• Plant Disease and Agriculture
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• v.1 no.2
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• pp.9-17
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• 1995

• Research in Plant Disease
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• v.14 no.3
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• pp.165-170
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• 2008

One hundred and three isolates of Xanthomonas oryzae pv. oryzae in Korea were evaluated for their virulence on four near-isogenic lines (NILs) containing a single resistance gene, and Korean differential varieties. The resistant gene backgrounds of Cheongcheongbyeo, Pungsanbyeo, Hangangchalbyeo, Milyang42 were not completely understood and they were not suited for the classification of X. oryzae pv. oryzae. Four NILs, IRBB101, IRBB103, IRBB105, and IRBB107 were difference for characterizing races of X. oryzae pv. oryzae because they have a single resistance gene. These NILs may be useful differential set in examining pathogenic races of X. oryzae pv. oryzae in Korea. Based on the virulence of 103 isolates to new differential varieties, they were classified into 3 races.

• 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 of Food Science and Technology
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• v.20 no.3
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• pp.331-337
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• 1988

The thermal properties of typical five Indica and five Japonica rice varieties were investigated by Differential Scanning Calorimetry (DSC). There was no significant difference in gelatinization temperature between Indica and Japonica varieties, but the average enthalpy of gelatinization was larger in Indica types than that in Japonica. However, the enthalpy of melting of amylose-lipid complex was larger in Japonica types than that in Indica types. The DSC thermogram of hydrolyzed rice residue included a smaller peak of gelatinization with narrow range of temperature. Retrogradation of gelatinized rice kernel was also determined with DSC theremograms. The endothermic peak areas clearly increased with increasing storage time at $4^{\circ}C$ so that the area could be used as a measure of the relative degree of retrogradation. The results indicated that Samgang variety(Indica) retrograded more rapidly than Chuncheong variety(Japonica).

• Korean journal of applied entomology
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• v.17 no.1 s.34
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• pp.37-40
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• 1978

The resistance to bacterial leaf blight of Conventional varieties (chodongi, Yongcheon etc.) cultivated from 1920 to 1956 in Korea were tested by means of 5 pathotypes of causal organism Xanthomonas oryzase (Uyeda et lshiyama) DOWSON. The results of this test are: 1. Among 74 varieties, 69 varieties including 'Chodongji, Yongcheon, Aedhal, Yongsang, Daegu, Mitdhari, pungok, etc' belong to the Kinmaze group that is highly susceptible to this disease. 2. 3 varieties: Heukbal, Doipnam, Whangphan belong to the Kogyoku group. 3. 2 varieties: Namgok, Gangbukdo, show unknown reaciton to differential varieties. 4. In 69 varieties belonging to the Kinmaze group $99.5\%$ of the plants were infected by bacterial group I. $99.6\%$ in bacterial group II. $100\%$ in group III, $99.7\%$ in group IV, and $99.8\%$ in group V. 5. In 3 varieties belong to Kyogyoku group, $1.7\%$ of the plants were infected in bacterial group I. $98.8\%$ in group II, $100\%$ in group III, IV and $1.4\%$ in group V.

• Korean Journal Plant Pathology
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• v.11 no.3
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• pp.238-244
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• 1995

Severity of panicle blast disease on the leading cultivars of rice was investigated at nine locations of Korea during summer in 1993 with frequent raining and low temperature conditions. Incidence of panicle blast was 26% on Jinmibyeo, 23% on Chuncheongbyeo and 40% on Odaebyeo. Race distribution of Pyricularia grisea was examined from 1993 to 1994. A total of 1,098 isolates of the fungus obtained from the blast nurseries and framers; fields were screened using Korean differential varieties. Twenty one races were identified in 1993 and 19 races in 1994. KI-181, KJ-103, KJ-104, KI-241 and KI-209 were identified as new races, and KJ-301 (15%), KJ-201 (13%), KJ-105 (12%) and KI-409 (12%) were major races during 1993 and 1994. Race KI-197, which has a wide spectrum of virulence on rice cultivars, was isolated in a ratio of 8.3% and evenly distributed in the whole country. Some of the major and newly identified races during 1993∼1994 were used for spray-inoculation on leading cultivars and differential varieties in a greenhouse. We found that most of the cultivars were resistant to the major races, KJ-301 and KI-409, but were very susceptible to the new races, KI-241, KI-209, KI-181 and KJ-103.

• Korean journal of applied entomology
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• v.22 no.2 s.55
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• pp.52-66
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• 1983

The brown planthopper, N. lugens (Stal), has become a serious pest of rice in tropical Asia during the last decade. At high pest density, its feeding damage causes 'hopperburn' or complete wilting and drying of the rice plant. It also transmits grassy and ragged stunt virus diseases. The estimated losses caused by the pest in tropical Asia exceed $US\$300$ millions. While cultivation of resistant rice varieties has proved to be highly effective against the pest, their long-term stability is threatened because of the evolution of prolific biotypes which can destroy these varieties. At present, identification of biotypes is based principally on the differential reactions of host rice varieties to the pest and on host-mediated behavioral and physiological responses of the pest. Recent findings of morphological differences in adult rostrum, legs, and antennae, body parts that possess receptors for host plant location and discrimination, and cytological differences in N. lugens populations maintained as stock cultures strongly complement other biotype studies. So far, three N. lugens biotypes have been identified in the Philippines. Biotype I can survive on and damage varieties that do not carry and genes for resistance, while Biotype 2 survives on resistant varieties carrying Bph 1 gene and Biotype 3 on varieties carrying gene bph 2. However, none of these biotypes can survive on varieties with genes Bph 3 or bph 4. Several varieties which are resistant in the Philippines are susceptible in India and Sri Lanka as the South Asian biotypes of N. lugens are more virulent than Southeast Asian biotypes. To monitor the pest biotypes in different geographical regions and to identify new sources of resistance, an International Brown Planthopper Nursery has been established in many cooperating countries. The evolution of biotypes is an exceedingly complex process which is governed by the interactions of genetic and biological factors of the pest populations and the genetic makeup of the cultivated varieties. While the strategy for sequential release of varieties with major resistance genes has been fairly successful so far, the monegenic resistance of these varieties makes them vulnerable to the development of the pest biotypes. Therefore, present breeding endeavors envisage utilizing both major and minor resistance genes for effective control of the pest.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.556-561
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• 1989

Thermal properties of amylose-lysolecithin (AL) complex, amylose content and effect of lysolecithin on the gelatinization of rice starch were investigated by Differential Scanning Calorimetry (DSC). The melting temperature of AL complex was near to $108.5^{\circ}C$ and the melting enthalpy was about 1.0cal/g. The gelatinization temperature of rice starch was not affected by adding lysolecithin. However, the enthalpy of gelatinization was decreased. The amylose contents in rice varieties were calculated from melting enthalpy of AL complex. The amylose contents for Indica and Japonica types of rice were in the range of 16-19%, which were in good agreement with those determined by iodine binding method. Significant differences were not observed in the amylose contents between Indica and Japonica varieties.

• Korean journal of applied entomology
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• v.11 no.1
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• pp.41-43
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• 1972

1. In order to investigate the epidemic outbreak of rice blast disease on the resistant variety Kwankon in 1969, this investigation was undertaken as a basis for breeding resistant varieties. 2. The 16 isolates collected from Kyunggi area were inoculated at the 3-4 leaf stage on 12 Japanese differential varieties used for identifying races under greenhouse conditions. Out of 16 isolates 15 were identified as C race group and one as N race group. Of the 15 rates, nine were C-8, two were C-7 and two were C-1. Of the remaining two isolates, one was similar to C-1, and the other was similar to C-5. 3. It is concluded that the epidemic in the resistant variety 'Kwanok' was due to the occurrence of the C race group, which can infect the Chinese type varieties.

• Research in Plant Disease
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• v.10 no.4
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• pp.217-226
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• 2004

One hundred isolates of Magnaporthe grisea from Korea and China were characterized for pathogenicity using eight Korean differential varieties(KDV), six Chinese differential varieties(CDV) and six near isogenic lines(NILs) developed in China. The restriction length polymorphism of M. grisea isolates from each country also was analyzed using MGR586 as a probe. One hundred Korean isolates classified into 17 races on KDV were grouped into 29 pathotypes on Chinese near isogenic lines(NILs). Virulence of 46% of Korean isolates against all the six Chinese NILs indicated that the current six Chinese NILs alone was not enough to be used as differential varieties in Korea. Especially, susceptibility of the BL1 carrying resistance gene Pi-b to 70% of tested Korean isolates suggested that BL1(Pi-b) may not be a useful resistance source to Korean blast. Based on the virulence assays of M. grisea populations from each country were divided into two groups. About 50% of Chinese isolates showed similarity to the 30% of the Korean isolates. Especially, the isolates from northern part of China, where Japonica rice cultivars were grown, showed high similarity to the Korean isolates, while isolates from southern part of China, where Indica rice were mainly grown, showed low similarity to Korean isolates. The genome RFLPs of Korean isolates were quite different from those of southern part of China using MGR586 as a probe. These data indicated that the physiological and genetical characteristics of M. grisea population might be determined by strong interaction with cultivated rice.