• The Plant Pathology Journal
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• v.27 no.4
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• pp.372-377
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• 2011

A virus causing mottle and stunt symptom on Zea mays was observed around Ulleng-do, Korea and identified as Cucumber mosaic virus (CMV-ZM) based upon biological, serological, and molecular characteristics. In host range studies, the CMV-ZM isolate produced local lesions on Datura stramonium, Vigna unguiculata, Cucurbita moschata, Chenopodium amaranticolor, Ch. quinoa, whereas this isolate produced systemic mosaic on Nicotiana tabacum cv. 'Xanthi-nc', Capsicum annuum, Solanum lycopersicum, Solanum melongena, Cucurbita pepo, and Z. mays. In addition, chlorotic local rings on inoculated leaves along with severe mosaic, malformation, and fern leaf symptoms on upper systemic leaves were shown in N. glutinosa plants. Complete nucleotide sequences of each genomic RNA segment was determined and compared to those of the other CMV strains. Comparison of the nucleotide sequence of 1a open reading frame (ORF) revealed approximately 89.2-92.4% sequence identity with each CMV subgroup IA and IB strain, while showing only 78% sequence identity with CMV subgroup II. Nucleotide sequence analysis of RNA2 ORFs revealed 85.3-97.6% sequence identity with subgroup I. In ORFs of RNA3, levels of nucleotide sequence identities were higher than 92-99.2% with CMV subgroup I and lower than 82% with CMV isolates of subgroup II. These results suggest that CMV-ZM isolate is more closely related to subgroup I than subgroup II and therefore, CMV-ZM isolate might be classified into as CMV subgroup I based on biological and molecular analysis.

• Research in Plant Disease
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• v.17 no.3
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• pp.364-368
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• 2011

Gray mold caused by Botrytis cinerea was found on a carrot seedling in a greenhouse and a field at Daegwallryeong, Gangwon Province in 2007-2009. Symptoms included irregular, brown, blight, or chlorotic halo on leaves and petioles of the carrots. Fungal conidia were globose to subglobose or ellipsoid, hyaline or pale brown, nonseptate, one celled, $7.2-18.2{\times}4.5-11\;{\mu}m$ ($12.1{\times}8.3\;{\mu}m$) in size, and were formed on botryose heads. B. cinerea colonies were hyaline on PDA, and then turned gray and later changed dark gray or brown when spores appeared. The fungal growth stopped at $35^{\circ}C$, temperature range for proper growth was $15-25^{\circ}C$ on MEA and PDA. Carrots inoculated with $1{\times}10^5$ ml conidial suspension were incubated in a moist chamber at $25{\pm}1^{\circ}C$ for pathogenicity testing. Symptoms included irregular, brown, water-soaked rot on carrot roots and irregular, pale brown or dark brown, water-soaked rot on leaves. Symptoms were similar to the original symptoms under natural conditions. The pathogen was reisolated from diseased leaves, sliced roots, and whole roots after inoculation. As a result, this is the first report of carrot gray mold caused by B. cinerea in Korea.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.416-424
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• 2014

Sweet potato is grown extensively from tropical to temperate regions and is an important food crop worldwide. In this study, we established detection methods for 17 major sweet potato viruses using single and multiplex RT-PCR assays. To investigate the current incidence of viral diseases, we collected 154 samples of various sweet potato cultivars showing virus-like symptoms from 40 fields in 10 Korean regions, and analyzed them by RT-PCR using specific primers for each of the 17 viruses. Of the 17 possible viruses, we detected eight in our samples. Sweet potato feathery mottle virus (SPFMV) and sweet potato virus C (SPVC) were most commonly detected, infecting approximately 87% and 85% of samples, respectively. Furthermore, Sweet potato symptomless virus 1 (SPSMV-1), Sweet potato virus G (SPVG), Sweet potato leaf curl virus (SPLCV), Sweet potato virus 2 ( SPV2), Sweet potato chlorotic fleck virus (SPCFV), and Sweet potato latent virus (SPLV) were detected in 67%, 58%, 47%, 41%, 31%, and 20% of samples, respectively. This study presents the first documented occurrence of four viruses (SPVC, SPV2, SPCFV, and SPSMV-1) in Korea. Based on the results of our survey, we developed multiplex RT-PCR assays for simple and simultaneous detection of the eight sweet potato viruses we recorded.

• Research in Plant Disease
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• v.18 no.3
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• pp.255-258
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• 2012

In September 2011, black leaf mold caused by Pseudocercospora fuligena occurred on tomato plants growing in protected cultivation conditions in Boryong and Buyeo, Chungnam Province, Korea. Symptoms of the disease initially appeared as foliar chlorotic spots on upper leaf surfaces, turned light brown and then black on lower leaf surfaces as the fungus sporulates profusely. The causal fungus was isolated from the diseased plants and identified as P. fuligena based on morphological characteristics. Pathogenicity of the fungus was proved by artificial inoculation in the green house. This is the first report of the occurrence of black leaf mold of tomato caused by P. fuligena in Korea.

• Research in Plant Disease
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• v.19 no.4
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• pp.313-318
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• 2013

In March, 2013, twenty symptomatic freesia plants (10 plants of cultivar Shiny Lemon and 10 plants of cultivar Shiny Gold), with striking virus-like symptoms were collected in Cheongju, Korea. The plants showed chlorotic, coalescing, interveinal, whitish, necrotic, mosaic, mottling or dark brown-to-purple necrotic spots on leaves. Freesia crude sap was directly analyzed by transmission electron microscopy, which potyvirus particles as well as long virus-like particles were detected. Total RNA extracts were analyzed for the infection of Freesia sneak virus (FreSV) by reverse transcription (RT)-PCR with primers specific to FreSV coat protein (CP) gene based on the sequences of FreSV isolates (GenBank No. GU071089, FJ807730 and DQ885455), showing 9 of 20 plants were infected. All 1305bp RT-PCR products were cloned and sequenced. Comparisons of nucleotide and deduced amino acid sequences using BLAST and bioinformatics tools resulted in 99 to 100% sequence identity with FreSV isolates FOV, Virginia, and Italy, confirming FreSV in 9 symptomatic freesia plants. Of 9 determined cDNAs of FreSV isolates, sequences of 5 cDNA clones were identical (GenBank No. AB811437) and sequences of 4 cDNA clones were identical (GenBank No. AB811792). To our knowledge, this is the first report of FreSV from Freesia spp. in Korea.

• 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.

• Research in Plant Disease
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• v.14 no.2
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• pp.134-137
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• 2008

A strain of Cucumber mosaic virus(CMV) was isolated newly from sweet pepper(Capsicum annuum var. angulosum) showing necrosis with large necrotic spots on fruits and vein banding with malformation on leaf at Cheongdo area in Gyeongsangbukdo. The new strain was designated as a CMV-NP and the shape of virus particles was isometric of 26 nm in diameter from the sweet pepper fruit by Dip method. The strain of CMV-NP was identified genetically by VC/RT-PCR. CMV-NP could infect systemically on the 9 indicator plants including Cucumis sativus, but it could infect locally on Chenopodim amaranticolor and C. quinoa. CMV-NP induced the specific symptoms of necrotic rings on the inoculated and the upper leaves of N. rustica and Tetragonia expansa. On Cucumis sativus, the large chlorotic ring and vein chlorosis were produced on the upper leaves. CMV-NP had no virulence on Datura stramonium.

• Research in Plant Disease
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• v.10 no.2
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• pp.126-129
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• 2004

In July of 2002, leaf spot disease was found on kudzu (Pueraria lobata) leaves in Jeonbuk province. A small leaf spot was appeared on leaves as a typical symptom and the spot was then surrounded by chlorotic halo. The lesions were expended and coalesced and the infected leaves became yellow leaf and later fall out. A causal fungal pathogen was isolated and the colony of the pathogen was light gray green to dark green on PDA. The pathogen produced mostly the single conidium but rarely long chain of 3 to 8 conidia. The conidia were dark brown in color, long ellipsoid or oval and 20-60 ${\times}$ 10-25 ${\mu}{\textrm}{m}$ in size. Their septa were 4-8 transverse and 1-2 longitudinal or oblique. The pathogen was, therefore, identified as Alternaria tenuissima based on cultural and morphological characteristics. This is the first report on the leaf spot of kudzu caused by A. tenuissima in Korea.

• Korean Journal Plant Pathology
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• v.2 no.1
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• pp.48-52
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• 1986

The virus isolated from white clover, Trifolium repens showing mosaic symptom was identified as bean yellow mosaic virus (BYMV) based on the host range, physical properties, aphid transmission, serology and morphology of the virus particles. Chenopodium amaranticolor and C. quinoa produced local lesions on the inoculated leaves and chlorotic spot on the upper leaves. Broad bean and cowpea produced local lesions on the inoculated leaves and mosaic with vein necrotic symptoms on the upper leaves. French bean showed vein necrosis on the inoculated leaves, yellow mosaic on the upper leaves and bud blight. The average size of virus particles was 740nm in length. The virus was also transmitted by Myzus persicae. The thermal inactivation point of the virus isolate was $60\;to\;65^{\circ}C$, the dilution end point $10^{-3}\;-\;10^{-4}$ and the longevity in vitro was 3 days Serological tests with the virus purified from Trifolium repens were positive to BYMV antiserum.

• Research in Plant Disease
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• v.24 no.1
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• pp.81-85
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• 2018

Chinese artichoke (Stachys sieboldii Miq.) belongs to herbaceous perennial plants of Labiatea and is cultivated as edible and medicinal crops in China, Japan and Korea. A Chinese artichoke plant showing virus-like symptoms was collected in Chungju, Korea. Plant sap of the sample was inoculated in Nicotiana tabacum cv. Xanthi-nc, Chenopodium quinoa and Chenopodium amaranticolor. Necrotic local lesions were observed in the inoculated leaves of N. tabacum cv. Xanthi-nc and C. amaranticolor, C. quinoa with systemic chlorotic spots and mosaic symptoms on the upper leaves. The disease reactions on indicator plants suggested that the collected Chinese artichoke sample was mixed-infected with different viruses. We detected three viruses by RT-PCR analysis using genus- and species-specific primer sets for Alfalfa mosaic virus (AMV), Cucumber mosaic virus (CMV) and Tobacco mosaic virus (TMV). This study is the first report of a mixed infection of three viruses in Chinese artichoke in Korea.