• The Plant Pathology Journal
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• 제24권3호
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• pp.337-351
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• 2008

Host-pathogen interaction in rice bacterial blight pathosystem was analyzed for a better understanding of their relationship and recognition of stable pathogenicity among the populations of Xanthomonas oryzae pv. oryzae. A total number of 52 bacterial strains isolated from diseased leaf samples collected from 12 rice growing states and one Union Territory of India, were inoculated on 16 rice varieties, each possessing known genes for resistance. Analysis of variance revealed that the host genotypes(G) accounted for largest(78.4%) proportion of the total sum of squares(SS), followed by 16.5% due to the pathogen isolates(I) and 5.1% due to the $I{\times}G$ interactions. Application of the Additive Main effects and Multiplicative Interaction(AMMI) model revealed that the first two interaction principal component axes(IPCA) accounted for 66.8% and 21.5% of the interaction SS, respectively. The biplot generated using the isolate and genotypic scores of the first two IPCAs revealed groups of host genotypes and pathogen isolates falling into four sectors. A group of five isolates with high virulence, high absolute IPCA-1 scores, moderate IPCA-2 scores, low AMMI stability index '$D_i$' values and minimal deviations from additive main effects displayed in AMMI biplot as well as response plot, were identified as possessing stable pathogenicity across 16 host genotypes. The largest group of 27 isolates with low virulence, small IPCA-1 as well as IPCA-2 scores, low $D_i$ values and minimal deviations from additive main effect predictions, possessed stable pathogenicity for low virulence. The AMMI analysis and biplot display facilitated in a better understanding of the host-pathogen interaction, adaptability of pathogen isolates to specific host genotypes, identification of isolates showing stable pathogenicity and most discriminating host genotypes, which could be useful in location specific breeding programs aiming at deployment of resistant host genotypes in bacterial blight disease control strategies.

• Plant Resources
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• 제7권3호
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• pp.187-194
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• 2004

Sequence-tagged site (STS) markers tightly linked to the bacterial leaf blight (BLB) resistance genes, xa5, xa13 and Xa21, were used in this study. A survey was conducted to find polymorphisms between the resistant and susceptible germplasm in rice. 500 of Korean varieties and 100 of landraces were evaluated in this study. STS marker, RG207 was used to having xa5 resistance gene of rice germplasm. 27 varieties of Korean germplasm showed resistant for xa5 gene. The RG136 an xa-13 marker resulted in a single band of approximately 1kb in all the rice accessions studied. In order to detect polymorphism, digestion of the polymerase chain reaction (PCR) product was performed using a restriction enzyme Hinf Ⅰ. The resistant lines resulted in two bands 0.5kb on digestion with Hinf Ⅰ, while the same enzyme did not digest the PCR product of susceptible lines. No polymorphism was detected in Korean varieties and landraces, indicating that they probably do not contain xa13 gene. pTA248 an Xa-21 marker detected a band of 1kb in the resistant lines and bands of either 750bp or 700bp in the susceptible lines. Among germplasm tested, there are no varieties and landraces with Xa21 resistant gene. The results of the germplasm survey will be useful for the selection of parents in breeding programs aimed at transferring these bacterial blight resistance genes from one varietal background to another.

• 한국미생물·생명공학회지
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• 제46권4호
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• pp.346-359
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• 2018

Xanthomonas oryzae, a bacterial pathogen causing leaf blight disease (BLB) in rice, can cause widespread disease and has caused epidemics globally, resulting in severe crop losses of 50% in Asia. The pathogen is seed-borne and is transmitted through seeds. Thus, control of BLB requires the elimination of the pathogen from seeds. Concern about environment-friendly organic production has spurred improvements in a variety of biological disease control methods, including the use of bacteriophages, against bacterial plant pathogens. The present study explored the potential of bacteriophages isolated from diseased plant leaves and soil samples in killing the bacterial pathogen in rice seeds. Eight different phages were isolated and evaluated for their bacteriolytic activity against different pathogenic X. oryzae strains. Of these, a phage designated ${\varphi}XOF4$ killed all the pathogenic X. oryzae strains and showed the broadest host range. Transmission electron microscopy of ${\varphi}XOF4$ revealed it to be a tailed phage with an icosahedral head. The virus was assigned to the family Siphoviridae, order Caudovirales. Seedlings raised from the seeds treated with $1{\times}10^8pfu/ml$ of ${\varphi}XOF4$ phage displayed reduced incidence of BLB disease and complete bacterial growth inhibition. The findings indicate the potential of the ${\varphi}XOF4$ phage as a potential biological control agent against BLB disease in rice.

• Journal of Microbiology and Biotechnology
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• 제26권5호
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• pp.938-945
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• 2016

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious threats to rice production. In this study, screening of rice for resistance to BLB was carried out at two different times and locations; that is, in a greenhouse during winter and in an open field during summer. The pathogenicity of Xoo race K1 was tested on 32 Korean rice cultivars. Inoculation was conducted at the maximum tillering stage, and the lesion length was measured after 14 days of inoculation. Five cultivars, Hanareum, Namcheon, Samgdeok, Samgang, and Yangjo, were found to be resistant in both the greenhouse and open-field screenings. Expression of the plant defense-related genes JAmyb, OsNPR1, OsPR1a, OsWRKY45, and OsPR10b was observed in resistant and susceptible cultivars by qRT-PCR. Among the five genes tested, only OsPR10b showed coherent expression with the phenotypes. Screening of resistance to Xoo in rice was more accurate when conducted in open fields in the summer cultivation period than in greenhouses in winter. The expression of plant defense-related genes after bacterial inoculation could give another perspective in elucidating defense mechanisms by using both resistant and susceptible individuals.

• 한국육종학회지
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• 제40권4호
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• pp.443-446
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• 2008

'강백'은 국립식량과학원 벼맥류부에서 2006년도에 육성한 벼흰잎마름병 $K_{3a}$에 저항성인 국내 최초 품종으로 주요특성과 수량성을 요약하면 다음과 같다. 1. '강백'의 평균 출수기는 8월 11일로 '남평벼'보다 4일 빠른 중생종이다. 2. 주당수수, 수당립수, 등숙비율 및 정현비율은 '남평벼'와 비슷하며 현미천립중은 다소 가벼운 중립종이다. 3. 심복백은 거의 없고 '남평벼' 수준으로 맑고 투명하며 도정율, 아밀로스 및 단백질함량은 '남평벼'와 비슷하며 밥맛은 떨어지는 편이다. 4. 도열병은 중도저항성을 보였으며 흰잎마름병 $K_1{\sim}K_3$ 및 새로운 변이균 $K_{3a}$에 저항성인 국내 최초 자포니카 품종이나 줄무늬잎마름병, 오갈병 및 검은줄오갈병에는 약하고, 충에 대한 저항성은 없다. 5. '강백'의 쌀수량은 보통기 표준재배에서 5.28MT/ha으로 '남평벼'보다 7% 낮은 수량을 보였고 이모작재배에서 4.01 MT/ha, 만식재배에서는 4.34MT/ha의 수량을 보였다.

• Biodesign
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• 제7권2호
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• pp.35-37
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• 2019

Xanthomonas oryzae pv. oryzae (Xoo) is a plant pathogen, which causes a bacterial blight of rice. The bacterial blight is one of the most devastating diseases of rice in most of the rice growing countries and there is no effective pesticide against bacterial blight. The β-ketoacyl-acyl carrier protein synthase III (FabH) plays a key role in fatty acid synthesis (FAS) and is a promising drug target for the development of antibacterial agents. Xoo0878 gene, a fabH gene, from Xoo was cloned and its gene product Xoo0878 was expressed, purified and crystallized. Xoo0878 crystal diffracted to 2.1Å resolution and belonged to the triclinic space group P1, with unit-cell parameters a = 57.3Å, b = 64.7Å, c = 104.2Å and α = 81.6°, β = 84.7°, γ = 74.4°. There are four monomers in the asymmetric unit, with a corresponding crystal volume per protein weight of 2.65 ų Da^-1 and a solvent content of 53.6%. Xoo0878 structure will be useful to develop new antibacterial agents against Xoo.

• The Plant Pathology Journal
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• 제40권2호
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• pp.225-232
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• 2024

The microbiomes of two important rice cultivars in Vietnam which differ by their susceptibility to the bacterial leaf blight (BLB) disease were analyzed through 16S rRNA amplicon technology. A higher number of operational taxonomic units and alpha-diversity indices were shown in the BLB-resistant LA cultivar than in the BLB-susceptible TB cultivar. The BLB pathogen Xanthomonas was scantly found (0.003%) in the LA cultivar, whereas was in a significantly higher ratio in the TB cultivar (1.82%), reflecting the susceptibility to BLB of these cultivars. Of special interest was the genus Acholeplasma presented in the BLB-resistant LA cultivar at a high relative abundance (22.32%), however, was minor in the BLB-sensitive TB cultivar (0.09%), raising a question about its roles in controlling the Xanthomonas low in the LA cultivar. It is proposed that Acholeplasma once entered the host plant would hamper other phytopathogens, i.e. Xanthomonas, by yet unknown mechanisms, of which the triggering of the host plants to produce secondary metabolites against pathogens could be a testable hypothesis.

• The Plant Pathology Journal
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• 제28권4호
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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.

• 한국육종학회지
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• 제43권1호
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• pp.81-91
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• 2011

야생벼은 재배벼의 친환경적성을 강화시킬 수 있는 병해충 저항성 및 불량환경에 견딜 수 있는 유용한 유전자들의 보고로 알려져 왔다. 국내에서 육성된 벼 품종인 '화성'(AA게놈)와 야생벼인 Oryza. minuta(BBCC 게놈; Acc.=101141)간의 교잡을 통하여 종간잡종 후대들이 육성되었다. 불화합성과 초기분리세대의 극심한 불임을 극복하기 위해 배주배양으로 $F_1$ 개체를 확보하였으며, '화성'으로의 여교잡을 수 차례 실시하였다. 확립된 계통들에 대한 표현형 평가를 통하여 흰잎마름 병에 저항성을 발현하는 계통을 확인하고 '수원497호'라 명명하였다. '수원497호'와 '밀양23호'간의 교잡에서 작성된 $F_2$ 개체들을 유전자지도 작성 및 표현형조사에 활용하였다. 유전자지도 작성에 사용된 SSR 마커의 유전자형과 흰잎마름병균 접종에 따른 병반장길이간의 연관성분석을 수행하였다. '수원 497호'의 흰잎마름병저항성을 지배하는 주동유전자가 염색체 11번 말단에 표지 되었는데, 기존에 보고되어 온 흰잎마름병 저항성유전자들인 Xa3, Xa4, Xa26 및 Xa31 등이 표지 된 곳과 동일하였다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2020년도 춘계학술대회
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• pp.49-49
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• 2020

Bacterial leaf blight (BLB), caused by X. oryzae pv. oryzae(Xoo), is one of the most destructive diseases of rice due to its high epidemic potential. Understanding BLB resistance at a genetic level is important to further improve the rice breeding that provides one of the best approaches to control BLB disease. In the present investigation, a total of 10,000 accessions of rice germplasm were tested to resistance degree of four Korean isolated races (K1, K2, K3 and K3a) of Xoo by bioassay and a diverse 268 accessions was selected to the genome-wide association study (GWAS) using high quality 34,724 SNPs to identify the associated with resistance loci. LOC_Os04g53160 of chromosome 4 was significantly associated with K1 race resistant. LOC_Os11g46230 and LOC_Os11g47150 of chromosome 11 were highly associated with K2 and K3 races as 23.7 and 27.4 of -log(P) value, but K3a resistant loci was weakly associated at LOC_Os03g55270 of chromosome 3. The results of the GWAS validate known gene of BLB resistant and identified novel loci of R genes that provide useful targets for further investigation to help the breeding system and identified gene and QTL provide valuable sources for further functional characterization.