• The Plant Pathology Journal
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• v.17 no.1
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• pp.22-28
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• 2001

Barley yellow dwarf virus PAV (BYDV-PAV) has a 5.7-kb positive-sense single-stranded RNA genome that contains six open reading frames (ORFs). BYDV-PAV produces three subgenomic RNAs (sgRNAs). The largest of which encodes the coat, 17-kDa, and readthrough proteins from two initiation codons. To investigate the role of intergenic and 3'-proximal noncoding regions (NCRs) in coat protein (CP) expression and BYDV-PAV replication, a full-length infectious cDNA of the RNA genome of an Illinois isolate of BYDV-PAV was constructed downstream of the Cauliflower mosaic virus-35S promoter. Linear DNA molecules of these cDNAs were infectious, expressed the 22-kDa CP, and produced both genomic RNA sgRNAs in ratios similar to those observed in protoplasts inoculated with viral RNA. The portion of 5'NCR of sgRNA1 between ORFs 2 and 3 was not required for, but enhanced translation of CP from ORF3. Mutants containing deletions in the NCR downstream of ORF5 failed to replicate in oat protoplasts. These results indicate that an intact 3$^1$NCR is required for BYDV-PAV replication.

• Journal of Korean Society of Forest Science
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• v.49 no.1
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• pp.32-33
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• 1980

Several plants of Populus deltoides 'R-89' exhibiting symptoms of poplar mosaic described earlier by several researchers (1,2,3) were observed in the poplar nursery of the Institute of Forest Genetics at Suweon, Korea during September, 1980. The symptoms produced a mosaic or discolored yellow spottings in mature leaves with veinal and petiolar necrosis and leaf curling (Fig. 1 and 2). Leaves with mosaic symptoms were collected and leaf-dip preparations from chlorotic area were examined for the presence of virus particles with an electron microscope. Electron micrographs of the negatively stained leaf-dip preparations revealed numerous elongated virus particles ranging 200-1300nm in length (Fig. 3). Of 156 panicles measured randomly, 68 particles (43.6%) were in the range of 660-670nm in length (Fig. 4). The values obtained fell well within the range of those described for poplar mosaic virus (PMV) by other researchers (1. 2, 3). No viruslike particles were observed from poplar leaves without mosaic symptoms. Further studies on the properties of the PMV isolate and control of the disease are underway.

• The Plant Pathology Journal
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• v.36 no.4
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• pp.364-377
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• 2020

Sugarcane is an important sugar crop contributes more than 80% of world sugar production. Mosaic, leaf fleck, and yellow leaf (YL) are the major viral diseases affecting sugarcane, amongst YL occurrence is widely reported in all the sugarcane growing countries. It is caused by Sugarcane yellow leaf virus (SCYLV) and detailed works were done on complete genome characterization, transmission, and management. However, in countries like Egypt, South Africa, Cuba, Mauritius and Hawaii, the disease was reported to the cause of sugarcane yellow leaf phytoplasma (SCYP) and/or SCYLV as single/combined infections. Hence, we have investigated in detail to identify the exact Candidatus phytoplasma taxon associated in Indian cultivars affected with YL. The sequencing results and the restriction fragment length polymorphism pattern of the PCR products using the universal phytoplasma primers confirmed presence of sugarcane grassy shoot (SCGS) phytoplasma (16SrXI group) in the YL-affected plants. Mixed infection of SCYLV and SCGS phytoplasma was estimated as 32.8% in YL affected plants. Evolutionary genetic relationship between SCYP and SCGS phytoplasma representatively taken from different countries showed that SCYP from South Africa and Cuba were diverged from others and had a highest similarity with SCGS phytoplasma. Although we wanted to identify SCYP from YL affected Indian sugarcane cultivars, the study clearly indicated a clear absence of SCYP in YL affected plants and we found SCYLV as the primary cause for the disease.

• 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.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.298-308
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• 2009

A flexuous rod-shaped virus was isolated from Cucurbita pepo leaves showing as green mosaic and puckering symptoms at Anseong, Korea. Based on the biological analysis, electron microscopy, and reverse transcription-polymerase chain reaction (RT-PCR), the virus isolate was identified as Papaya ringspot virus type watermelon (PRSV-W). From biological analysis, the host range of PRSV-W was limited to the families Cucurbitaceae and Chenopodiaceae. Most susceptible cucurbit species, such as Cucumis lanatus, Cucumis sativus, Cucurbita pepo, and Citrullus lanatus, showed symptoms of green mosaic, malformation, puckering, and narrow laminae by infection with PRSV-W. The local lesion were showed on the inoculated leaves of both Chenopodium amaranticolor and C. quinoa. Field survey of PRSV, Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV), three major viruses infecting cucurbit, was done during 2001 to 2003 on 173 commercial cucurbit cultivating fields distributed over the three regions of Gyeonggi, Gyeongbuk and Jeonnam Provinces where cucurbits are grown in different environmental conditions and cropping patterns. Typical viral symptoms were observed from 107 cultivating fields, and all three kinds of potyviruses were detected from 206 samples out of the 235 samples using RT-PCR. Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV) are the most widely distributed viruses in outdoor and retarding-culture fields, at an infection rating of 48 and 33 percents, respectively. PRSV was detected from 12 percent of 235 samples. The nucleotide and amino acid sequences of coat proteins (CP) of eight PRSV isolates, collected from several areas including Anseong, were determined and sequenced heterogeneity among the isolates was performed. The CP gene of PRSV showed 88.6~97.3 percent homology in nucleotide sequences and 95.1~99.3 percent homology in amino acid sequences with other PRSV isolates worldwide. The phylogenetic analysis indicated that the Korean PRSV isolates belong to the southern-east Asian cluster.

• The Plant Pathology Journal
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• v.25 no.3
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• pp.231-235
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• 2009

Viral infections and root growth were examined to elucidate the relationship between viral resistance and root growth in 26 Korean hulless barley cultivars. Viral resistance was estimated in experimental filed of Honam agricultural research institute for 3 years. Length and number of seminal and adventitious roots were examined for evaluation of root growth in both field and green-house conditions 30 days after seeding. Dominant viral infection occurred in Korean hulless barley by Barley yellow mosaic virus (BaYMV) in fields; however, susceptible cultivars were infected by either BaYMV, Barley mild mosaic virus (BaMMV) or both. Only four cultivars, including Donghanchalssalbori, Kwangwhalssalbori, Namhossalbori and Naehanssalbori, presented stable resistance to viral infections. Susceptible cultivars to viral infection in fields showed shorter seminal root length and fewer adventitious root number than resistant cultivars. Resistant cultivars showed better root growth and significant difference in adventitious root length in green house conditions. Increase in the number of seminal roots in resistant cultivars was derived from decreased damage of roots by the viral infection compared to the susceptible cultivars.

• Korean Journal Plant Pathology
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• v.1 no.1
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• pp.33-37
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• 1985

A yellow stripe and bud benting disease of soybean was commonly observed on the field at Suweon area. The causal agent was identified as alfalfa mosaic virus (AMV) by indicator plant reactions, physical properties, serological test and electron microscopy. AMV produced vein clearing, top necrosis, top bent and mottling on the parts of soybean plants. Local lesions were produced on the inoculated leaves of Vigna sesquipedialis, Vicia faba and Tetragonia expansa, while Chenopodium am, anticolor, C. quinoa, Pisum satvium, Petunia hybrida and Nicotiana tabacum 'Bright yellow' were systemically infected. The thermal inactivation point was $60^{\circ}C$, dilution end point was $10^{-3}$, and longevity in vitro was 2 days at room temperature. AMV from soybean was reacted with AMV - antiserum in agar gel diffusion test. Electron microscopy of AMV from soybean exhibited bacilliform particles of 60nm in length.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.181-184
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• 2000

This study was carried out to investigate the influence of barley yellow mosaic virus(BaYMV) on agronomic characters in naked barley. A naked barley cultivar, Beagdong was evaluated for disease systems at naturally infected field, National Honam Agricultural Experiment Station. SPAD value of the infected plants by BaYMV was low as compared to healthy plants. Heading time was delayed by 10-11 days. Dry matter weight per plant, culm length, and number of spike per plant were reduced in the infected plants by 75%, 68%, and 49%, respectively. Length of internode was reduced in the first to the sixth internode from the upper part, especially, that in the third to the fifth internode was mostly reduced by 75-80%. Also, length of awn, number of kernels, 1000-kernel weight, and kernel weight per plant of the infected plant were reduced by 17-19%, 47%, 60%, and 78%, respectively. Lightness and redness for kernel color value of Baegdong were low and high, respectively.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.97-102
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• 2006

A virus causing vein banding, sometimes yellow mosaic and rugose symptoms on peanut was prevalent around Suwon, Korea. A survey conducted in the area found disease incidence, depending on cultivar, to range from 79 to $100\%$. The virus was found to be seed-transmissible in all the five peanut cultivars tested with transmission rates ranging from 2 to $16\%$. Host range analysis failed to differentiate 9 field isolates collected from different peanuts cultivars showing various symptoms. Inclusion bodies such as scroll, pinwheel and long laminated aggregates induced by the virus in host plant cells were similar to those induced by members of the Potyvirus subdivision III. The virus showed < $95\%$ homology with Bean common mosaic virus (BCMV), BCMV-BICMV/AzMV strains and only < $91\%$ with Desmodium mosaic virus. Based on biological characterization, electron microscopy and molecular analyses of a Korean isolate (Daewon 1), the virus was identified as peanut stripe strain of BCMV.

• The Plant Pathology Journal
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• v.22 no.2
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• pp.147-151
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• 2006

Disease incidences of cucumber virus diseases in Jeonnam province were 52.5%, 16.1%, 35.2%, and 50.9% in 1999, 2000, 2001, and 2002, respectively. Rod- and flexuous rod-shaped virus particles were observed with the frequencies of 63.2% and 10.5%, respectively from the samples collected in 1999 under EM observation. Rod-shaped virus particles are considered as tobamovirus while flexuous rod shaped particles are considered as potyviruses. To further confirm their nature, total of 312 diseased virus samples were collected from 2000 to 2002, and tested by RT-PCR. Disease incidences of tobamoviruses including Cucumber green mottle mosaic virus and Kyuri green mottle mosaic virus were 48.7% and 3.8%, respectively while those of potyviruses including Zucchini yellow mosaic virus, Papaya ringspot virus, and Watermelon mosaic virus were 15.7%, 9.3%, and 5.1%, respectively. Interestingly, Cucumber mosaic virus was hardly detected. About 5.8% of tested samples were infected with more than one virus. Tobamovirus infection was consistently observed from September to December regardless of planting time, whereas infection of potyviruses was observed in many cucumber cultivating areas where it was planted in September and October.