• The Plant Pathology Journal
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• 제28권1호
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• pp.68-74
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• 2012

Biocontrol microbes have mainly been screened among large collections of microorganisms $via.$ nutrient-rich $in$ $vitro$ assays to identify novel and effective isolates. However, thus far, isolates from only a few genera, mainly spore-forming bacilli, have been commercially developed. In order to isolate field-effective biocontrol microbes, we screened for more than 200 oligotrophic bacterial strains, isolated from rhizospheres of various soil samples in Korea, which induced systemic resistance against the soft-rot disease caused by $Pectobacterium$ $carotovorum$ SCC1; we subsequently conducted in $planta$ bioassay screening. Two oligotrophic bacterial strains were selected for induced systemic disease resistance against the $Tobacco$ $Mosaic$ $Virus$ and the gray mold disease caused by $Botrytis$ $cinerea$. The oligotrophic bacterial strains were identified as $Pseudomonas$ $manteilii$ B001 and $Bacillus$ $cereus$ C003 by biochemical analysis and the phylogenetic analysis of the 16S rRNA sequence. These bacterial strains did not exhibit any antifungal activities against plant pathogenic fungi but evidenced several other beneficial biocontrol traits, including phosphate solubilization and gelatin utilization. Collectively, our results indicate that the isolated oligotrophic bacterial strains possessing induced systemic disease resistance could provide useful tools as effective biopesticides and might be successfully used as cost-effective and preventive biocontrol agents in the field.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.586-593
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• 2007

Seed coating by a phenazine-producing bacterium, Pseudomonas chlororaphis O6, induced dose-dependent inhibition of germination in wheat and barley seeds, but did not inhibit germination of rice or cucumber seeds. In wheat seedlings grown from inoculated seeds, phenazine production levels near the seed were higher than in the roots. Deletion of the gacS gene reduced transcription from the genes required for phenazine synthesis, the regulatory phzI gene and the biosynthetic phzA gene. The inhibition of seed germination and the induction of systemic disease resistance against a bacterial soft-rot pathogen, Erwinia carotovora subsp. carotovora, were impaired in the gacS and phzA mutants of P chlororaphis O6. Culture filtrates of the gacS and phzA mutants of P. chlororaphis O6 did not inhibit seed germination of wheat, whereas that of the wild-type was inhibitory. Our results showed that the production of phenazines by P. chlororaphis O6 was correlated with reduced germination of barley and wheat seeds, and the level of systemic resistance in tobacco against E. carotovora.

• International Journal of Industrial Entomology and Biomaterials
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• 제35권2호
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• pp.63-70
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• 2017

Native fluorescent pseudomonas bacteria were isolated from rhizosphere soil of mulberry and were evaluated against powdery mildew. In vitro conidial germination study showed significant (P<0.05) variation in conidial germination by bacterial strains Pf1 and Pf3. Mildew incidence was significantly varied due to treatment with various pseudomonas strains in vivo. Significantly (P<0.05) less mildew incidence was in plants treated with the bacterial strain Pf1 (9.11%) followed by Pf3 (13.48%) controlling 69.40% and 54.75% respectively compared with untreated control. Similarly, mildew severity was least (8.51%) in plants treated with strain Pf1 followed by Pf5 (9.23%) and Pf3 (9.72%) controlling the severity by 84.51%, 77.01% and 71.96% respectively compared with control. The bacterial strains significantly influenced biochemical constituents such as chlorophyll, protein and soluble sugar content of the mulberry leaf. Similarly, bacterial strains significantly increased the activity of the peroxidase (PO) and Polyphenol oxydase (PPO) activity from $7^{th}$ day up to the $28^{th}$ day after treatment. The strain Pf1, Pf3 and Pf5 exhibited a marked enhancement in the peroxidase at different periods of infection. Significant (P<0.01) negative correlation was found between powdery mildew severity with phenol content ($R^2=0.67$) as well as peroxidase ($R^2=0.92$) and polyphenol oxidase ($R^2=0.72$) activity thus confirms induction of systemic resistance in mulberry by pseudomonas bacteria. The study shows scope for exploration of rhizosphere fluorescent pseudomonas bacteria for induction of systemic resistance in mulberry to contain powdery mildew disease effectively.

• International Journal of Industrial Entomology and Biomaterials
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• 제6권1호
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• pp.11-14
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• 2003

Systemic fungicides viz., Bavistin and Beyleton are reported to have curative effect against the infection of Beauveria bassiana in silkworm Bombyx mori L. To understand the influence of the systemic fungicides on the disease suppression/development, hematological studies were carried out. There was an increase in the percent total hemocyte count, granulocyte and plasmatocyte in silkworm treated with the systemic fungicides. It possibly indicates the influence of systemic fungicide on the hemocyte mediated defense system leading to the higher resistance and suppression of disease development.

• 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.

• Mycobiology
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• 제39권4호
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• pp.290-298
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• 2011

The ability of benzothiadiazole (BTH) and/or humic acid (HA) used as seed soaking to induce systemic resistance against a pathogenic strain of Fusarium oxysporum was examined in four soybean cultivars under greenhouse conditions. Alone and in combination the inducers were able to protect soybean plants against damping-off and wilt diseases compared with check treatment. These results were confirmed under field conditions in two different locations (Minia and New Valley governorates). The tested treatments significantly reduced damping-off and wilt diseases and increased growth parameters, except the number of branches per plant and also increased seed yield. Application of BTH (0.25 g/L) + HA (4 g/L) was the most potent in this respect. Soybean seed soaking in BTH + HA produced the highest activities of the testes of oxidative enzymes followed by BTH in the four soybean cultivars. HA treatment resulted in the lowest increases of these oxidative enzymes. Similar results were obtained with total phenol but HA increased total phenol more than did BTH in all tested cultivars.

• 환경생물
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• 제38권4호
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• pp.724-732
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• 2020

본 연구에서는 기 선발한 Enterobacter asburiae ObRS-5 균주를 1×10⁸ cfu mL^-1 농도로 고추에 관주 처리했을 때 Phytophthora capsici에 의한 고추역병을 74.6% 방제하는 효과가 있었다. E. asburiae ObRS-5 균주에 의한 고추역병 방제 메커니즘을 확인하기 위해 고추의 PR1, PR4 및 PR10 유전자를 특이적으로 증폭하는 프라이머를 이용하여 quantitative PCR을 수행하였다. 그 결과 E. asburiae ObRS-5 균주를 처리한 고추에서 대조구와 비교하여 상기 세 가지 유전자의 발현이 모두 높은 수준을 유지하였다. 또한 E. asburiae ObRS-5 균주는 고추의 생육을 억제하지 않으면서 ISR 반응을 유도하는 것으로 나타났다. 이러한 결과를 통하여 P. capsici이 침입할 때 E. asburiae ObRS-5 균주가 매개하는 ISR 메커니즘을 통해 Phytophthora 역병의 제어가 가능한 것으로 사료된다.

• IMMUNE NETWORK
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• 제22권1호
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• pp.13.1-13.14
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• 2022

Chronic inflammation plays a critical role in the development of obesity-associated metabolic disorders such as insulin resistance. Obesity alters the microenvironment of adipose tissue and the intestines from anti-inflammatory to pro-inflammatory, which promotes low grade systemic inflammation and insulin resistance in obese mice. Various T cell subsets either help maintain metabolic homeostasis in healthy states or contribute to obesity-associated metabolic syndromes. In this review, we will discuss the T cell subsets that reside in adipose tissue and intestines and their role in the development of obesity-induced systemic inflammation.