• Research in Plant Disease
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• v.21 no.2
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• pp.103-106
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• 2015

Isolates of the rice blast fungus show a range of tissue-specificities infecting leaves, nodes, neck and panicles. Although neck and panicle blast cause significantly greater yield losses than the leaf blast, virulence tests of the blast isolates have been performed only rice leaves instead of neck and panicles. In this study, we have developed a virulence test method for neck and panicle blast. We selected three representative isolates from each of leaf, neck, and panicle blast. We observed that severe disease lesions developed on the neck and the panicles when the infected rice plants were incubated in a dew chamber for 48 h instead of 24 h when tested on leaves. Unlike the leaf blast, a typical lesion on the neck and panicles appeared after 14 days post-infection as opposed to 7 days with leaf blast. This method will be applied to examine tissue-specificity of the rice blast fungus isolates.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.47-53
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• 1994

Incidences of blast caused by Pyricularia grisea Sacc. on 24 leading cultivars and elite lines of rice were investigated in the fields at Icheon, chuncheon, Jecheon, Naju from 1990 to 1992. In the blast nursery, disease index of leaf blast on Jinmibyeo and Ilpumbyeo were very low as 1 to 3 at Naju, but as high as 6 to 9 at Icheon and other Chuncheon in 1990, but the disease did not occur in other locations and years. The most variable incidence of temporal and spatial leaf blast was observed on Nagdongbyeo, which was 30.6% at Icheon and 2.1% at Chuncheon on 1990, but the disease did not occur at Naju during the investigation. Percentages of diseased panicles on Chucheongbyeo were 11.6% in 1990 and 4.3% in 1992 at Icheon. Odaebyeo and Sobaekbyeo revealed more severe blast occurrences at Chuncheon and Sangju where the elevation was higher than the other places. Regional race distributions of rice blast fungus were more variable at Icheon and Chuncheon than the others.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2004.10a
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• pp.61-62
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• 2004

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• Korean Journal Plant Pathology
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• v.13 no.2
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• pp.90-94
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• 1997

Interaction of races of rice blast fungus and cultivars has been evaluated. Dongjinbyeo was infected by four KJ races and two KI races, while other varieties were susceptible to four to six KJ or KI races. Among the single spores reisolated from the leaf blast lesion of Dongjinbyeo after mixed inoculation of 10 races, 63% was race KJ-301 which produced a small number and small size lesions, while 30% was race KI-313 which produced a large number of lesions. However, 93% of single spores reisolated from Palgongbyeo was a highly virulent race KJ-105. On the other hand, all the races were equally reisolated from the susceptible cultivar Jinmibyeo. Frequency of races isolated from the naturally infected leaf blast lesions in the field was similar to that of reisolated races from the cultivars inoculated with 10 mixed races in the greenhouse. However, 30% of single spores isolated from the naturally infected Dongjinbyeo was race KI-329 ut ace KI-313 was not detected. Genetic relationship of the isolates collected from leaf and neck blast fungus of Jinmibyeo and Nakdongbyeo showed specific bands on RFLP-P64, However, their genetic similarity was 80%.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.705-709
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• 1998

Temporal and spatial distribution of Korean rice blast fungus (Pyricularia grisea) race KI-409 that has been rapidely increased since 1993 and became predominant in 1995 in Korea were investigated. Varietal resistance of current commercial cultivars of rice to the race was also tested in this study. The race KI-409 was first isolated from rice cv. Namyangbyeo in 1985. Since 1985 the race had been isolated mainly from the rice cultivars having BL1 BL7 pedigree as a resistance source. Distribution ratio of the race in 1995 was 23.7% in average and became a predominant in the P. grisea population in Korea. The race distributed widely and found in all the eight provinces in Korea. Many commercial cultivars such as Chucheongbyeo as well as those with BL1 or BL7 as a genetic background were found to be susceptible to the race KI-409.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.1026-1028
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• 2002

Screening tests against fungus causing rice blast, Magnaporthe grisea, were performed in order to develop biopesticides. More than 400 actinomycetes collected at several sites near Hanla Mountain on Jeju Island, Korea were tested, and strain BG2-53 showed potent antifungal activity. The in vivo screening was performed with fermentation broth, and the strain taxon was identified.

• Korean Journal Plant Pathology
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• v.13 no.2
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• pp.79-84
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• 1997

Incidence of rice blast on new rice cultivars and elite lines was observed from 194 to 1996 in Icheon, Chuncheon, Jecheon and Naju areas. The observations were made in the nuseries and in the fields. In the nurseries, only cultivars Daesanbyeo and Hyangmibyeo 2 showed moderate levels of resistance to leaf blast, with the disease index 0 to 6. From the field observations, it was found that cultivars Hyangmibyeo 2 and Suwon 414 were highly resistant to leaf blast, but susceptible to neck blast. the fields, leaf blast was not observed. In general, there was great yearly and regional variation in the incidence of neck blast within the same cultivars, some times ranging from 0 to 100% of incidence. However, the range of fluctuation in the disease incidence were relatively small in the cultivars Daejinbyeo (0∼17.5%), Daesanbyeo (0∼4.0%), Donganbyeo (0∼21.4%) and Hwasambyeo (0∼13.9%). Hyangmibyeo 2 and Seojinbyeo were rarely infected with neck blast in Chuncheon and Naju all of the years, the same cultivars were severely infested with neck blast; 45.1 and 45.5%, respectively, in Jecheon in 1995. The occurrence of different races of rice blast fungus were different at different areas. However, it was found that in Icheon, Chuncheon, Jecheon and Naju areas, the dominant races were KI-409, KJ-201 and KJ-301.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.123-128
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• 1994

Incidence of blast caused by Pyricularia grisea Sacc. on 21 leading cultivars and elite lines of rice was investigated in different locations such as Icheon, Chuncheon, Jecheon, and Naju during three years from 1991 to 1993. Disease index of leaf blast of Dongjinbyeo was high in the blast nursery with range 4 to 9 at Naju, but low at other locations with range 1 to 4. Percentages of diseased leaf area of Joryungbyeo and Daelipbyeo 1 were 4.3 and 12%, respectively in the fields at Jecheon in 1993, but were much lower in the other locations during three years. The incidences of leaf blast of Daelipbyeo 1 were 0.3 and 12.0% at Chuncheon and Jecheon, respectively in 1993, but no disease occurred at Naju during three years. Percentage of diseased panicles of Joryungbyeo was 100% at Icheon and Jecheon in 1993, 92.4% in Suweon 390 at Icheon on 1991 and 100% in Jinbu 15 at Jecheon on 1993. Race distribution of rice blast fungus at Icheon and Jecheon was more varied than that of the other locations.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.134-134
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• 2017

Recently, host-induced gene silencing (HIGS) system has been successfully applied into development of resistant crops against insects, fungal and viral pathogens. To test HIGS-mediated resistance in rice against rice blast fungus, Magnaporthe oryzae, we first tested possibility of movement of small non-coding RNA from rice cells to rice blast fungus. The rice blast fungus expressing GFP transgene were inoculated to transgenic rice plants ectopically expressing dsRNAi construct targeting fungal GFP gene. Expression of dsRNAi construct for GFP gene in transgenic plants significantly suppressed GFP expression in infected fungal cells indicating that small RNAs generated in plant cells can move into infected fungal cells and efficiently suppress the expression of fungal GFP gene. Consistent with these results, expression of dsRNAi constructs against 3 fungal pathogenic genes of M. oryzae in transgenic rice specifically and efficiently suppressed not only the expression of fungal pathogenic genes, but also fungal infection. The conidia of M. oryzae applied on leaf sheath of transgenic rice expressing dsRNAs against 3 fungal pathogenic genes showed abnormal development of primary hyphae and malfunction of appressorium, which is consistent with the phenotypes of corresponding fungal knock-out mutants. Taken these results together, here, we suggest a novel strategy for development of antifungal crops by means of HIGS system.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.78-82
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• 1994

Unusually severe rice blast epidemic sweeped over the rice growing area in Gyeongnam Province and elsewhere in 1993. Leaf blast infection was reached to 33,133 ha, which is about 24.5% of total paddy area and neck blast infection was apparent throughout 4,421 ha. Major factors affecting such an unusual epidemic appeared to be as follow: Firstly, low temperature, frequent rainfall and coincidentally insufficient duration of sunshine through July and August; Secondly, most cultivars possessing low levels of field resistance were cultivated in wide areas: Thirdly, blast fungus population was enough for successive infection under optimum weather condition and most races distributed in field were able to infect most cultivars.