• The Plant Pathology Journal
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• v.29 no.4
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• pp.435-439
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• 2013

Rice blast fungus, Magnaporthe oryzae, inflicts serious damage to global rice production. Due to high variability of this fungal pathogen, resistance of newly-released rice cultivars is easily broken down. To understand the population structure of M. oryzae, we analyzed the genetic diversity of the Korean population using multilocus microsatellite typing. Eleven microsatellite markers were applied to the population of 190 rice isolates which had been collected in Korea for two decades since the 1980's. Average values of gene diversity and allele frequency were 0.412 and 6.5, respectively. Comparative analysis of the digitized allele information revealed that the Korean population exhibited a similar level of allele diversity to the integrated diversity of the world populations, suggesting a particularly high diversity of the Korean population. Therefore, these microsatellite markers and the comprehensive collection of field isolates will be useful genetic resources to identify the genetic diversity of M. oryzae population.

• Korean Journal Plant Pathology
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• v.1 no.3
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• pp.178-183
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• 1985

The present researches were carried out to investigate the peroxidase activity in association with the reactions of the 4 cultivars of rice plant, Nagdong, Jinheung, Nongbaek and Taebaek to Pyricularia oryzae race KJ-I0l and KJ-301. Although the peroxidase activity was increased during the growth of the rice seedlings, the significant difference in the activity was not found among 4 cultivars. After inoculation of the fungus, the peroxidase activity was enhanced in diseased leaves, being considerably higher in the compatible than in the incompatible cultivars. The isozyme bands of peroxidases observed in mycelium of rice blast fungus were not found in the diseased leaves on the gel electrophoresis. The peroxidase activity was not affected by the increased application of nitrogenous fertilizer.

• The Plant Pathology Journal
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• v.28 no.4
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• pp.364-372
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• 2012

Xanthomonas oryzae pv. oryzae causing bacterial leaf blight disease in rice produces and secretes Hpa1 protein that belongs to harpin protein family. Previously it was reported that Hpa1 induced defense responses when it was produced in tobacco. In this study, we expressed hpa1 gene in rice and Arabidopsis to examine the effects of Hpa1 expression on disease resistance to both fungal and bacterial pathogens. Expression of hpa1 gene in rice enhanced disease resistance to both X. oryzae pv. oryzae and Magnaporthe grisea. Interestingly, individual transgenic rice plants could be divided into four groups, depending on responses to both pathogens. hpa1 expression in Arabidopsis also enhanced disease resistance to both Botrytis cineria and Xanthomonas campestris pv. campestris. To examine genes that are up-regulated in the transgenic rice plants after inoculation with X. oryzae pv. oryzae, known defense-related genes were assessed, and also microarray analysis with the Rice 5 K DNA chip was performed. Interestingly, expression of OsACS1 gene, which was found as the gene that showed the highest induction, was induced earlier and stronger than that in the wild type plant. These results indicate that hpa1 expression in the diverse plant species, including monocot and dicot, can enhance disease resistance to both fungal and bacterial plant pathogens.

• Journal of Life Science
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• v.10 no.1
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• pp.107-113
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• 2000

This study carried out to investigate activities of the superoxide dismutase(SOD), peroxidase(POD) and diterpene cyclase of rice plant treated by environmental stress conditions. The rice leaves of Ilpum was shown to have the most highest specific activity of POD. POD activity in the susceptible cv. Ilpum and Hwasung during the disease progress show a increase, while for a decreasing activity in the resistant cv. Dasan. SOD activity of rice plants treated by chitosan were increased as the treatment concentration increased. At the chitosan application, the SOD activity in the susceptible cv. Hwansung at the rice leaves 14days after treatment was higher in treatment than chitosan-untreated control. The activity of POD in the susceptible cv. Ilpum decreased as long as UV-B irradiation, while that in the resistant cv. Dasan increased. Futhermore, activity of that in Dasan were similar to as time on UV irradiation, Hwasung showed two times higher than untreated control at 40 minutes after UV-B exposure. The activity of diterpene cyclase in rice plants inoculated with Pyricularia oryzae has much higher tendency than UV-B irradiation. The activity of diterpene cyclase in the rice leaves gradually increased until 5 days after inoculation with Pyricularia oryzae.

• Korean Journal of Agricultural Science
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• v.51 no.2
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• pp.227-238
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• 2024

Methane (CH₄) is an important greenhouse gas, with a short-term greenhouse effect 80-fold that of carbon dioxide. Blast furnace slag used as a base ingredient for silicate fertilizer, and contained Fe³⁺, which acts as reduction of CH₄ emissions in flooded rice paddy. This study was evaluated the effects of the silicate fertilizer with different rates of the iron slag on CH₄ emissions and rice growth. In this study, the SF 0.0% was applied with silicate fertilizer containing 0.0% of the iron slag, while the SF 2.5% and SF 5.0% were treated with silicate fertilizer containing 2.5 and 5.0%, respectively. The CH₄ emissions during rice cropping period were assessed using a closed-chamber method and then determined by Gas chromatography. The CH₄ fluxes were reduced by 17% (SF 0.0%), 17% (SF 2.5%), and 8% (SF 5.0%) compared to the treatment with only-inorganic fertilization (control). Conversely, rice grain yield increased by 15 - 30% compared to the control owing to the improvement of soil quality by silicate fertilization. In particular, soil pH, available phosphorus and available silicic acid content were increased with the increase in the iron slag rates from 0.0 to 5.0%. These contributed to a significant increase in rice growth such as 1,000-grains weight and percentage of filled grains. Consequently, these findings were indicated that the application of silicate fertilizer containing 2.5 - 5.0% of iron slag would be the most effective in both CH₄ reduction and rice growth.

• Korean Journal of Breeding Science
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• v.42 no.3
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• pp.313-317
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• 2010

There are the farmer's needs to develop early-maturing cultivar adaptable to mid-northern inland plain and alpine area. Furthermore, it is required to develop a rice variety to produce new rice before concentrated marketing dates, even in the years of early Chuseok. 'Joun' is a new extremely early-maturing japonica rice cultivar developed in 2009 from the cross of SR14880-173-3-3-2-2-2/Unbong20 at Cheolwon Substation, National Institute of Crop Science (NICS), Rural Development Administration (RDA). The heading date of 'Joun' is July 23 in mid-northern alpine area, which is 7 days earlier than that of Odaebyeo. It has about 61 cm in culm length with semi-erect plant type. Panicle has a few awns and its exertion is good. The number of spikelets per panicle is smaller than that of Odaebyeo and 1,000 grain-weight of brown rice is 21.2 g which is less than 26.3 g of Odaebyeo, but the complete grain ratio is higher. Milled kernels are translucent with non-glutinous endosperm and palatability of cooked rice is good. It shows strong resistance to cold treatment, lodging, premature heading, wilting and viviparous germination during ripening stage. This cultivar shows resistance to leaf blast disease but susceptible to bacterial blight, virus disease and insect pests. The milled rice yield performance of 'Joun' is about 5.18 MT/ha by ordinary culture in local adaptability test for three years. This cultivar may be highly adaptable to the mid-northern inland plain and alpine area, north-eastern coastal area and middle plain area.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.61-71
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• 1968

1. In pot exreriments, the leaf blades of rice plants grown on Akiochi soil were weakened and the leaves dropped noticeably. This phenomenon could be prevented with application of silicate materials such as potassium silicate, Wallastonite and silicate slag (normally used silicate fertilizer in Korea). 2. Grain yield was increased by application of all the silicate materials. The effect of wollastonite was not lower than the effect of silicate slag. 3. Basal application of wollastonite gives a higher effect on the grain yield than top dressing. With higher wollastonite application, the nitrogen effect on the grain yield increases. This increase in nitrogen effect becomes more pronounced when the nitrogen level is higher. 4. Silica content in the plant waas increased by application of silicate materials to the soil. The increase in silica content in the plant was most noticeable with wollastonite. Basal application of wollastonite proved to be more effective than top dressing. Iron and nitrogen content in the plant decreased by application of the silicate materials. 5. The application of the silicate materials to Akiochi soil increases the resistance of rice to leaf blast, neck blast and Helminthosporium leaf spot. Among the silicate materials, wollastonite was most effective. 6. Damage by leaf blast increased proportionally with the nitrogen level, but decreased clearly with increase in wollastonite level. This phenomon was most pronounced for late transplanting time. 7. Damage by Helminthosporium leaf spot was also proportionally reduced by wollastonite application.

• Journal of Life Science
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• v.19 no.3
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• pp.343-348
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• 2009

Magnaporthe oryzae, a major cause of rice blast, is one of the most destructive plant fungal pathogens. Secretion of reactive oxygen species (ROS) during the infection phase of plant pathogenic fungus plays a key role in the defense mechanism of a plant. ROS causes oxidative damage and functional modification to the proteins in a pathogenic fungus. Methionine, especially, is a major target of ROS, which oxidizes it to methionine sulfoxide. To survive from the attack of ROS, plant pathogenic fungus has antioxidative systems - one example would be methionine sulfoxide reductase B (MSRB), which reverses the oxidative alteration of methionine to methionine sulfoxide. In the present study, identification and molecular characterization of the MSRB gene in M. oryzae KJ201 were investigated. The MSRB gene was amplified by PCR from the M. oryzae KJ201 genomic DNA. The copy number of MSRB in the genome of M. oryzae KJ201 was identified by Southern blot analysis, which revealed that the gene exists as a single copy. To study the molecular function of an MSRB gene, the expression level of the MSRB gene was assayed with hydrogen peroxide treatment by Northern blot analysis and RT-PCR. The expression of the MSRB gene was increased by treatment of hydrogen peroxide, without significant correlation to hydrogen peroxide concentrations. These results indicate that the MSRB gene in M. oryzae KJ201 could contribute to protection against plant defense compounds such as ROS and offer a novel strategy for the control of rice blast.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.249-261
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• 2006

Fifty compounds such as ester, sulfonyl ester, carbamate, ether and phosphoyl ester derivatives of 4-isopropyl-3-methylphenol(I) and 5-isopropyl-3-methylphenol(II) were synthesized. These derivatives were identified by IR, GC/MS and $^1H$-NMR spectra. Their in vitro antifungal activities were tested against 10 plant pathogenic fungi. Among them, several compounds showed potent in vitro antifungal activity. The selected compounds showing potent in vitro antifungal activity were tested for their in vivo antifungal activities against 5 plant diseases such as rice blast, rice sheath blast, cucumber anthracnose, cucumber gray mold and tomato late blight. As a result, 4-isopropyl-3-methylphenyl(2-amino-thiazole-4-yl)methoxyiminoacetate(I-7a) showed a potent in vivo antifungal activity against rice blast. Both methyl (4-isopropyl-3-methylphenoxy)acetate(I-4d) and methyl (5-isopropyl-3-methylphenoxy)acetate(II-4d) effectively inhibited the development of cucumber gray mold.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.183-192
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• 1982

The variability of rice productivity during last 2 decades (1961-1980) of ten years before and after the introduction of"Tongil" was reviewed from the epochal, regional and varietal points of view. During that period the cultivated area of paddy rice have remained almost unchanged, while the total rice production have got elevated from 3, 463 million metric tons in 1961 to 6.006 million metric tons in 1977, recording 73.4% increase. This remarkable increase in rice production is considered to be attributable much to the development and release of new high yielding variety, "Tongil", coupled with the amelioration of cultural techniques. However, in 1978 Tongil type varieties experienced the epidemic outbreak of blast disease due to the shifted race population of blast fungus and in 1980 recorded poor rice production as low as in 1960's due to the unfavorable weather stress throughout the rice growing season, giving rise to many problems awaiting solutions for securing the stabilized high production of rice. The rice yield has continued the gradual increase during last two decades but its difference between farmer and research organization have got wider from 79kg/10a during 1960 to 1971 to 101kg/l0a during 1972 to 1980, and also the inter-regional differences have been increased from 50-60kg/10a to 80kg/10a during those periods. Therefore, this proves that we have raised the upper boundary of rice yield by increasing the yield potential of rice variety but have not changed those absolute deviations. Estimates indicate that the increased rice production during that period was indebted 40 percent to the varietal improvement and 13 percent to the ameliorated agro-technologies, and the rest, 47 percent, could be ascribed to the other factors besides varieties and cultural technologies such as the improved agricultural environments, etc. Of course, even though it cannot be expected to unify the cultural environments and the cultural technologies, provided that much efforts are to be endeavored to minimize the yield difference of 20 percent between farmer and research organizations and the inter-regional yield difference of 20 percent, much increased rice production can be expected to be achieved with the current level of cultural technology and the yielding potential of the present rice varieties. In order to expedite the above effects on rice production the followings are to be put into practices consitently and steadfastly. 1. Reinforcement of breeding for varieties with high yielding potential and less susceptible to climatic-stress and pests, and of basic physicoecological studies of rice plant for improving the cultural technologies. 2. Continuous endeavor to secure the stabilized cultural environments by improving the soil fertility and increasing the drainage and irrigation facilities. 3. Political back-up to encourage the farmers' incentives for production 4. Precise surveys for agricultural statistics to facilitate the long-term planninge long-term planning.