• The Plant Pathology Journal
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• v.34 no.3
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• pp.199-207
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• 2018

Tomato chlorosis virus (ToCV) is a whitefly-transmitted and phloem-limited crinivirus. In 2013, severe interveinal chlorosis and bronzing on tomato leaves, known symptoms of ToCV infection, were observed in greenhouses in Korea. To identify ToCV infection in symptomatic tomato plants, RT-PCR with ToCV-specific primers was performed on leaf samples collected from 11 tomato cultivating areas where ToCV-like symptoms were observed in 2013 and 2014. About half of samples (45.18%) were confirmed as ToCV-infected, and the complete genome of 10 different isolates were characterized. This is the first report of ToCV occurring in Korea. The phylogenetic relationship and genetic variation among ToCV isolates from Korea and other countries were also analysed. When RNA1 and RNA2 are analysed separately, ToCV isolates were clustered into three groups in phylogenetic trees, and ToCV Korean isolates were confirmed to belong to two groups, which were geographically separated. These results suggested that Korean ToCV isolates originated from two independent origins. However, the RNA1 and RNA2 sequences of the Yeonggwang isolate were confirmed to belong to different groups, which indicated that ToCV RNA1 and RNA2 originated from two different origins and were reassorted in Yeonggwang, which is the intermediate point of two geographically separated groups.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.36-45
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• 2008

Studies with the transmission electron microscope were used to detect and attempt to identify viruses infecting sweetpotato (Ipomoea batatas) and other Ipomoea species. Flexuous-rods, short curved-rods, and spherical virus-like particles were observed in cells of symptomatic plants. Also, various cytopathic changes such as crystals, vesicles, fibril structures, and cylindrical inclusions were observed. The present study showed that some of these cytopathic changes were associated with some viral groups, which might be helpful in diagnosis.

• The Plant Pathology Journal
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• v.33 no.3
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• pp.345-349
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• 2017

Tomato chlorosis virus (ToCV), a member of the genus Crinivirus, has caused an epidemic disease in tomato worldwide. ToCV is phloem-limited and transmitted by whiteflies in a semi-persistent manner, but not by mechanical inoculation. Experimental propagation of ToCV has been performed primarily by using whitefly-mediated inoculation. To develop a simple and convenient method for transmission of ToCV, we investigated grafting single-leaflets from tomato plants infected with ToCV to recipient tomato seedlings. Forty-one of 46 tomato seedlings tested were grafted successfully with single-leaflets infected with ToCV. Among them, 36 seedlings (87.8%) were systemically infected with ToCV and developed typical symptoms. Our results demonstrated that single-leaflet grafting could provide a sufficient amount of inoculum for the transmission of ToCV to the grafted seedlings.

• Research in Plant Disease
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• v.29 no.1
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• pp.52-59
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• 2023

Cucurbit chlorotic yellows virus (CCYV) is a plant virus that causes damage to cucurbit crops such as watermelon and cucumber, and is transmitted by an insect vector known as the whitefly. Since CCYV was first detected on cucumber in Chungbuk in 2018, it has been reported in other areas including Gyeongsang in Korea. In 2020, we performed field surveys of yellowing diseases in the greenhouses growing melon and watermelon in Chungbuk (Jincheon and Eumseong). Reverse transcription-polymerase chain reaction analysis of 79 collected samples including melon, watermelon, and weeds resulted in detection of CCYV in 4 samples: Three samples were singly infected with CCYV and one samples was mixed infected with CCYV, Cucurbit aphid borne yellows virus, and Watermelon mosaic virus. The complete genome sequences of the four collected CCYV melon isolates (ES 1-ES 4) were determined and genetically compared with those of previously reported CCYV isolates retrieved from GenBank. Phylogenetic analyses of RNA 1 and 2 sequences revealed that four ES isolates were clustered in one group and closely related to the CCYV isolates from China. The analysis also revealed very low genetic diversity among the CCYV ES isolates. In general, CCYV isolates showed little genetic diversity, regardless of host or geographic origins. CCYV has the potential to pose a serious threat to melon, watermelon, and cucumber production in Korea. Further studies are needed to examine the pathogenicity and transmissibility of CCYV in weeds and other cucurbits including watermelon.