• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.338-343
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• 1995

Incidence of blast caused by Pyricularia grisea on five new cultivars and four elite lines (C/L) of rice was investigated at different locations, Icheon, Chuncheon, Jecheon and Naju, 1992 to 1994. Disease indices of leaf blast on the tested C/L except Juanbyeo and Keumnambyeo ranged from 0 to 6 in the blast nursery. Under the field conditions, percentages of diseased leaf area of Kuemnambyeo were 6.5% in Jecheon and 2.8% in Icheon in 1993. The incidence of panicle blast on the C/L except Suweon 394 and Milyang 117 differed depending on the locations and years. In case of Unjangbyeo, panicle blast was rarely observed n the fields in Icheon and Naju, but the disease incidences were 21.8% in Jecheon in 1993 and 16.4% in Chuncheon in 1994. Race distribution of the blast fungus was variable according to the locations. The major race in the Jecheon site was KI-197, which was recently identified.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.77-77
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• 2002

• The Plant Pathology Journal
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• v.20 no.4
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• pp.244-246
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• 2004

Sectors of rice blast fungus, Pyricularia grisea, frequently appeared on potato dextrose agar amended with edifenphos and iprobenfos. Thus, we assessed the sector-forming frequency of isolates of P. grisea and compared the fungicide sensitivity between wild types and sectors against the fungicides. The 905 isolates of the fungus were obtained from rice-growing locations in Korea from 1997-1998. When the isolates were grown on potato dextrose agar amended with minimal inhibitory concentrations of edifenphos (20 ${\mu}$g a.i./ml)and iprobenfos (55 ${\mu}$g a.i./ml), they produced sectors that overcame the effect of the fungicides. Among the 905 isolates tested, 9.0% produced sectors against edifenphos and 5.6%, against iprobenfos. Different sector-forming frequencies were also observed among the 11 locations of Korea. Sectors obtained from the fungicide-amended media generally grew more than their counterpart wild types grown on the media with either edifenphos or iprobenfos, regardless of their origins. In this study, greater relative growth of sectors over wild types of tested isolates can support the resistant characteristic of the fungus to survive against the fungicides. Therefore, the results indicate that the sectoring in rice blast fungus, P. grisea, may play a role in the occurrence of fungicide resistance.

• Korean journal of applied entomology
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• v.19 no.1 s.42
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• pp.21-29
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• 1980

In the present study, it was found that the susceptible variety Khao-tah-haeng 17, at all four predisposing temperature regimes, produced more typical lesions than hypersensitive lesions when inoculated with most of the blast fungus isolates. Tetep, Carreon, IR36 and Sensho produced more hypersensitive lesions than typical lesions at all four predisposing temperature regimes. Highly significant differences among predisposing temperature regimes and rice varieties for number of hypersensitive lesions and number of typical lesions were found. Symptom occurrence on a specific variety, as measured by the number of typical lesions, was more affected by predisposition temperature or blast isolate than by temperature and isolate combined. Symptom occurrence on a specific variety, as measured by the number of hypersensitive lesions, was more affected by blast isolate than by predisposition temperature.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.13-13
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• 2015

Rice blast fungus, Magnaporthe oryzae, is the most destructive pathogen of rice in the world. This fungus has a biotrophic phase early in infection and switches to a necrotrophic lifestyle after host cell death. During the biotrophic phase, the fungus competes with host for nutrients and oxygen. Continuous uptake of oxygen is essential for successful establishment of blast disease of this pathogen. Here, we report transcriptional responses of the fungus to oxygen limitation. Transcriptome analysis using RNA-Seq identified 1,047 up-regulated genes in response to hypoxia. Those genes were involved in mycelial development, sterol biosynthesis, and metal ion transport based on hierarchical GO terms and well-conserved among three different fungal species. In addition, null mutants of three hypoxia-responsive genes were generated and tested for their roles on fungal development and pathogenicity. The mutants for a sterol regulatory element-binding protein gene, MoSRE1, and C4 methyl sterol oxidase gene, ERG25, exhibited increased sensitivity to hypoxia-mimetic agent, increased conidiation, and delayed invasive growth within host cells, suggesting important roles in fungal development. However, such defects did not cause any significant decrease in disease severity. The other null mutant for alcohol dehydrogenase gene, MoADH1, showed no defect in the hypoxia-mimic condition and fungal development. Taken together, this comprehensive transcriptional profiling in response to a hypoxia condition with experimental validations would provide new insights on fungal development and pathogenicity in plant pathogenic fungi.

• The Plant Pathology Journal
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• v.37 no.2
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• pp.200-203
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• 2021

Rice blast caused by the filamentous fungus Magnaporthe oryzae, is arguably the most devastating rice disease worldwide. Development of a high-throughput and reliable field blast resistance evaluation system is essential for resistant germplasm screening, resistance genes identification and resistant varieties breeding. However, the occurrence of rice blast in paddy field is easily affected by various factors, particularly lack of sufficient inoculum, which always leads to the non-uniform occurrence and reduced disease severity. Here, we described a procedure for adequately inducing the occurrence of rice seedling blast in paddy field, which involves pretreatment of diseased straw, initiation of seedling blast for the first batch of spreader population, inducing the occurrence of the second batch of spreader population and test materials. This procedure enables uniform and consistent infection, which facilitates efficient and accurate assessment of seedling blast resistance for diverse rice materials.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.61-67
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• 1984

In an attempt to obtain a basic information to develop methods of an effective chemical control and disease forecasting of panicle blast of rice, effects of conidial number of the causal fungus, Pyricularia oryzae, collected in different periods and the rate of leaf blast occurrence on the occurrence of panicle blast were investigated. Conidial number the fungus collected in 5 days before and after heading date were closely related with panicle blast occurrence. But no relationship was obtained between the occurrence rate of leaf blast and that of panicle blast. Considering the incubation period of the disease, we presume that the most effective application periods of chemicals are 5-10 days and 10-15 days before heading, when immediate effective chemicals and slow effective chemicals are applied, respectively.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2004.10a
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• pp.31-32
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• 2004

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• Proceedings of the Microbiological Society of Korea Conference
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• 2009.05a
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• pp.152-153
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• 2009

• The Korea Genome Conference
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• 2005.09a
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• pp.64-64
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• 2005