• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.740-747
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• 2014

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

• 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.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.732-739
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• 2014

We describe the development of a polymerase chain reaction method for the rapid, precise, and specific detection of the Xanthomonas oryzae pv. oryzae (Xoo) K3a race, the bacterial blight pathogen of rice. The specific primer set was designed to amplify a genomic locus derived from an amplified fragment length polymorphism specific for the K3a race. The 1,024 bp amplicon was generated from the DNA of 13 isolates of Xoo K3a races out of 119 isolates of other races, pathovars, and Xanthomonas species. The assay does not require isolated bacterial cells or DNA extraction. Moreover, the pathogen was quickly detected in rice leaf 2 days after inoculation with bacteria and at a distance of 8 cm from the rice leaf 5 days later. The results suggest that this PCR-based assay will be a useful and powerful tool for the detection and identification of the Xoo K3a race in rice plants as well as for early diagnosis of infection in paddy fields.

• 한국응용곤충학회지
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• 제11권2호
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• pp.55-60
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• 1972

1. 지엽에 있어서 배수선의 또는 감수성인 품종이 저항성인 품종보다 평균 6개 이상 많았으며 중간성과 저항성 품종간에는 차이가 없었다. 2. 엽맥의 도관절의 길이는 감수성인 진흥, 김마제 수원 213호 등이 저항성 품종보다 길었으며 팔달 시로 가네 농릴 6호 등은 차이가 없었다. 3. 도관의 직경은 김마제쓱 수원 213호가 다른 4 품종에 비하여 길었으나 저항성품종과 감수성 품종간에는 유의차가 없었다. 4. 6-7엽기에 이른 뿌리의 후생도관은 진흥 김마제가 시로가에, 농릴 6호 보다 휠씬 많았으나 수원 213호는 예외적으로 후생도관수가 가장 적었다. 5. 저항성인 시로가네의 즙액에서는 감수성품종에 비하여 세균의 증식이 현저하게 억제 되였고 다른 품종들 간에는 차이가 없었다. 6. 열처리된 즙액에서는 저항성 품종이나 감수성품종에 관계없이 세균증식이 비슷하였고 전체적으로 신선한 즙액에서 보다 세균수가 훨씬 적었다.

• 한국육종학회지
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• 제49권3호
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• pp.235-244
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• 2017

'만백'은 농촌진흥청 국립식량과학원에서 벼흰잎마름병에 대한 저항성이 증진된 고품질 중만생 벼 품종을 개발하고자 육성되었다. 최고품질 중만생 벼 '호품'을 반복친으로하고 벼흰잎마름병 저항성 유전자가 집적된 육성계통 'SR30075'를 수여친으로 하여 작성된 여교배 $BC_1F_1$ 식물체를 약배양하여 계통육성과정, 생산력 검정시험 및 지역적응성 검정시험을 거쳐 육성되었다. '만백'은 벼흰잎마름병 저항성 유전자 Xa3와 xa5 두 개가 집적되어 있어 병원성이 강한 벼흰잎마름병 K3a 균계에 저항성이면서 국내 수집 16개 균주에도 모두 강한 광범위 저항성을 나타냈다. '만백'의 출수기는 평균 8월 19일로 '남평'보다 5일 늦은 중만생종이다. '만백'은 엽색이 진한 녹색을 띄며 간장이 '남평'보다 작은 단간 내도복 품종이다. 또한 수발아 내성을 가지고 있어 수발아에 대한 안정성 확보를 위한 육종소재로 활용될 수 있을 것으로 생각된다. 벼흰잎마름병 및 줄무늬잎마름병에는 저항성이나 도열병, 기타 바이러스병 및 해충에 대한 저항성은 없다. 쌀의 수량성은 '남평'과 비슷한 수준을 나타냈다. 쌀의 외관품위가 좋고 밥맛이 양호하여 벼흰잎마름병 저항성 품종의 품질 향상에 기여하였다. '만백'은 벼흰잎마름병에 대한 저항성이 증진된 고품질 벼 품종으로 벼흰잎마름병 발병상습지 재배에 접합하며 벼흰잎마름병 저항성 향상을 위한 육종사업에 활용되고 있다.

• The Plant Pathology Journal
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• 제37권4호
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• pp.396-403
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• 2021

Fire blight disease, caused by Erwinia amylovora, could damage rosaceous plants such as apples, pears, and raspberries. In this study, we designed to understand how E. amylovora affected other bacterial communities on apple rhizosphere; twig and fruit endosphere; and leaf, and fruit episphere. Limited studies on the understanding of the microbial community of apples and changes the community structure by occurrence of the fire blight disease were conducted. As result of these experiments, the infected trees had low species richness and operational taxonomic unit diversity when compared to healthy trees. Rhizospheric bacterial communities were stable regardless of infection. But the communities in endosphere and episphere were significanlty affected by E. amylovora infection. We also found that several metabolic pathways differ significantly between infected and healthy trees. In particular, we observed differences in sugar metabolites. The finding provides that sucrose metabolites are important for colonization of E. amylovora in host tissue. Our results provide fundamental information on the microbial community structures between E. amylovora infected and uninfected trees, which will contribute to developing novel control strategies for the fire blight disease.

• The Plant Pathology Journal
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• 제33권4호
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• pp.434-439
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• 2017

Incidence rates of diseases in kiwiberry orchards were investigated monthly from late June to late September in Gwangyang and Boseong in 2015 and 2016. The impact of postharvest fruit rot was investigated during ripening after harvest. Bacterial canker was only observed on one single tree in 2015, but black rot, powdery mildew, leaf spot and blight, and postharvest fruit rot diseases were problematic throughout the study period in both 2015 and 2016. Incidence rates of the diseases varied with kiwiberry cultivar, region and sampling time. Incidence rates of powdery mildew, leaf spot and blight diseases increased significantly during the late growing stages near fruit harvest, while black rot peaked in late August. Incidence rate of postharvest fruit rot on fruit without fruit stalks was less than half of fruit with fruit stalks, regardless of kiwiberry cultivars. Among the four cultivars, Mansu was relatively resistant to black rot and postharvest fruit rot diseases. In our knowledge, this is the first report of various potential pathogens of kiwiberry in Korea.

• 한국응용곤충학회지
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• 제9권1호
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• pp.7-13
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• 1970

1. 본 병에 강한 감수성품종인 금남풍을 사용하였고, Xanthomonas oyzae 6526 균주를 반합성감자배양기에 이식, $28^{\circ}C$에 3일간 사면배양한 뒤 균부유액을 만들어 상엽 상단부에 단침접종하고 14일 뒤에 확대된 병반길이를 조사하였다. 시험구설정은 3요소를 각각 무비$\cdot$표준비$\cdot$배비의 3개 수준으로 시비하여 총 27개구를 설정하고 3반복 임의배치하였다. 2. 질소질비료는 인산$\cdot$가리의 시용량에 크게 좌우되지 않았고 증시할 수록 발병이 심하였다. 3. 인산은 표준량시용하였을 때만 다소 발병억제효과의 경향이 있었으나 배비하게 되면 오히려 무비구보다도 터 발병이 촉진되었다. 4. 가리를 표준양시용하였을에 발병이 현저히 줄어들으나 시용량과 비례하지 않았고 배비하면 인산에서 처럼 다시 발병이 촉진되었다. 5. 출수시기가 늦어질 수록, 그리고 수수가 많을수록 발병이 심하였다. 6. 삼요소를 다같이 표준량시용하였을 때가 가장 발병이 적었는데, 작물의 영양조성은 비료의 종류, 시용량, 시용방법에 따라 좌우되며 발병도 기주식물의 조성과 밀접한 관계가 있으므로 시비법을 적절히 조절하면 본 병의 피해를 많이 감소시킬 수 있을 것으로 기대된다.

• 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.

• The Plant Pathology Journal
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• 제39권4호
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• pp.409-416
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• 2023

Bacterial leaf blight of carrots caused by Xanthomonas hortorum pv. carotae (Xhc) is an important worldwide seed-borne disease. In 2012 and 2013, symptoms similar to bacterial leaf blight were found in carrot farms in Jeju Island, Korea. The phenotypic characteristics of the Korean isolation strains were similar to the type strain of Xhc. Pathogenicity showed symptoms on the 14th day after inoculation on carrot plants. Identification by genetic method was multi-position sequencing of the isolated strain JJ2001 was performed using four genes (danK, gyrB, fyuA, and rpoD). The isolated strain was confirmed to be most similar to Xhc M081. Furthermore, in order to analyze the genetic characteristics of the isolated strain, whole genome analysis was performed through the next-generation sequencing method. The draft genome size of JJ2001 is 5,443,372 bp, which contains 63.57% of G + C and has 4,547 open reading frames. Specifically, the classification of pathovar can be confirmed to be similar to that of the host lineage. Plant pathogenic factors and determinants of the majority of the secretion system are conserved in strain JJ2001. This genetic information enables detailed comparative analysis in the pathovar stage of pathogenic bacteria. Furthermore, these findings provide basic data for the distribution and diagnosis of Xanthomonas hortorum pv. carotae, a major plant pathogen that infects carrots in Korea.