• 식물병연구
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• 제10권4호
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• pp.290-296
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• 2004

꽃썩음병은 참다래에 가장 중요한 병해 중 하나이다. 꽃썩음병은 5월말 개화기에 발생하는데, 개화기에 강우가 겹칠 경우 꽃썩음병이 대발생하여 참다래 수량에 심각한 감수를 초래한다. 병든 꽃봉오리로부터 분리된 꽃썩음병 병원세균은 생리 생화학적 특정과 병원성 검정 실험 결과 Pseudomonas syringae pv. syringae로 동정되었다. 참다래 과수원에서 죽은 과경지, 전정 가지, 낙엽과 토양 등이 참다래 꽃썩음병균의 중요한 월동 부위이고, 참다래 나무에 있는 신초눈, 주간, 주지, 가지 등도 전염원의 월동처를 제공해준다. 월동부위 중에서 죽은 과경지에 가장 높은 밀도의 전염원이 검출되었다. 참다래에 꽃썩음병을 일으킬 수 있는 발병 최소농도는 $10^4$cfu/ml로 추정되었으며, 꽃썩음병균의 최적 생장 온도는 $20{\sim}25^{\circ}C$였다. 평균 기온이 참다래 꽃썩음병 생육적온과 일치하는 5${\sim}$6월에 월동 부위에서 가장 높은 밀도의 전염원이 검출되었다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.54-54
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• 2015

Crops lack genetic resistance to most necrotrophic soil-borne pathogens and parasitic nematodes that are ubiquitous in agroecosystems worldwide. To overcome this disadvantage, plants recruit and nurture specific group of antagonistic microorganisms from the soil microbiome to defend their roots against pathogens and other pests. The best example of this microbe-based defense of roots is observed in disease-suppressive soils in which the suppressiveness is induced by continuously growing crops that are susceptible to a pathogen. Suppressive soils occur globally yet the microbial basis of most is still poorly described. Fusarium wilt, caused by Fusarium oxysporum f. sp. fragariae is a major disease of strawberry and is naturally suppressed in Korean fields that have undergone continuous strawberry monoculture. Here we show that members of the genus Streptomyces are the specific bacterial components of the microbiome responsible for the suppressiveness that controls Fusarium wilt of strawberry. Furthermore, genome sequencing revealed that Streptomyces griseus, which produces a novel thiopetide antibiotic, is the principal species involved in the suppressiveness. Finally, chemical-genetic studies demonstrated that S. griseus antagonizes F. oxysporum by interfering with fungal cell wall synthesis. An attack by F. oxysporum initiates a defensive "cry for help" by strawberry root and the mustering of microbial defenses led by Streptomyces. These results provide a model for future studies to elucidate the basis of microbially-based defense systems and soil suppressiveness from the field to the molecular level.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.136.1-136
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• 2003

Bacterial grain rot by Burkholderia gluae cause severe damage in seedling and grain of rice after heading season. This seed-borne pathogen play a role as first infection agent that could be cause disease following cropping season. Until now the direct isolation of the bacteria has some trouble by interference of other bacteria existed inside seed. This study established convenient identification method as simple isolation with KB medium from seed showing symptom and using PCR identification. By this isolation method, B. glumae was isolated from 40 to 50％ in brown rice and inner hull, however, there were saprophytic bacteria and fungi outer hull. In PCR identification with Ogf4 and Ogr3 primer to these 25 isolates, the amplified products were presented in all of the collections but not in 10 saprophytic germs. The isolation rate was constant to 3 months stored seeds. This result provide a rapid and convenient isolation and identification of B. glumae.

• The Plant Pathology Journal
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• 제21권1호
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• pp.39-46
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• 2005

The promoter region flanking the 5’ CAZFP1 coding region was isolated from the genomic DNA of Capsicum annuum. To identify the upstream region of the CAZFP1 gene required for promoter activity, a series of CAZFP1 promoter deletion derivatives was created. Each deletion construct was analyzed by Agrobacterium-mediated transient transformation in tobacco leaves after infection by Pseudomonas syringae pv. tabaci, or treatment with methyl jasmonate (MeJA), ethylene, abscisic acid (ABA), salicylic acid (SA), cold and wounding. Promoter fragments of 685 bp or longer showed 7-fold or greater induction after P. s. pv. tabaci infection and MeJA treatment. The CAZFP1 full-length promoter (-999 bp) also showed 6-fold induction in response to ethylene. The transiently transformed tobacco leaves with the CAZFP1 full length promoter fused-GUS gene showed more than 5-fold induction in response to SA, ABA and cold. These results suggest that the CAZFP1 promoter contains responsive elements for pathogen, MeJA, ethylene, SA, ABA and cold.

• 식물병연구
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• 제29권1호
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• pp.64-71
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• 2023

In October 2021, soft rot disease seriously affected radish crop in Dangjin, Chungcheongnam-do, Korea. The infected radishes were stunted and turned dark green, with yellowish leaf foliage. A slimy, wet, and decayed pith region was observed in the infected roots. The bacterial strain KNUB-03-21 was isolated from infected roots. The biochemical and morphological characteristics of the isolate were similar to those of Pectobacterium brasiliense. Phylogenetic analysis based on the sequences of the 16S rRNA region and the concatenated DNA polymerase III subunit tau (dnaX), leucine-tRNA ligase (leuS), and recombinase subunit A (recA) genes confirmed that the isolate is a novel strain of P. brasiliense. Artificial inoculation of radish with P. brasiliense KNUB-03-21 resulted in soft rot symptoms similar to those observed in infected radish in the field; subsequently, P. brasiliense KNUB-03-21 was reisolated and reidentified. To our knowledge, this is the first report of P. brasiliense as a causal pathogen of radish soft rot in Korea.

• The Plant Pathology Journal
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• 제40권2호
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• pp.139-150
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• 2024

Huanglongbing (HLB) is a disease caused by the phloem-limited Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry worldwide. To date, only indirect strategies have been implemented to eradicate HLB. Included among these is the population control of the psyllid vector (Diaphorina citri), which usually provides inconsistent results. Even though strategies for direct CLas suppression seem a priori more promising, only a handful of reports have been focused on a confrontation of the pathogen. Recent developments in polymer chemistry have allowed the design of polycationic self-assembled block copolymers with outstanding antibacterial capabilities. Here, we report the use of polymeric nano-sized bactericide particles (PNB) to control CLas directly in the phloem vasculature. The field experiments were performed in Rioverde, San Luis Potosí, and is one of the most important citrusproducing regions in Mexico. An average 52% reduction in the bacterial population was produced when PNB was injected directly into the trunk of 20 infected trees, although, in some cases, reduction levels reached 97%. These results position PNB as a novel and promising nanotechnological tool for citrus crop protection against CLas and other related pathogens.

• 한국식물병리학회지
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• 제1권1호
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• pp.61-66
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• 1985

벼 흰빛잎마름병균주 Q7472와 Q7502의 항혈청을 사용하여 우리나라에서 수집한 벼 흰빛잎마름병균의 혈청형을 한천gel내 확산법에 의해 분류한 결과, 71균주중 65균주가 혈정형 A형, 5균주가 B-I, 1균주가 B-II형에 속하였다. 혈청형A에 속하는 균주는 $0.1-1\%$의 $CaCl_2$용액에서 자기의집이 거의 일어나지 않았으나 혈청형 B-I과 B-II에 속하는 균주는 심한 자기의집이 일어나 혈청형과 자기의집 사이에는 밀접한 관계가 있었다. 흰빛잎마름병균은 혈청학적 방법에 의해 쉽게 검색될 뿐만 아니라 한천gel내 확산법에 의해 벼 세균성줄무늬병균인 X.campestris pv. olyzicola의 부생세균인 E. herbicola와도 쉽게 구별되었다. 흰빛잎마름병균 검출은 병반을 NaCl용액에 넣은 후에 착압하거나 $100^{\circ}C$에서 1시간 열처리 후 착압한 즙액을 한천gel내 확산법에 의해 항혈청과 반응시킴으로써 가능하였으며, 병반이 적을때는 PSA배지에서 배양한 후 사용하면 효과적이었다.

• The Plant Pathology Journal
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• 제36권5호
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• pp.440-449
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• 2020

The purpose of this study was to analyze the genetic and pathogenic characteristics of Ralstonia pseudosolanacearum in roses in Korea, and to examine the similarities and differences between Korean isolates and the first-reported European strains. Between 2017 and 2019, seventeen isolates from rose plants were identified as R. pseudosolanacearum using Ralstonia-specific primers. All 17 isolates were identified as race 1 using race-specific primers, and were confirmed as biovar 3 due to their ability to utilize carbon sources. Multiplex PCR using phylotype discriminating specific primers identified the 17 isolates as phylotype I. Sequevar comparison with reference sequevars using the sequences of the egl, mutS, and fliC genes, and only the egl gene, revealed that the strains evaluated in this study corresponded to sequevar I-33. The pathogenicity in roses differed depending on the rose cultivars. The different methods used for the genetic characterization of R. pseudosolanacearum indicate that the 17 rose bacterial wilt isolates had the same genetic characteristics. The lack of genetic variation in these isolates indicates their recent introduction from other countries (likely European countries). Therefore, appropriate quarantine and control measures should be taken in order to avoid further increases in the pathogenicity and/or secondary host range of R. pseudosolanacearum through genetic mutation.

• Journal of Microbiology and Biotechnology
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• 제29권5호
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• pp.785-793
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• 2019

Black rot caused by Xanthomonas campestris pv. campestris (Xcc) is the most damaging disease in Brassica crops around the world. In this study, we developed a molecular marker specific to Xcc race 5. To do this, the available whole genome sequences of Xcc races/strains and Xc subspecies were aligned and identified a highly variable genomic region (XccR5-89.2). Subsequently, a primer set covering the 'XccR5-89.2' region was designed and tested against the genomic DNA of Xcc races/strains, Xc subspecies and other plant-infecting bacterial strains (Pseudomonas syringae pv. maculicola and Erwinia carotovora subsp. carotovora). The results showed that the 'XccR5-89.2' primer pair amplified a 2,172-bp fragment specific to Xcc race 5. Moreover, they also amplified a 1,515-bp fragment for Xcc race 1 and an over 3,000-bp fragment for Xcc race 3. However, they did not amplify any fragments from the remaining Xcc races/strains, subspecies or other bacterial strains. The 'XccR5-89.2' primer pair was further PCR amplified from race-unknown Xcc strains and ICMP8 was identified as race 5 among nine race-unknown Xcc strains. Further cloning and sequencing of the bands amplified from race 5 and ICMP8 with 'XccR5-89.2' primers revealed both carrying identical sequences. The results showed that the 'XccR5-89.2' marker can effectively and proficiently detect, and identify Xcc race 5 from Xcc races/strains, subspecies and other plant-infecting bacteria. To our knowledge, this is the first report for an Xcc race 5-specific molecular marker.

• 한국동물위생학회지
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• 제41권3호
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• pp.203-210
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• 2018

Pasteurella multocida is an opportunistic organism that plays a significant role in porcine respiratory disease complex (PRDC). In the current study, we provide nationwide information of P. multocida isolates from pneumonic lungs of slaughter pigs by determining their prevalence, subspecies, biovars, capsular types, virulence-associated genes, and minimum inhibitory concentrations. P. multocida was the second most frequently confirmed (19.2%) bacterial pathogen and most of the isolates (88.9%) showed simultaneous infection with other respiratory pathogens, especially Mycoplasma hyopneumoniae (63.3%, P<0.001) and porcine circovirus type 2 (53.3%, P=0.0205). Of 42 isolates investigated, 41 (97.6%) were identified as P. multocida subspecies multocida, and only one isolate was identified as subspecies septica (biovar 5). All the isolates were capsular type A and the most prevalent biovar was biovar 3 (40.5%), followed by biovar 2 (31.0%). Comparing virulence-associated genes and biovars, all biovar 2 isolates exhibited $hgbB^-pfhA^+$ (P<0.001); all biovar 3 (P=0.0002) and biovar 13 (P=0.0063) isolates presented $hgbB^+pfhA^-$. Additionally, all biovar 2 (P=0.0037) isolates and most of biovar 3 (P=0.0265) isolates harbored tadD. P. multocida showed the highest resistance levels to oxytetracycline (73.8%), followed by florfenicol (11.9%). Continuous monitoring is required for surveillance of the antimicrobial resistance and new emerging strains of P. multocida in slaughter lines.