• The Plant Pathology Journal
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• 제16권5호
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• pp.264-268
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• 2000

A fluorescent material was accumulated in inoculated leaves showing necrotic local lesions of tobacco plants with N gene, Nicotiana tabacum cvs. Xanthi-nc NN, Samsun NN, Burley 21 and KF 114, and N. glutinosa, and Datura stramonium at the early growth stages by the inoculation of Tobacco mosaic virus (TMV). It was identified as a coumarin phytoalexin, scopoletin. Although the material was most prominently produced in TMV-inoculated tobacco leaves with local necrotic lesions, its accumulation was also noted in uninoculated leaves of TMV-inoculated plants. Its accumulation was somewhat greater in high resistance-induced leaves than low resistance-induced and intact leaves. Scopoletin treatment induced the expression of a pathogenesis-related protein, PR-1, prominently at the concentration of 500 or 1000 ${\mu}$g/ml. This suggests that scopoletin is a phytoalexin abundantly accumulating in N gene-containing resistant plants in response to TMV infection, and may be related to hypersensitive responses (HR) and systemic acquired resistance (SAR) in the resistant tobacco plants.

• 농약과학회지
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• 제15권4호
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• pp.485-489
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• 2011

Bacillus amyloliquefaciens strain EXTN-1 처리에 의해 생육촉진 효과와 함께 광범위한 식물 병 방제효과가 보고되었다. EXTN-1의 PGPR 효과는 생육초기에 PR-1a, PDF1.2 등의 저항성 관련 유전자 발현에 의한 oxidative burst의 증가나 SA, JA나 ethylene 대사에 의한 유도저항성의 발현에 기인한다. 이 연구의 목표는 B. amyloliquefaciens EXTN-1가 기존에 보고된 다른 작물의 경우에서와 마찬가지로 벼의 생육촉진이나 벼줄무늬잎마름병에 대한 저항성에 관여하는지를 확인하기 위해 수행되었다. 벼 종자를 B. amyloliquefaciens EXTN-1에 침지한 후 파종하였을 때 생육촉진 효과와 병에 대한 저항성 발현이 확인되었다. B. amyloliquefaciens EXTN-1을 처리한 30일묘에서 벼의 초장, 생물중, 뿌리길이는 무처리구에 비해 각각 12.6%, 9.8%, 16.0% 증가하여 PGPR 효과가 나타남을 확인할 수 있었다. RSV 접종구에서도 B. amyloliquefaciens EXTN-1 20일묘는 초장, 생물중, 뿌리길이는 무처리구에 비해 각각 12.6%, 9.8%, 16.0% 증가하였다. 유도저항성 발현효과는 감수성 품종에서 저항성 품종에서 상대적으로 뚜렷하게 나타났다.

• The Plant Pathology Journal
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• 제25권4호
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• pp.389-399
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• 2009

A group of beneficial plant bacteria has been shown to increase crop growth referring to as plant growth-promoting rhizobacteria (PGPR). PGPR can decrease plant disease directly, through the production of antagonistic compounds, and indirectly, through the elicitation of a plant defense response termed induced systemic resistance (ISR). While the mechanism of PGPR-elicited ISR has been studied extensively in the model plant Arabidopsis, it is less well characterized in crop plants such as pepper. In an effort to better understand the mechanism of ISR in crop plants, we investigated the induction of ISR by Bacillus cereus strain BS107 against Xanthomonas axonopodis pv. vesicatoria in pepper leaves. We focused on the priming effect of B. cereus strain BS107 on plant defense genes as an ISR mechanism. Of ten known pepper defense genes that were previously reported to be involved in pathogen defense signaling, the expression of Capsicum annum pathogenesis-protein 4 and CaPR1 was systemically primed by the application of strain BS107 onto pepper roots confirming by quantitative-reverse transcriptase PCR. Our results provide novel genetic evidence of the priming effect of a rhizobacterium on the expression of pepper defense genes involved in ISR.

• 식물병연구
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• 제20권3호
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• pp.182-188
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• 2014

Because bacterial isolates from only a few genera have been developed commercially as biopesticides, discovery and characterization of novel bacterial strains will be a key to market expansion. Our previous screen using plant bioassays identified 24 novel biocontrol isolates representing 12 different genera. In this study, we characterized the 3 isolates showing the best biocontrol activities. The isolates were Pantoea dispersa WCU35, Proteus myxofaciens WCU244, and Exiguobacterium acetylicum WCU292 based on 16S rRNA sequence analysis. The isolates showed differential production of extracellular enzymes, antimicrobial activity against various fungal or bacterial plant pathogens, and induced systemic resistance activity against tomato gray mold disease caused by Botrytis cinerea. E. acetylicum WCU292 lacked strong in vitro antimicrobial activity against plant pathogens, but induced systemic resistance against tomato gray mold disease. These results confirm that the trait of biological control is found in a wide variety of bacterial genera.

• Journal of Plant Biotechnology
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• 제43권1호
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• pp.99-103
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• 2016

고려인삼은 다년생 약용작물로써 재배 특성상 인삼에서 다양한 질병들의 효과적인 방제시스템의 개발은 인삼의 생산량 증대에 매우 중요한 요소이다. 최근 지속가능한 농업의 실현을 위한 식물의 유도저항성(ISR)과 유용미생물의 항생제 효과를 이용한 친환경 생물학적 방제 기법이 주목을 받고 있다. 하지만 인삼의 유도정항성을 정확하게 판단할 수 있는 기법은 아직까지 거의 연구되어 있지 않다. 본 논문에서는 인삼의 유묘를 이용한 무병주 기내배양 시스템을 개발하였고, BTH에 의해 유도되는 인삼의 유도저항성을 통한 잿빛곰팡이병과 탄저병에 대한 방제효과를 검증하였다. 인삼유묘에 유도저항성을 위해 뿌리에 직접적으로 BTH를 처리하는 관주처리 방법에 비해, 잎에 직접적으로 살포하는 엽면시비 방법이 효과적으로 두 곰팡이성 병원균에 대한 방제효과가 높게 나타났다. BTH처리 인삼유묘에 탄저병원균을 처리하였을 때 인삼의 병원균 침입에 의해 급격히 발현이 증대되는 PgPR10과 PgCAT 유전자의 발현이 급속하게 증대되는 현상을 확인하였다. 본 연구를 통해 개발된 시스템은 향후 친환경적으로 이용될 수 있는 다양한 생물학적 방제제의 효과를 검정하고 활용하는데 매우 유용하게 이용될 수 있을 것이다.

• 한국자원식물학회지
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• 제23권3호
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• pp.248-255
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• 2010

We previously demonstrated that root colonization of the rhizobacterium, Pseudomonas chlororaphis O6, induced expression of a galactinol synthase gene (CsGolS1), and resulting galactinol conferred induced systemic resistance (ISR) against fungal and bacterial pathogens in cucumber leaves. To examine the role of galactinol on ISR, drought or high salt stress, we obtained T-DNA insertion Arabidopsis mutants at the AtGolS1 gene, an ortholog of the CsGolS1 gene. The T-DNA insertion mutant compromised resistance induced by the O6 colonization against Erwinia carotovora. Pharmaceutical application of 0.5 - 5 mM galactinol on roots was sufficient to elicit ISR in wild-type Arabidopsis against infection with E. carotovora. The involvement of jasmonic acid (JA) signaling on the ISR was validated to detect increased expression of the indicator gene PDF1.2. The T-DNA insertion mutant also compromised tolerance by increasing galactinol content in the O6-colonized plant against drought or high salt stresses. Taken together, our results indicate that primed expression of the galactinol synthase gene AtGolS1in the O6-colonized plants can play a critical role in the ISR against infection with E. carotovora, and in the tolerance to drought or high salt stresses.

• The Plant Pathology Journal
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• 제23권3호
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• pp.203-209
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• 2007

Infection structures were observed using a fluorescence microscope at the penetration sites on the leaves of potato plants pre-inoculated with the bacterial strains Pseudomonas putida TRL2-3, Micrococcus luteus TRK2-2, and Flexibacteraceae bacterium MRL412, which mediated an induced systemic resistance on potato plants against late blight disease caused by Phytophthora infestans. In order to compare the infection structures on the leaves expressing systemic acquired resistance, the leaves of potato plants pre-treated with DL-3-amino butyric acid (BABA) were also observed after challenge inoculation with the same pathogen. The infection structures were investigated. The total number of germination and appressorium formation of P. infestans were counted. Furthermore, the frequencies of fluorescent epidermal cells at the penetration sites, which indicate a defense response of plant cell, were estimated. There were no differences on the germination rates of the fungal cysts among the untreated control, BABA pre-treated, and bacterial strains pre-inoculated plants. However, appressorium formation was slightly decreased on the leaves of BABA pre-treated plants compared to those of untreated as well as bacterial strains pre-inoculated plants. Furthermore, the frequencies of fluorescent cells of BABA pre-treated and bacterial strains pre-inoculated were higher than that of untreated plants, indicating an active defense reaction of the host cells against the fungal attack. On the other hand, the pre-treatment with BABA caused a stronger fluorescent of epidermal cells at the penetration sites compared to the pre-inoculation with the bacterial strains. Interestingly, the frequency of fluorescent cells by BABA, however, was lower than that by the bacterial strains. Based on the results it is suggested that the infection structures showing resistance reaction on the leaves of potato plants were different between by pre-inoculation with bacterial strains and by pre-treatment with BABA against the late blight pathogen.

• The Plant Pathology Journal
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• 제32권5호
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• pp.481-488
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• 2016

Dithiocarbamate fungicides such as maneb and mancozeb are widely used nonsystemic protectant fungicides to control various plant fungal diseases. Dithiocarbamate fungicides should be frequently applied to achieve optimal efficacy of disease control and avoid either decline in effectiveness or wash-off from leaf surface. Dithiocarbamates are of low resistance risk but have the potential to cause human neurological diseases. The objective of this study was to develop a strategy to effectively control plant disease with reduced use of dithiocarbamtes. Southern corn leaf blight was the model pathosystem for the investigation. When corn plants were drench-treated with Bacillus cereus C1L, a rhizobacterium able to induce systemic resistance in corn plants against southern leaf blight, frequency of spraying dithiocarbamate fungicides could be decreased. The treatment of B. cereus C1L was able to protect maize from southern leaf blight while residues of dithiocarbamates on leaf surface were too low to provide sufficient protection. On the other hand, frequent sprays of mancozeb slightly but significantly reduced growth of corn plants under natural conditions. In contrast, application of B. cereus C1L can significantly promote growth of corn plants whether sprayed with mancozeb or not. Our results provide the information that plant disease can be well controlled by rhizobacteria-mediated induced systemic resistance in combination with reduced but appropriate application of dithiocarbamate fungicides just before a heavy infection period. An appropriate use of rhizobacteria can enhance plant growth and help plants overcome negative effects caused by dithiocarbamates.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2005년도 추계 학술발표회
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• pp.33-34
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• 2005

• Journal of Microbiology and Biotechnology
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• 제21권7호
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• pp.686-696
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• 2011

To deal with pathogens, plants have evolved sophisticated mechanisms including constitutive and induced defense mechanisms. Phytohormones play important roles in plant growth and development, as well as in the systemic response induced by beneficial and pathogen microorganisms. In this work, we identified an Aspergillus ustus isolate that promotes growth and induces developmental changes in Solanum tuberosum and Arabidopsis thaliana. A. ustus inoculation on A. thaliana and S. tuberosum roots induced an increase in shoot and root growth, and lateral root and root hair numbers. Assays performed on Arabidopsis lines to measure reporter gene expression of auxin-induced/ repressed or cell cycle controlled genes (DR5 and CycB1, respectively) showed enhanced GUS activity, when compared with mock-inoculated seedlings. To determine the contribution of phytohormone signaling pathways in the effect elicited by A. ustus, we evaluated the response of a collection of hormone mutants of Arabidopsis defective in auxin, ethylene, cytokinin, or abscisic acid signaling to the inoculation with this fungus. All mutant lines inoculated with A. ustus showed increased biomass production, suggesting that these genes are not required to respond to this fungus. Moreover, we demonstrated that A. ustus synthesizes auxins and gibberellins in liquid cultures. In addition, A. ustus induced systemic resistance against the necrotrophic fungus Botrytis cinerea and the hemibiotrophic bacterium Pseudomonas syringae DC3000, probably through the induction of the expression of salicylic acid, jasmonic acid/ethylene, and camalexin defense-related genes in Arabidopsis.