• Research in Plant Disease
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• v.16 no.3
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• pp.224-231
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• 2010

Xanthomonas oryzae pv. oryzae, causal agent of bacterial leaf blight (BLB) of rice, had been collected and identified using Biolog and fatty acid analysis. Epidemics of BLB had been occurred all the times at several rice cultivating areas in Korea in 1999-2004. Most X. oryzae pv. oryzae isolated in 1999 and 2002 belonged to Korean race K1, but more than 50% of the pathogen isolated in 2003 belonged to Korean race K3. Especially, most pathogens isolated in Jeonnam and Joenbuk provinces belonged to Korean race K3. Inoculation test of near isogenic lines (NIL) of rice carrying single resistance genes against BLB showed that many isolates belonging to Korean race 1 reacted differently to diverse resistant monogenic lines of rice. Southern blot analysis also showed that the bacterial pathogens belonged to the same race had different numbers of avirulence genes. This results suggested that each Korean race type may respond to many resistance genes of rice. All the K3 races isolated in Jeonnam and Joenbuk provinces were able to cause disease on Xa3 monogenic lines of rice. Since most rice cultivars cultivated in Jeonnam and Jeonbuk were carrying Xa3 resistance genes, the bacterial pathogens isolated in Jeonnam and Jeonbuk were likely to develop to adapt to Xa3 resistance gene. Together with avirulence gene patterns of the bacterial isolates and the results of disease reaction of monogenic lines of rice to them, Korean X. oryzae pv. oryzae was classified into 19 pathotypes. This newly classified pathotypes should help the breeding of new resistance rice cultivars in Korea.

• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.97-101
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• 1985

Pathogenic variations of Xanthomonas campestris pv. oryzae were observed to Korean rice cultivars depending upon isolates in the same pathotype of the pathogen grouped by reactions of Japanese rice differentials. Using 201 Korean isolates of X. campestris pv oryzae 1,307 rice cultivars and promising lines were inoculated, and they were grouped into four varietal groups based on reactions. Of rice cultivars showing similar reactions to X. campestris pv. oryzae, five Korean rice cultivars Milyang 42, Hangangchalbyeo, Pungsanbyeo, Cheongcheongbyeo, and Milyang 23 were selected for classification of the pathogen into races The isolates only virulent to Milyang 23 were designated as race K1, the isolates virulent to Cheongcheongbyeo and Milyang 23 were designated as race K2, the isolates virulent to Pungsanbyeo, Cheongcheongbyeo and Milyang 23 were designated as race K3, the isolates virulent to Hangangchalbyeo, Pungsanbyeo, Cheongcheongbyeo and Milyang 23 were designated as race K4, and the isolates virulent to Milyang 42, Hangangchalbyeo, Pungsanbyeo, Cheongcheongbyeo and Milyang 23 were designated as race K5. Of 201 isolates tested, 114 isolates (56.7%) were classified as race K1, 47 isolates (23.4%) as race K2, 38 isolates (18.9%) as race K3, and 2 isolates (1.0%) as race K4. Reaction in each rice cultivar used as differentials in this test was also compared with that of rice differentials used for classification of X. campestris pv. oryzae into pathotypes in the previous work.

• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.292-298
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• 2009

A new rice cultivar "Keumo 3" was developed for adopting under double cropping system with after or before cash crop cultivation. It was selected from the cross-combination between YR17202 $F_2$/Shinkeumobyeo//YR15727-B-B-B-102. The parent, YR17202 $F_2$ individual plant, was used for tolerance to lodging, it derived from a cross between Nonganbyeo/Shinkeumobyeo. Nonganbyeo is well known to lodging tolerance cultivar, as well as biotic stress, because it was developed by crossing with Tongil type. And the YR15727-B-B-B-102 line used as another parent with short growth duration, likewise highly resistance to rice blast disease. The pedigree derived from the cross-combination YR17202 $F_2$/Shinkeumobyeo//YR15727-B-B-B-102 were generated to $F_7$, and a best line among them named as Milyang 201. After a series of yield trials, including local adaptability test conducted throughout the peninsular of Korea, Milyang 201 was registered with the name of "Keumo 3" in 2005. The cultivar belongs to a early maturing group and heads 4 days earlier than Keumobyeo, a standard cultivar. It has short culm, and less spikelet number per panicle than Keumobyeo. However, its milled rice yield grown under extremely late transplanting time, 10. July, over the 3 local sites for 2003-2005 years, averaged 4,48 MT/ha, which is 6% higher than the standard, Keumobyeo. "Keumo 3" has showed a durable resistance to leaf blast disease during fourteen blast nurseries screening covered from south to north in Korea for 2003-2007 years. And it was confirmed harbours pi-zt, a durable blast resistance gene. Moreover it was incompatible with 19 blast isolates under artificial inoculation, except one isolate, K1101. Additionally, "Keumo 3" exhibits resistance to $K_1$, $K_2$ and $K_3$ of bacterial blight pathogen, as well as strip virus disease resistance, and moderate resistance to dwarf virus disease. Consequently, the new rice cultivar "Keumo 3" would be well adopted where a bio stress makes a big problem annually.