• The Plant Pathology Journal
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• v.36 no.3
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• pp.231-243
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• 2020

Rice blast, caused by Magnaporthe oryzae, is one of the most destructive rice diseases worldwide. The aim of this study was to screen bacterial isolates to efficiently prevent the occurrence of rice blast. A total of 232 bacterial isolates were extracted from nonrhizospheric rice soil and were screened for antifungal activity against M. oryzae using a leaf segment assay. Strains S170 and S9 showed significant antagonistic activity against M. oryzae in vitro and in leaf disk assays, and controlled M. oryzae infection under greenhouse conditions. The results showed that strains S170 and S9 could effectively control rice leaf blast and panicle neck blast after five spray treatments in field. This suggested that the bacterial strains S170 and S9 were valuable and promising for the biocontrol of rice disease caused by M. oryzae. Based on 16S rDNA, and gyrA and gyrB gene sequence analyses, S170 and S9 were identified as Bacillus amyloliquefaciens and B. pumilus, respectively. The research also demonstrated that B. amyloliquefaciens S170 and B. pumilus S9 could colonize rice plants to prevent pathogenic infection and evidently suppressed plant disease caused by 11 other plant pathogenic fungi. This is the first study to demonstrate that B. amyloliquefaciens and B. pumilus isolated from nonrhizospheric rice soil are capable of recolonizing internal rice stem tissues.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.383-395
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• 2014

When we investigated seed infestation by fungal pathogens from 51 varieties in 9 crops, the contamination rate of rice and sesame seeds was high. Therefore, to control seed-borne diseases, we obtained extracts from commercial products of Kimchi, Gochujang, Doenjang, Ganjang, Makgeolli and Tohajut and their suppressive effects against seed-borne diseases were studied. In addition, bacterial strains were screened to control rice seed-borne diseases in vitro and in vivo. Among forty food extracts, eleven food-extracts suppressed incidence of seedling rots in vitro and five food extracts increased 8-33% of healthy seedling in the greenhouse. Among 218 isolates from 40 fermented foods, 43 isolates showed high antifungal activity against seven fungal pathogens. When we tested 43 isolates for the reduction of rice seed borne disease, 32 isolates were able to reduce the rice seed borne disease. Among 32 isolates, 17 isolates reduced significantly seedling rot and increased healthy seedlings, the other isolates except for Kc4-2 and Mkl 2-2 increased shoot emergence and the percentage of healthy plants. Thirty isolates with high antifungal activity and suppressive effect against rice seedling rots were identified by 16S rRNA sequencing. Twenty one of thirty isolates were identified as Bacillus spp. Three isolates from Makgeolli were identified as Saccharomyces cerevisiae. B. amyloliquifaciens were isolated from six Korean traditional fermented foods except for Ganjang. B. amyloliquifaciens were majority in the effective bacterial population of Gochujang and Jutgal. Relatively diverse Bacillus species including B. subtilis, B. pumilus, and B. amyloliquificiens were isolated from Kimchi. The selected effective microorganisms from Korean fermented foods founded to be effective for controlling seed-borne diseases of rice in vitro and in the greenhouse. We think that Korean fermented foods and their useful microorganisms can be used as biocontrol agents for suppressing rice seed-borne diseases based on above described results.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.361-370
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• 1982

The effects of climatic factors on organisms lire variable and complex, and it, however, can be interpreted in terms of those on the distribution and those on the population densities. The distribution of an organism may largely be determined by the temperatures, except some temporal organisms which are depended on the air mass movements. Population density of an organism is determined by various climatic factors, such as previous winter temperature, temperature of growing season and rainfall. The start of growing season of the rice plants has been shifted to earlier since last decade in Korea. This may mean that the overall climatic condition during the growing season might be considerably different from those in past years, and such a difference in climatic conditions might have close relation with the recent status of the diseases and insect pests through direct effects on the physiology and population dynamics of the organisms, as well as through on the biotic associations of the pest organisms. The white back planthopper and brown planthopper have become the key insect pests in Korea in recent years. They are migratory and have high reproductive pontentials and more generations than average residential insects. The synchronization of the migrants and physiological condition of the rice plants seems to be the important factors in relation to the recent outbreaks of these insects; the high reproductive rate can be obtained with the growth stage of rice being 30-50 days after transplanting. The modication of the microclimate associated with high plant density and some other introduced new cultural techniques also have some relation with the outbreak. The key diseases of the rice are the blast disease, sheath blight and the bacterial leaf blight. For the rice blast, the seedling blast and leaf blast during the early growing season and the neck blast, have become more serious, the former may be related to hotbed nursery and the later may be related to the high humidity in early August, and synchronization of the heading time which has been shifted to early part from middle or late part of August. In general, for the rice diseases, the development of the new races have been the most serious which are largely resulted from the introduction of the new varieties, but it also seems to be related with the prolonged periods of the favorable condition associated with the shifted growing seasons. In general, the diseases and insect pest problems have become much more variable and complex, and control measures should be based on the thorough knowledge of the ecology of the pest organisms, that is, effects of various environmental factors on the disease cycle; spore release, spore deposition, infection, colonization and sporulation of the disease organisms, and those on the development, reproductive potentials, dispersal, age specific responses of the insects. The well organized real-time pest management systems, such as alfalfa weevil management system developed at the Purdue University in U.S., is the prime importance for the implementation of the pest management principles.

• Research in Plant Disease
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• v.12 no.3
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• pp.153-157
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• 2006

In 2005, average temperature was lower, and average rainfall was less than those of previous year. The diseases of rice, barley, pepper, chinese melon, apple and oriental pear were surveyed. Bacterial blight, bacterial grain rot, and panicle disease of rice, black rot of pear, and white rot and bitter rot of apple were severe. Especially, brown rot of rice occurred four times higher than those of previous year. Panicle blight of rice increased about 3 times, compared with the previous year, presumed that the higher rainy days, rainfall and RH promoted spread of the fungal pathogens to panicles of rice. The diseases of rice leaf blast, sudden wilt syndrome, downy mildew and powdery mildew of chinese melon in plastic greenhouse, and virus diseases of hot pepper occurred distinctly less than those of the previous year. Another diseases surveyed occurred similar or less.

• Culinary science and hospitality research
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• v.23 no.1
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• pp.19-27
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• 2017

The present study was aimed at evaluating whether white rice consumption has any association with selected measures of dietary intake and nutrients, including various variables of energy intake, major vitamin, mineral intakes, and the risk of health characteristics for over 60 years older. A total of 1,433 subjects (658 male and 775 females) 60 years or older from the fifth Korea National Health and Nutritional Examination Survey(KNHANES) 2010 participated and the Food Commodity Intake Database were used in this study. Levels of percent energy intake from rice were classified into 4 groups (R1, R2, R3, R4 groups: 25% of each) between male and female elderly using data from KNHANES. One of the interesting findings was that the higher rice consumers had a significantly sufficient intakes of a range of nutrients such as total energy intake, protein, carbohydrate, calcium, mineral, sodium, potassium, and niacin in female elderly, but not much in male. Other finding was that as the higher intake of rice group, prevalence of hypertension (53.5%, 63.4%, 50.3%, 46.3%, p=0.035), dyslipidemia (16.6%, 18.0%, 14.5%, 11.1%, p=0.008), sarcopenia (46.1%, 46.1%, 40.2%, 28.8%, p=0.012), sarcopenic obesity (25.4%, 31.5%, 23.7%, 15.5%, p=0.008) were significantly less than other groups in female, but not much in male. In conclusion, we obtained valuable basic information on recommended rice-centered diet could give us good nutritional status and eventually bring the prevention of some chronic diseases in elderly, especially in female.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.136-140
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• 2023

Rice panicle blast is one of the most serious diseases threatening stable rice production by causing severe damage to rice yields and quality. The disease is easy to occur under low air temperature and frequent heavy rainfall during the heading season of rice. In 2021, a rice panicle blast severely occurred in the Jeonbuk province of Korea. The incidence area of panicle blast accounted for 27.7% of the rice cultivation area of Jeonbuk province in 2021, which was 13.7-times higher than in 2019 and 2.6-times higher than in 2020. This study evaluated the incidence areas of rice panicle blast in each region of Jeonbuk province in 2021. The weather conditions during the heading season of rice, mainly cultivated rice cultivars, and the race diversity of the Jeonbuk isolates were also investigated. It will provide important information for the effective control of the rice panicle blast.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.245-257
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• 2023

The representative crop in the Republic of Korea, rice, is cultivated over extensive areas every year, which resulting in reduced resistance to pests and diseases. One of the major rice diseases, rice blast disease, can lead to a significant decrease in yields when it occurs on a large scale, necessitating early detection and effective control of rice blast disease. Drone-based crop monitoring techniques are valuable for detecting abnormal growth, but frequent image capture for potential rice blast disease occurrences can consume significant labor and resources. The purpose of this study is to early detect rice blast disease using remote sensing data, such as drone and satellite images, along with weather data. Satellite images was helpful in identifying rice cultivation fields. Effective detection of paddy fields was achieved by utilizing vegetation and water indices. Subsequently, air temperature, relative humidity, and number of rainy days were used to calculate the risk of rice blast disease occurrence. An increase in the risk of disease occurrence implies a higher likelihood of disease development, and drone measurements perform at this time. Spectral reflectance changes in the red and near-infrared wavelength regions were observed at the locations where rice blast disease occurred. Clusters with low vegetation index values were observed at locations where rice blast disease occurred, and the time series data for drone images allowed for tracking the spread of the disease from these points. Finally, drone images captured before harvesting was used to generate spatial information on the incidence of rice blast disease in each field.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2000.04a
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• pp.4-4
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• 2000

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.230.2-230
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• 2005

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.61-61
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• 2015

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most destructive diseases of rice worldwide. The rice - M. oryzae pathosystem has become a model in the study of plant - fungal interactions due to its economic importance and accumulating knowledge. During the evolutionary arms race with M. oryzae, rice plants evolved a repertoire of Resistance (R) genes to protect themselves from diseases in a gene-for-gene fashion. M. oryzae secretes a battery of small effector proteins to manipulate host functions for its successful infection, and some of them are recognized by host R proteins as avirulence effectors (AVR), which turns on strong immunity. Therefore, the analysis of interactions between AVRs and their cognate R proteins provide crucial insights into the molecular basis of plant - fungal interactions. Rice blast resistance genes Pik, Pia, Pii comprise pairs of protein-coding ORFs, Pik-1 and Pik-2, RGA4 and RGA5, Pii-1 and Pii-2, respectively. In all three cases, the paired genes are tightly linked and oriented to the opposite directions. In the AVR-Pik/Pik interaction, it has been unraveled that AVR-Pik binds to the N-terminal coiled-coil domain of Pik-1. RGA4 and RGA5 are necessary and sufficient to mediate Pia resistance and recognize the M. oryzae effectors AVR-Pia and AVR1-CO39. A domain at the C-terminus of RGA5 characterized by a heavy metal associated domain was identified as the AVR-binding domain of RGA5. Similarly, physical interactions among Pii-1, Pii-2 and AVR-Pii are being analyzed.