. In the host range test, Chenopodium amaranticola, Nicotiana glutinosa, N. tabacum cv. 'Bright yellow', N. tabacum cv. 'KY­57, Datura stramonium were locally infected with the virus. The virus produced mosaic symptom on inoculated leaves of N. tabacum cv. 'Samson'. However, Chenopodium quinoa, Glycine max, Raphanus sativus, Cucumis sativus, Cucurbita moschata, Brassica rape and Lycopersion esculentum did not show any symptoms. TMV particles were revealed as a stiff rod shape by transmission electron microscopic(TEM) and measured as 300 nm in length with 18 nm in diameter. Total RNA was extracted from showing symptom loaves infected with TMV and the reverse transcription­polymerase chain reaction (RT­PCR) obtained 531 bp DNA product of RNA with specific primer used. The capsid protein of TMV­RE showed higher amino acid sequence homology(97.7％) with TMV­To than with TMV­P(72.2％). The capsid protein of TMV­152 showed same amino acid sequence homology with TMV­F. The result of comparison of nucleotides sequence homology between TMV­RE strain and other TMV strain showed 94％ homology with others except TMV­P(67.3％) and TMV ­ C(68.6％).