• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.3
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• pp.251-255
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• 2004

The epidemics of rice blast which occurred in south parts of Korea during the period from 1999 to 2001 and damaged several high quality rice cultivars developed using "Milyang 95" and/or "Milyang 96" as a parent. Genetic diversity of 23 rice cultivars including "Milyang 95" and it's relatives was assessed using 54 simple sequence repeats (SSR) markers reported to be linked to major blast resistance genes. Fifty-four SSR markers representing fifty-seven loci in the rice genome detected polymorphism among the 23 cultivars and revealed a total of 170 alleles with an average of 3.0 alleles per primer, The number of amplified bands ranged from 1 to 7. Several SSR markers including RM249, RM206 and OSR20 were informative for assessing the genetic diversity of relatively closed japonica rice cultivars. The 23 cultivars were classified into four groups by cluster analysis based on Nei's genetic distances, and the cultivars developed from same parents showed a tendency to cluster together that is consistant with genealogical information. High quality rice cultivars, Daesanbyeo, Donganbyeo, and Milyang 95 belonged to the same cluster, At the loci, RM254 and OSR32, all of the cultivars derived from the crosses using "Milyang 95" shared same alleles, suggesting that these japonica cultivars might carry alleles that are identical by descent. Evaluation of 23 rice cultivars against blast needs to be confirmed regarding the relationship between genotype and blast resistance.p between genotype and blast resistance.

• 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.

• Research in Plant Disease
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• v.22 no.3
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• pp.202-207
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• 2016

Rice bacterial blight and blast are devastating rice diseases in worldwide. Riboflavin, vitamin B2, is an essential nutrient for human health, and is known to be as a growth regulator and as a plant defense activator against pathogens in plants. In this study, we investigated possibility of increasing internal vitamin B contents and inducing resistances against rice diseases by external foliar application of a riboflavin-based formulator called BioDoctor. In planta bioassay indicated that pretreatment of the foliar application of 1,000-fold or 500-fold diluted BioDoctor significantly induced disease resistance against rice blast and bacterial blight. In addition, about four fold higher levels of riboflavin contents were detected in the BioDoctor treated rice grain and stem compared to those of untreated rice. Our results indicated that foliar application of the riboflavin has a great potential to control plant diseases and to enhance internal vitamin contents in rice.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.199-214
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• 1977

These studies were conducted to obtain basic information of the rice blast resistance in comparision with blast occurrence patterns in the blast nursery test in Korea. One hupdred and twenty nine rice varieties including several blast differential varieties and 30 combinations of pedigree lines were tested at six different locations, Suweon, Chulweon, Chuncheon, Iri, Jinan, Imsil, and Milyang, in 1976~1977. The results obtained are summarized as follows: 1. When blast resistance was tested using three sets of differential varieties at six locations, prevalent races were different depending on the location and differential variety set tested. 2. There were regional differences in blast disease reation among Japonica rice varieties and among Indica${\times}$Japonica crosses. 3. At Suweon blast disease reactions of pedigree lines were different from that at Imsil. 4. Three varietal groups were made depending on the develpment of rice blast in the nursery test. 5. In general, highly resistant varieties to rice leaf blast were also resistant to neck blast, but there were exceptions.

• 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.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.

• Korean Journal Plant Pathology
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• v.3 no.1
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• pp.3-7
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• 1987

Ethanol-soluble amino acids and phenolics in healthy and blast-infected leaves of the susceptible rice cultivar Nakdong and adult-plant-resistant cultivar Dobong were quantitatively analyzed, At the 3 days after inoculation, the levels of soluble amino acids and phenolics in the infected fifth and eighth leaves of the two cultivars ere similar to those of comparable healthy controls. As blast lesions appeared on the leaves at the 5 days after inoculation, the soluble amino acids and phenolics began to increase. At the 7 days after inoculation, the levels of amino acids and phenolics were about 1.5-3 times more than those in healthy controls at the five-and eight leaf stages. The adult-plant-resistant cultivar Dobong showed higher amounts of soluble amino acids and phenolics in both healthy and infected fifth and eighth leaves than did the susceptible cultivar Nakdong, although Dobong was less infected by Pyricularia oryzae than Nakdong, The pronounced increases in amino acids and phenolics in rice leaves of the cultivar Dobong during the blast infection may play an important role in the expression of adult-plant resistance to blast.

• Plant Breeding and Biotechnology
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• v.7 no.3
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• pp.272-286
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• 2019

Developing elite hybrid rice varieties is one important objective of rice breeding programs. Several genes related to male sterilities, restores, and pollinators have been identified through map-based gene cloning within natural variations of rice. These identified genes are good targets for introducing genetic traits in molecular breeding. This study was conducted to breed elite hybrid lines with major genes related to hybrid traits and disease/insect resistance in 240 genetic resources and F₁ hybrid combinations of rice. Molecular markers were reset for three major hybrid genes (S5, Rf3, Rf4) and thirteen disease/insect resistant genes (rice bacterial blight resistance genes Xa3, Xa4, xa5, Xa7, xa13, Xa21; blast resistance genes Pita, Pib, Pi5, Pii; brown planthopper resistant genes Bph18(t) and tungro virus resistance gene tsv1). Genotypes were then analyzed using molecular marker-assisted selection (MAS). Biological assay was then performed at the Red River Delta region in Vietnam using eleven F₁ hybrid combinations and two control vatieties. Results showed that nine F₁ hybrid combinations were highly resistant to rice bacterial blight and blast. Finally, eight F₁ hybrid rice varieties with resistance to disease/insect were selected from eleven F₁ hybrid combinations. Their characteristics such as agricultural traits and yields were then investigated. These F₁ hybrid rice varieties developed with major genes related to hybrid traits and disease/insect resistant genes could be useful for hybrid breeding programs to achieve high yield with biotic and abiotic resistance.

• Korean Journal of Breeding Science
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• v.40 no.4
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• pp.408-413
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• 2008

Rice blast resistance is considered one of the most important traits in rice breeding and the disease, caused by Magnaporthe grisea Barr, has brought significant crop losses annually. Moreover, breakdown of resistance normally occurs in two to five years after cultivar release, thus a more durable resistance is needed for better control of this disease. We developed a new variety, Keumo3, which showed strong resistance to leaf blast. It was tested in 2003 to 2007 at fourteen blast nursery sites covering entire rice-growing regions of South Korea. It showed resistance reactions in 12 regions and moderate in 2 regions without showing susceptible reactions. Durability test by sequential planting method indicated that this variety had better resistance. Results showed that Keumo3 was incompatible against 19 blast isolates with the exception of KI101 by artificial inoculation. To understand the genetic control of blast resistance in rice cultivar Keumo3 and facilitate its utilization, recombinant inbred lines (RIL) consisting of 290 F5 lines derived from Akidagomachi/Keumo3 were analyzed and genotyped with Pizt InDel marker zt56591. The recombination value between the marker allele of zt56591 and bioassay data of blast nursery test was 1.1%. These results indicated that MAS can be applied in selecting breeding populations for blast resistance using zt56591 as DNA marker.