• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.281-287
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• 2013

In Korea, isolated cultivation has been implemented for 102 genera, including about 250 species, each of which has underwent microscopic inspection, cultivation of bacteria in selective medium, analysis of physiology and biochemistry, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). The number of isolated microorganisms was 8,307 in the period of 2005-2012, and bulbs and tubers had the greatest diversity of microorganisms, of 5,165 (62.2%), followed by 2,119 (25.0%) sapling, 796 (9.6%) seed, 150 (1.8%) cutting slip, 70 (0.8%) branch graft and 7 (0.1%). The number of cases which were disqualified were 413 (4.97%), after the detection of 47 disease causing species of microorganism. Viruses predominated, with 27 species, followed by 16 fungi, a viroid, a Chromalveolata and 2 further species. Top on the list of detection was Arabis mosaic virus (77 cases), followed by Tobacco rattle virus (70 cases), Lily symptomless virus (46 cases) and Penicillium expansum (46 cases).

• Research in Plant Disease
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• v.23 no.1
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• pp.65-68
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• 2017

Barley yellow mosaic virus (BaYMV), which is transmitted by the root-inhabiting protist Polymyxa graminis, causes a soil-borne disease. In this study, we detected BaYMV from soil using two-step nested polymerase chain reaction (PCR). Specific primers based on a coat protein region of BaYMV segment RNA1 were used in the first round of amplification. Based on the sequenced amplicon, an inner primer was designed for the second round of amplification. A PCR product of 372 bp exhibited 98%-100% nucleotide sequence identity with the coat protein region of BaYMV segment RNA1. In this study, we propose an easy method for the detection of BaYMV from soil, may considerably assist in accurate fungus-transmitted virus diagnosis and subsequent disease forecasting. This is the first report on the detection of BaYMV from soil.

• Research in Plant Disease
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• v.16 no.1
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• pp.1-9
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• 2010

Among the plant specimens requested from agricultural actual places of farmers, Agency of agricultural extension services and so forth for the diagnosis of plant virus diseases in 2009, the rate of crop types was 87.5% for vegetables, 4.0% for upland crops and 3.5% for orchids. In vegetables, the crops damaged severely by viral diseases were red pepper and tomato by the infection rate of 51.6% and 26.5%, orderly. Virus species occurring vegetables were 19 and the economically important viruses were Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV), Tomato yellow leaf curl virus (TYLCV), Pepper mild mottle virus (PMMoV) with the infection rate of 33.2%, 16.9%, 16.1% and 7.4%, respectively. Rice stripe virus (RSV) occurred at the whole areas of west coast in Korea in 2009, and its incidence was 14.2% mainly on the susceptible cultivars and yield loss was estimated up to 50%. TYLCV was spread at 34 areas of Si and/or Gun, 22 areas in 2009 and 12 in 2008. Distribution of TSWV was expanded newly in 6 areas of Si and/or Gun including Gangryung, Gangwondo in 2009, and its occurrence areas were 23 Si and/or Gun after first incidence at Anyang area in 2004. Tomato bushy stunt virus (TBSV) was incited newly at Gimcheon area in 2009 with the infection rate of 65.2%, and its soil transmission rate was 55.0% in average.

• Research in Plant Disease
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• v.11 no.2
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• pp.98-105
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• 2005

All viruses have few genes relative to their hosts. Viruses, thus, utilize many host factors for efficient viral replication in host cell. Virus-host interactions are crucial determinations of host range, replication, and pathology. Host factors participate in most steps of positive-strand RNA virus infection, including entry, viral gene expression, virion assembly, and release. Recent data show that host factors play important roles in assembling the viral RNA replication complex, selecting and recruiting viral RNA replication templates, activating the viral complex for RNA synthesis, and the other steps. These virus-host interactions may contribute to the host specificity and/or pathology. Positive-strand RNA viruses encompass over two-thirds of all virus genera and include numerous pathogens. This review focuses on the importance of host factors involved in positive strand plant RNA virus genome replication.

• 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.

• Korean Journal Plant Pathology
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• v.14 no.2
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• pp.150-156
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• 1998

To develop a model for prediction of turnip mosaic virus(TuMV) disease progress of Chinese cabbage based on weather information and number of TuMV vector aphids trapped in Taegwallyeong alpine area, data were statistically processed together. As the variables influenced on TuMV disease progress, cumulative portion(CPT) above 13$^{\circ}C$ in daily average temperature was the most significant, and solar radiation, duration of sunshine, vector aphids and cumulative temperature above $0^{\circ}C$ were significant. When logistic model and Gompertz model were compared by detemining goodness of fit for TuMV disease progress using CPT as independent variable, regression coefficient was higher in the logistic model than in the Gompertz model. Epidemic parameters, apparent infection rate and initial value of logistic model, were estimated by examining the relationship between disease proportion linearized by logit transformation equation, In(Y/Yf-Y) and CPT. Models able to describe the progression of TuMV disease were formulated in Y=100/(1+128.4 exp(-0.013.CPT.(-1(1/(1+66.7.exp(-0.11.day). Calculated disease progress from the model was in good agreement with investigated actual disease progress showing high significance of the coefficient of determination with 0.710.

• The Plant Pathology Journal
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• v.37 no.4
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• pp.375-388
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• 2021

Rice yellow mottle virus (RYMV) is the most harmful virus that affects irrigated and lowland rice in Africa. The RBe24 isolate of the virus is the most pathogenic strain in Benin. A total of 79 genotypes including susceptible IR64 (Oryza sativa) and the resistant TOG5681 (O. glaberrima) as checks were screened for their reactions to RBe24 isolate of RYMV and the effects of silicon on the response of host plants to the virus investigated. The experiment was a three-factor factorial consisting of genotypes, inoculation level (inoculated vs. non-inoculated), and silicon dose (0, 5, and 10 g/plant) applied as CaSiO₃ with two replications and carried out twice in the screen house. Significant differences were observed among the rice genotypes. Fifteen highly resistant and eight resistant genotypes were identified, and these were mainly O. glaberrima. Silicon application did not affect disease incidence and severity at 21 and 42 days after inoculation (DAI); it, however, significantly increased plant height of inoculated (3.6% for 5 g CaSiO₃/plant and 6.3% for 10 g CaSiO₃/plant) and non-inoculated (1.9% for 5 g CaSiO₃/plant and 4.9% for 10 g CaSiO₃/plant) plants at 42 DAI, with a reduction in the number of tillers (12.3% for both 5 and 10 g CaSiO₃/plant) and leaves (26.8% for 5 g CaSiO₃/plant and 28% for 10 g CaSiO₃/plant) under both inoculation treatments. Our results confirm O. glaberrima germplasm as an important source of resistance to RYMV, and critical in developing a comprehensive strategy for the control of RYMV in West Africa.

• Research in Plant Disease
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• v.10 no.1
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• pp.39-43
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• 2004

Recent occurrence of virus diseases on watermelon plants cultivated in Jeonnam province was investigated from 1998 to 2002. While virus diseases were severely occurred on watermelon cultivated in green house in 1998, those of open field were severer than in green house since 2000. When 128 samples collected from different fields were examined by electron microscopy, 87.8％ of the samples contained rod-shaped or filamentous virus particles. RT-PCR analysis of the samples revealed that Cucumber green mottle mosaic virus (CGMMV) was only detected from collected samples at May. Watermelon mosaic virus (WMV) was most frequently found and CGMMV and Zucchini yellow mosaic virus (ZYMV) were slightly at June and July. However Cucumber mosaic virus (CMV) and Papaya ringspot virus (PRSV) have not been detected.

• The Plant Pathology Journal
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• v.18 no.5
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• pp.237-243
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• 2002

A survey of virus infection in garlic plants cultivated in Korea was conducted for three years. Most virus-infected garlic plants (Allium sativum) showed typical symptoms on the leaves such as yellow mosaic, stripes, and distortion. Through immunosorbent electron micro-scopy and RT-PCR analysis, the complex mixtures of viruses including garlic viruses of the genus Allerivirus, gaylic strain of Leek yellow stripe virus of the genus Potyvirus, and Garlic latent virus of the genus Carlavirus were identified in the virus-infected garlic plants. Among these viruses, Allexivirus was the most frequently detect-ed in the regions surveyed. Using sets of differential primers for Allexivirus genomes, two members of the genus were amplified and sequenced from the purified viruses. The deduced amino acid sequences for the coat proteins and the nucleic acid binding proteins of two viruses showed high homologies to Garlic virus A (CarV-A) and Garlic virus D (GarV-D) of Allekivirus. This is the first report of GarV-A and GarV-D in Korea. This suggests that Allexivirus in gavlic plants in Korea was mixed and varied. Phylogenetic analyses showed that the genus Allexivirus was diversi(ied by the processes of accumulation and evolution of viruses in garlic plants due to the long period of repeated vegetative propagation.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.267-279
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• 2020

Fig mosaic is a viral disease (FMD) that spreads in Palestinian common fig (Ficus carica L.) orchards. Recognizing the economic value of fig plants and the harmful nature of FMD, the disease poses a significant threat to the economy of the fig production in Palestine. We applied the reverse transcription and amplification (RT-PCR) and PCR technique to leaf samples of 77 trees and 14 seedlings of 17 fig cultivars. The samples were collected from orchards in the main fig-growing provinces of the Palestinian West Bank, to assess the prevalence of viruses associated with FMD, and confirm a possible link of symptoms with viruses detected. Four viruses were detected: Fig mosaic virus (FMV), Fig badnavirus-1 (FBV-1), Fig leaf mottle-associated virus 2 (FLMaV-2), and Fig fleck-associated virus (FFkaV). FMV and FBV-1 were found in all tested fig plants (100%), while FLMaV-2 and FFkaV were detected in 61.5% and 33% of the fig samples, respectively. The high incidence of FBV-1 in the newly propagated symptomatic and symptomless seedlings from different cultivars may be an indication that FBV-1 is integrated into the genome of the fig in a cultivar nondiscriminatory manner. Very weak or no association was detected between FMD symptoms severity in the 17 Palestinian fig cultivars with the various viruses' combinations observed (i.e., number of the viruses infecting the plant). These results support the notion that FMD symptom severity expression is likely to be controlled by a combination of FMV infection, cultivars, and environmental factors, rather than the number of viruses infecting the plant.