• The Plant Pathology Journal
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• v.21 no.2
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• pp.87-92
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• 2005

The structural differences between healthy and diseasedpanicle necks caused by Pyricularia oryzae were observed using electron-microscope. In the diseased panicle neck, the infection hyphae of the rice blast pathogen grew through the sclerenchymatous fiber tissue and reached to the central internal lacuna. Since the pathogen grew through the sclerenchymatous fiber tissues, the vascular bundle composed with xylem and phloem had been destroyed and finally the nutrients from the leaf and stem were not able to be transported into the grains. Infection of panicle base by the blast pathogen until 20 days after heading caused more than 50% of yield loss in both Jinmibyeo and Chucheongbyeo. There was a positive correlation between incidence of the panicle blast and rice yield losses. The regression equations between incidence of the panicle blast and yield losses were y= -3.61+496.7 ($R^2$=0.70) in Jinmibyeoand y=-3.93+520.2 ($R^2$=0.82) in Juanbyeo. The panicleblast caused deterioration of grain quality. Healthy grain rate was reduced by increase of panicle blast infection.

• Korean journal of applied entomology
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• v.19 no.1 s.42
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• pp.11-20
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• 1980

Percent penetration on a specific rice variety was more affected by blast fungus isolate or predisposition temperature than by temperature and isolate combinations. A susceptible variety tested remained continuously susceptible regardless of whether the variety was grown at different temperature regimes and exposed to isolates/races with differences in pathogenicity and virulence. The expression of virulence by a particular blast fungus isolate race was observed to be changed by subjecting rice host plants to different predisposing temperature conditions prior to inoculation.

• Korean Journal of Agricultural Science
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• v.16 no.1
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• pp.1-18
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• 1989

This experiment was undertaken to clarify derivation of resistance of Japonica type of rice varieties to rice blast in Korea and to classify Japonica type of rice varieties on the basis of their rice blast reaction in the blast nuisery test. 1. The resistance of Iljin, Kwancheok 9, Koshi, Baedal and Paldal, Jaekeon, Sinpung, Jinheung, Hokwang and Palkeum, and Gwangmyungbyeo and Yeongdeogbyeo to rice blast was derived from Kyudai Taicho Asahi 3, Futaba and 2067, respectively. 2. The resistance of Kwanok, Mankyeong and Nongbaek to the rice blast was derived from Kanto 55, Hokwang and Kusabue, and Ishigarisiroge, respectively. 3. The resistance of Seomjinbyeo, Sinseonchalbyeo, Donghaebyeo and Tamjinbyeo to the rice blast was derived from Milyang 20 and the source of resistance to the rice blast in Jinjubyeo and Daecheongbyeo was HR 769 or HR 1590. 4. The resistance of Dobongbyeo, Gwanagbyeo and Chiagbyeo to the rice blast was derived from Tjina, Kongo and Kuik 90, respectively. 5. The resistance of Seolagbyeo, Seonambyeo, Kihobyeo, Namyangbyeo, Samnambyeo, Seohaebyeo, Whaseongbyeo, Daegwanbyeo and Taeseongbyeo, and Sobaegbyeo, Odaebyeo and Unbongbyeo to the rice blast was derived from Fuji 280 and Fuji 269, respectively. 6. The source of resistance to the rice blast in Cheonmabyeo and Baegambyeo was BL 7 and Nongbaek, the resistance of Dongjinbyeo and Sangpungbyeo to the rice blast was derived from Satominori and Simokita, respectively. 7. Japonica type of rice varieties was classified into eleven varietal groups according to their reaction to the blast as follows. Eight varieties of Jinheung group, two varieties of Dongjinbyeo group, two varieties of Jinjubyeo group, three varieties of Gwanagbyeo group, four varieties of Sobaegbyeo group, one variety of Nongbaek group, two varieties of Baegambyeo group, five varieties of Sinseonchalbyeo group, five varieties of Seonambyeo group, two varieties of Taeseongbyeo group and some variety of Nagdongbyeo group.

• Korean Journal of Agricultural Science
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• v.16 no.2
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• pp.129-137
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• 1989

This experiment was undertaken to clarify derivation of resistance of Tongil type of rice varieties to rice blast in Korea and to classify Tongil type of rice varieties on the basis of their rice blast reactions in th blast nursery test. 1. The resistance of Tongil, Josaengtongil, Yeongnamjosaeng, Hwanggeumbyeo, Honamjosaeng, Noupung, Milyang 21, Milyang 22, Milyang 23, Raekyung, Manseogbyeo, Yongmunbyeo and Yongjubyeo to rice blast was derived from IR 8 or IR 24. 2. The resistance of Milyang 20, Nampungbyeo and Milyang 42, and Samseongbyeo, Seogwangbyeo, Pungsanbyeo and Shingwangbyeo to the rice blast was derived from IR 946 and IR 1539, and IR 1545, respectively. 3. The resistance of Palgwangbyeo, Sujeongbyeo, Hangangchalbyeo, Baegunchalbyeo, Samgangbyeo and Weonpungbyeo, and Taebaegbyeo and Chupungbyeo, and Kayabyeo to the rice blast was derived from IR 2061(IR 29), IR 747 and IR 32, respectively. 4. Cheongcheongbyeo, and Jungweonbyeo and Namyeongbyeo, and Changseongbyeo to the rice blast was derived from IR 2035, IR 5533, and HR 2797 and HR 1671, respectively. 5. Tongil type of rice varieties was classified into Tongil group, Milyang 30 group, Baegyangbyeo group and Taebaegbyeo group.

• Korean journal of applied entomology
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• v.19 no.4 s.45
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• pp.203-211
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• 1980

The pattern of blast disease incidence of Tonsil-line rice varieties derived from the cross between Indica and Japonica type was quite different from that of Japonica-type rice varieties. The former showed discontinuity between the incidence of leaf blast and panicle blast; the incidence .of leaf blast was slight, while that of panicle blast was very severe. Different level of nitrogen fertilizer applied influenced significantly the incidence of leaf blast but influenced slightly the incidence of panicle blast of Tongil-line rice varieties. The infection percentage of panicle blast of Tongil-line rice varieties was about $90\%$ and most of them were infected in leaf sheaths during booting stage, but infection of panicle blast of Japonica-type rice varieties in leaf sheaths during booting stage was very low, only about $3\%$. Infection route of panicle blast in leaf sheaths during booting stage, microflora in leaf sheaths, and specific susceptibility of young panicle to blast disease were investigated in the epidemiological point of view.

• Research in Plant Disease
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• v.10 no.1
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• pp.69-72
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• 2004

The control activity of isoprothiolane and tricyclazole mixed with carbosulfan, and probenazole by the nursery treatment was performed against rice leaf and neck blast caused by Magnaporthe grisea. In the paddy field, three fungicides showed good activities against leaf blast 3 months after nursery treatment. Especially the activity of tricyclazole against leaf blast gradually increased by the laps of time to 85.5％, which was assessed at 6 September,2003. Although the control value of isoprotholane and tricyclazole mixed with carbosulfan against neck blast was 47.5％ and 61.1％, respectively, probenazole showed a very high activity against not only leaf blast but also neck blast, of which that was 91.2％. No phytotoxicity was observed in all the treatments after transplanting rice seedling in the paddy field. Based on these results, three systemic fungicides tested in this study showed such a good potential that they might be used to formulate the nursery treating granule.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.277-282
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• 1983

Number and percentage of diseased area of leaf blast lesions formed on different leaf location were mostly distributed from the flag leaf(n-1) to the 3rd leaf from the top(n-3) in Tongil line rice varieties and on the 2nd leaf from the top(n-2) in Japonica type rice varieties. Especially leaf lesions of Nopung which was more susceptible to leaf blast among Ton1 line rice varieties were mostly distributed on flag leaf. Relation between the degree of lesion distribution and level of fertilizer was more clear with an increase of fertilizer quantity. Leaf blast lesions of rice varieties were generally distributed from the flag leaf to the with leaf from the top but mainly those at flag leaf and the 2nd leaf from the top were found to be most responsible for inoculum source of panicle blast after booting stage. Increase of the conidia formation was resulted from fluctuation of temperature$(24^{\circ}C\~16^{\circ}C)$ in low temperature range after booting stage and many inoculum sources were supplied on panicles until the end of September without impeding dispersal from leaf blast lesions as an inoculum source of panicle blast.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.64.2-64
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• 2003

Twenty-seven monogenic rice lines harboring major resistant gene for blast were screened to analyze their resistance spectrum to Korean blast fungus population using 190 isolates collected from 1985 to 2002. Especially, the monogenic line containing Pi-9 gene was screened using 320 isolates. Based on the monogenic lines-blast isolate interactions, the 27 rice lines were classified into 9 groups. The chinese rice cultivar LTH showed susceptible to all the tested isolates. Those lines IRBLz-Fu, ERBL5-M and IRBL9-W harboring Pi-z, Pi-5, and Pi-9, respectively showed broader spectrum of resistance than those rice lines having Pi-19, Pi-7 etc. Interestingly, the Pi-9 gene(IRBL9-W) showed resistance to most isolates collected before 2000, but it showed susceptible reactions to 5％ and 20％ of blast fungus population in 2001 and 2002, respectively. Population of virulent isolates to Pi-ta, Pi-b, and Pi-7 also were increased in 2002 compared to those before 2000.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.67.2-68
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• 2003

A rice cultivar, Taebaegbyeo, is highly resistant to rice blast and moderately resistant to bacterial leaf blight (BLB) caused by Magnaporthe grisea and Xanthomonas oryzae pv. oryzae, respectively. To study the rice disease resistance mechanism, we generated rice deletion M3 mutants by gamma-ray irradiation. Blast and BLB responses of 16,000 M3 mutants were screened by inoculating mixtures of 4 races (KJ-201, H-1113a, KI-313, KI-409) of M. grisea and 3 Korean races of X. oryzae pv. oryzae. We selected so far 21 M3 mutants of Taebaegbyeo showing high susceptibility to the diseases. One of the mutants, KCT-6417, was susceptible to KI-1113a race of M. grisea, suggesting the deletion of a race-specific blast resistance gene in the mutant. To isolate rice genes involved in blast resistance and defense response, we take a PCR-based suppression subtractive hybridization approach using cDNAs of blast-inoculated wild type and the KCT-6417 as a tester and a driver, respectively. Genes specifically expressed in the wild type will be presented. The selected genes would give us a clue to understand mechanism for the race specific resistance and defense responses against M. grisea H-1113a in Taebaegbyeo.

• Research in Plant Disease
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• v.25 no.3
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• pp.103-107
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• 2019

Roles of nutrients in controlling plant diseases have been documented for a long time. Among the nutrients having impact on susceptibility/resistance to crop diseases, nitrogen is one of the most important nutrients for plant growth and development. In rice plants, excess nitrogen via fertilization in agricultural systems is known to increase susceptibility to the rice blast disease. Mechanisms underlying such phenomenon, despite its implication in yield and sustainable agriculture, have not been fully elucidated yet. A few research efforts attempted to link nitrogen-induced susceptibility to concomitant changes in rice plant and rice blast fungus in response to excess nitrogen. However, recent studies focusing on phytobiome are offering new insights into effects of nitrogen on interaction between plants and pathogens. In this review, I will first briefly describe importance of nitrogen as a key nutrient for plants and what changes excess nitrogen can bring about in rice and the fungal pathogen. Next, I will highlight some of the recent phytobiome studies relevant to nitrogen utilization and immunity of plants. Finally, I propose the hypothesis that changes in phytobiome upon excessive nitrogen fertilization contribute to nitrogen-induced susceptibility, and discuss empirical evidences that are needed to support the hypothesis.