• Journal of Life Science
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• v.23 no.12
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• pp.1415-1419
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• 2013

Electron beam (EB) irradiation was tested to determine the dose required to eradicate plant pathogens, such as Botrytis cinerea and Agrobacterium rhizogenes, from the infected seeds without affecting the germination rate of the irradiated vegetable seeds, including crown daisy, cucumber, hot pepper, green onion, leaf lettuce, and radish seeds. EB irradiation of 1.5 kGy and 2 kGy was sufficient to kill 100% of hairy root disease bacteria and gray mold conidia, respectively. EB irradiation showed no effect or minimal effect on the germination rate of the crown daisy, cucumber, green onion, and radish seeds. However, the germination rate of the hot pepper and leaf lettuce seeds was significantly reduced by using 2 kGy of EB irradiation. Difference in susceptibility to EB irradiation appears not to be related to the weight of each seed, but to the intrinsic characteristic of each plant. Conclusively, EB irradiation might be a useful way to decontaminate crown daisy, cucumber, green onion, and radish seeds.

• The Plant Pathology Journal
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• v.40 no.2
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• pp.125-138
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• 2024

Citrus yellow vein clearing virus (CYVCV) is a member of the Alphaflexiviridae family that causes yellow vein clearing symptoms on citrus leaves. A total of 118 leaf samples from nine regions of six provinces in Korea were collected from various citrus species in 2020 and 2021. Viral diagnosis using next-generation sequencing and reverse transcription polymerase chain reaction (RT-PCR) identified four viruses: citrus tristeza virus, citrus leaf blotch virus, citrus vein enation virus, and CYVCV. A CYVCV incidence of 9.3% was observed in six host plants, including calamansi, kumquat, Persian lime, and Eureka lemon. Among the citrus infected by CYVCV, only three samples showed a single infection; the other showed a mixed infection with other viruses. Eureka lemon and Persian lime exhibited yellow vein clearing, leaf distortion, and water-soak symptom underside of the leaves, while the other hosts showed only yellowing symptoms on the leaves. The complete genome sequences were obtained from five CYVCV isolates. Comparison of the isolates reported from the different geographical regions and hosts revealed the high sequence identity (95.2% to 98.8%). Phylogenetic analysis indicated that all the five isolates from Korea were clustered into same clade but were not distinctly apart from isolates from China, Pakistan, India, and Türkiye. To develop an efficient diagnosis system for the four viruses, a simultaneous detection method was constructed using multiplex RT-PCR. Sensitivity evaluation, simplex RT-PCR, and stability testing were conducted to verify the multiplex RT-PCR system developed in this study. This information will be useful for developing effective disease management strategies for citrus growers in Korea.

• Research in Plant Disease
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• v.16 no.1
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• pp.97-100
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• 2010

Angular leaf spot of strawberry caused by Xanthomonas fragariae occurred sporadically in the farmers open field at Sugok-myon, Jinju city, and greenhouse at Okjong-myon, Hadong-gun, Gyeongnam province, Korea. Typical symptoms of angular leaf spot initially appeared as a minute, water-soaked, rotted lesion on the lower leaf surface and the minute spots expanded to form angular leaf spots, usually delimited by small veins. The lesion was translucent under the transmitted light and dark green under reflected light. The slow growing pathogen was a gram-negative, motile bacterium with single polar flagellum, and producing yellowish orange pigment on YDC medium. It showed very strong pathogenicity on the leaves of strawberry. On the basis of biological characteristics and pathogenicity test on host plants, the bacteria was identified as a Xanthomonas fragariae. This is the first report on angular leaf spot of strawberry caused by X. fragariae in Korea.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.342-346
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• 2001

The physiological changes in sorghum (Sorghum vulgare Pers.) leaves infected with Drechslera sorghicola were investigated through five recognizable stages of disease development. Water-soaked yellowish brown spots developed two days after inoculation, turned brown with yellow halo, enlarged and coalesced at later stages of disease development. Healthy and infected leaves were analyzed for different biochemical constituents. The chlorophyll contents were decreased significantly with the progress of infection. The levels of reducing and total sugars increased while non-reducing sugars decreased to a significant extent with the progress of disease. The concentration of total phenolics, orthodihydroxy phenols, free and glycosidic phenols showed significant changes due to infection, whereas basic and acid phenols showed little or no change with disease development. Levels of phenolic compounds increased four days after inoculation and decrease thereafter, but the concentration was higher at every stage of disease development relative to healthy tissues. Polyphenol oxidase and peroxidase enzyme activities increased to varying degrees at different stages of infection. Analysis of protein fractions showed a significant increase with the progress of disease.

• Korean Journal Plant Pathology
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• v.12 no.2
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• pp.209-213
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• 1996

배나무잎 이상반점증상의 발병환경 조건을 조사하고자 실험한 결과 주간 23$^{\circ}C$, 야간 18$^{\circ}C$ 온도조건에서 병징발현이 가장 심하였고 이보다 높은 온도인 28/23$^{\circ}C$와 낮은 온도인 18/13$^{\circ}C$에서는 발병이 아주 적었다. 배나무잎에 봉지를 피복하면 발병이 전혀 없거나 극히 저조하였다. 이것은 봉지내의 온도가 최고 46.8$^{\circ}C$까지 올라가 고온에 의하여 발병이 억제된 것으로 생각된다. 이병주 토양과 건전주 토양의 화학성을 조사한 결과 이병주 토양에서는 건전주 토양보다 유효인산량이 많게 나타났다. 토양수분이 많거나 적었을 때는 병징발현이 다소 늦어지기는 하나 최종 조사시 발병정도는 큰 차이를 나타내지 않았다.

• Korean Journal Plant Pathology
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• v.12 no.3
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• pp.368-373
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• 1996

배나무잎 검은점병에 이병된 신고와 지표식물 PS-95의 잎을 전자현미경으로 세포내 미세구조를 검경한 결과 굴곡성 사상형 유사바이러스 입자가 집단으로 존재하고 있는 것을 확인하였다. 엽육유세포질에 있는 유사바이러스 입자들의 직경은 12 nm였으나 입자들의 길이는 측정하지 못하였다. 섬유사를 함유하고 있는 소포는 일반적으로 ssRNA genome을 갖는 식물바이러스에 의해 이병된 세포에서 생성된다. 본 연구에서 이 소포들은 tonoplast에 형성되었다. 배나무잎 검정점병의 이병잎을 초본 지표식물에 즙액접종하였으나 어떠한 병징도 나타나지 않았다. 또한 접목접종 전염에 의하여 전염되어 전형적인 검은점이 발병하였다. 발병된 잎에는 유사바이러스 입자가 존재하고 있었다. 이상의 결과 병징, 섬유사를 함유한 소포의 존재, 그리고 접목전염을 기초로하여 볼 때 배나무 검은점병을 일으키는 유사바이러스 입자는 closteroviruses의 하나로 생각된다.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.496-501
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• 1998

Incidence of rice blast on new rice cultivars and elite lines was observed from 1995 to 1997 in Icheon, Chuncheon, Jecheon and Naju areas. The observation was made in the nurseries and fields. In the nurseries, three cultivars Grubyeo, Sangjuchalbyeo and Suwon 414 showed moderate levels of resistance to leaf blast, with the disease index 0 to 5. From the field observation, it was found that cultivars Heugjinjubyeo and Unbong 18 were highly resistant to leaf blast, but susceptible to neck blast. In general, there was a great variation yearly and regionally in the incidence of neck blast within the same cultivar, ranging from 0 to 100%. However, the range of neck blast infection was relatively narrower in the cultivars Yunghaebyeo (0∼2.4%) and Suwon 414 (0∼2.2%) during observation period. Races of rice blast fungus were variable at different areas. Among them dominant races were KI-409, KJ-201 and KJ-301.

• Journal of Ginseng Research
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• v.46 no.6
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• pp.790-800
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• 2022

Background: Panax ginseng Meyer is one of the most valuable medicinal plants which is enriched in anti-microbe secondary metabolites and widely used in traditional medicine. Botrytis cinerea is a necrotrophic fungus that causes gray mold disease in a broad range of hosts. B. cinerea could overcome the ginseng defense and cause serious leaf and root diseases with unknown mechanism. Methods: We conducted simultaneous transcriptomic and metabolomic analysis of the host to investigate the defense response of ginseng affected by B. cinerea. The gene deletion and replacement were then performed to study the pathogenic gene in B. cinerea during ginseng - fungi interaction. Results: Upon B. cinerea infection, ginseng defense responses were switched from the activation to repression, thus the expression of many defense genes decreased and the biosynthesis of antifungal metabolites were reduced. Particularly, ginseng metabolites like kaempferol, quercetin and luteolin which could inhibit fungi growth were decreased after B. cinerea infection. B. cinerea quercetin dioxygenase (Qdo) involved in catalyzing flavonoids degradation and ∆BcQdo mutants showed increased substrates accumulation and reduced disease development. Conclusion: This work indicates the flavonoids play a role in ginseng defense and BcQdo involves in B. cinerea virulence towards the P. ginseng. B. cinerea promotes disease development in ginseng by suppressing of defense related genes expression and reduction of antifungal metabolites biosynthesis.

• Korean Journal of Medicinal Crop Science
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• v.9 no.2
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• pp.150-155
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• 2001

This experiment was carried out to investigate the effect of rain shelter cultivation on growth characteristic and yield on Paeonia lactiflora Pallas. The sprouting time and flowering time of rain shelter cultivation were 9days and 15days, more quickly than that of field conditions, and stem length and number of stem per plant were many more or larger. The disease occurrence rain shelter cultivation was decreased of rust, anthracnose, powdery mildew and root rot disease compared to field conditions, and leaf spot disease was to similar. The root length, number of root and root diameter were to be good in the rain shelter cultivation. Root color and commercial ratio of rain shelter cultivation were better lighten and improved than field cultivation. Root yield of rain shelter was 2,395kg/10a, this was increased 9% and 27% respectively, compared to 2,201kg/10a, 1,892kg/10a of field A and field B.

• Research in Plant Disease
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• v.12 no.1
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• pp.10-14
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• 2006

This study was carried out to know damages of the grapevine trees by the disease to the leaf spot from 2000 to 2003. The isolates collected from different varieties and locations were identified as Pseudocercospora vitis ($(L\acute{e}v)$.) Speg. based on the morphological and cultural characteristics. According to the in vitro test, the range of temperatures for the mycerial growth and the conidical germination of the fungus were from $10^{\circ}C\;to\;35^{\circ}C$ and optimum temperature was $25^{\circ}C$. There were remarkably different features between a low infection trees group and high infection trees group in terms of number of leaves per fruit branch, length and diameter of internode and leaf area.