• The Plant Pathology Journal
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• v.20 no.1
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• pp.7-12
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• 2004

An important recent advance in the field of plant-microbe interactions has been the cloning of genes that confer resistance to specific viruses, bacteria, fungi or insects. Disease resistance (R) genes encode proteins with predicted structural motifs consistent with them having roles in signal recognition and transduction. Plant disease resistance is the result of an innate host defense mechanism, which relies on the ability of plant to recognize pathogen invasion and efficiently mount defense responses. In tomato, resistance to the pathogen Pseudomonas syringae pv. tomato is mediated by the specific recognition between the tomato serine/threonine kinase Pto and bacterial protein AvrPto or AvrPtoB. This recognition event initiates signaling events that lead to defense responses including an oxidative burst, the hypersensitive response (HR), and expression of pathogenesis- related genes.

• Korean Journal of Plant Tissue Culture
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• v.21 no.2
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• pp.99-103
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• 1994

The herbicide bialaphos is a potent inhibitor of glutamine synthetase in higher plants. A bialaphos resistance (bar) gene encoding for an acetyltransferase was isolated from genomic DNA of Pseudomonas syringae pv tabaci. The bar gene was ligated to the binary vector pBI121. Pistils of tobacco plane were heated with the bar gene containing plasmid DNA at various times after pollination. When the treatment was applied at 30 and 40 h after pollination, a number of transgenic plants were obtained. Premary transformation (T$_{0}$ generation) and their progenies (T$_1$T$_2$) were resistant to both bialaphos and kanamycin at a dosage lathal to untransformed control plants. Stable integration of bar gene into chromosomal DNA was proven by Southern blot analysis of genomic DNA isolated from T$_1$progenies. These results show that the bialaphos resistant plane could be obtained by treatment to pistils with the exgenous bar gene through the fertilization cycle of tobacco.o.

• Journal of Microbiology and Biotechnology
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• v.29 no.5
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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.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.262-267
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• 2007

To access the natural product antibiotics produced by uncultured microorganisms, six cosmid libraries of DNA extracted directly from soil samples (environmental DNA, eDNA) were constructed and screened for the production of antibacterial active molecules. Of the approximately 60,000 clones screened, one antibacterial clone (YS92B) was detected. Ethyl acetate extracts of clone YS92B showed antibacterial activity against various pathogenic bacteria (Listeria monocytogenes, Bacillus subtilis, Pseudomonas syringae, Xanthomonas campestris pv. oryzae, Staphylococcus epidemis). Active constituents from cultures of YS92B were isolated and purified using a bioassay-guided fractionation against B. subtilis through a series of procedures (ethyl acetate extraction, Sephadex LH20 column chromatography, High Performance Liquid Chromatography). NMR (Nuclear Magnetic Resonance) spectral analysis of a major antibacterial active YS92B-VII indicated that it is a lauric acid linked to tyrosine. This report describes the characterization of antibacterially active long chain N-acyl derivatives of tyrosine that are produced by eDNA clones hosted in Escherichia coli from Korean soils.

• Research in Plant Disease
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• v.22 no.4
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• pp.217-226
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• 2016

Seasonal prevalence of bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) was investigated at a naturally infected orchard in Boseong, Jeonnam in 2014 and 2015. Stem canker began to occur in mid-February in 2014 and early March in 2015. Bacterial ooze was observed on canes, leaders and trunks until late May and gradually disappeared thereafter. The percentages of infected trees were 44.7% and 69.7% in 2014 and 2015, respectively. Trees with trunk canker in a previous year died in 2015. Leaf canker symptoms began to appear as brown spots with chlorotic halos in early May and irregular dark brown spots without halos were observed under humid conditions. Leaf canker progressed until mid-July in 2014 and late July in 2015. No Psa was detected from the leaf lesions on leaves thereafter, but new infection of Psa was observed on leaves in late October. Infected blossoms with blighted calyx were sometimes observed from mid-May. Optimal monitoring period to detect Psa was May when it could be easily detected from stems, leaves and blossoms. Disease cycle of bacterial canker of kiwifruit modified for Korea was proposed based on the seasonal prevalence of bacterial canker analyzed according to weather data in Boseong, Jeonnam over 2 years.

• Korean Journal of Plant Resources
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• v.20 no.2
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• pp.216-219
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• 2007

Root colonization by a rhizobacterium, Pseudomonas chlororaphis O6, elicited induced systemic resistance (ISR) in the leaves of cucumber plants against fungal and bacterial pathogens. To understand the role of unique genes during strain O6-mediated ISR, a suppressive subtractive hybridization method was undertaken and led to isolation of twenty-five distinct genes. The transcriptional levels of all the genes showed an increase much earlier under O6 treatment than in water control plants only after challenge with pathogen, while no difference detected on the plants without pathogen challenge. This suggests that O6-mediated ISR is associated with the priming phenomenon, an enhanced capacity for the rapid and effective activation of cellular defense responses after challenge inoculation.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.255-266
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• 2020

Plant immune responses can be triggered by chemicals, microbes, pathogens, insects, or abiotic stresses. In particular, induced systemic resistance (ISR) refers to the activation of the immune system due to a plant's interaction with beneficial microorganisms. The phenolic compound, 2,4-diacetylphloroglucinol (DAPG), which is produced by beneficial Pseudomonas spp., acts as an ISR elicitor, yet DAPG's mechanism in ISR remains unclear. In this study, transgenic Arabidopsis thaliana plants overexpressing the DAPG hydrolase gene (phlG) were generated to investigate the functioning of DAPG in ISR. DAPG was applied onto 3-week-old A. thaliana Col-0 and these primed plants showed resistance to the pathogens Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000. However, in the phlG transgenic A. thaliana, the ISR was not triggered against these pathogens. The DAPG-mediated ISR phenotype was impaired in transgenic A. thaliana plants overexpressing phlG, thus showing similar disease severity when compared to untreated control plants. Furthermore, the DAPG-treated A. thaliana Col-0 showed an increase in their gene expression levels of PDF1.2 and WRKY70 but this failed to occur in the phlG transgenic lines. Collectively, these experimental results indicate that jasmonic acid/ethylene signal-based defense system is effectively disabled in phlG transgenic A. thaliana lines.

• Research in Plant Disease
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• v.10 no.4
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• pp.297-303
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• 2004

Bacterial blossom blight of kiwifruit (Actinidia deliciosa) has been mainly controlled by antibiotics. Among 15 candidate chemicals, streptomycin sulfate oxytetracycline WP, streptomycin copper hydroxide WP and oxolinic acid WP were selected as preventive bactericides against bacterial blossom blight of kiwfruit through in vitro and in vivo test. Spray of streptomycin sulfate oxytetracycline WP and streptomycin copper hydroxide WP at flowering period was most effective in controlling bacterial blossom blight of kiwifruit. Among the various combinations of spray times at different spray periods, optimum spray program of the preventive bactericides for the control of bacterial blossom blight of kiwifruit was turned out to be 3 times application with 10 day-interval from early May during the flowering season of kiwifruits.

• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.896-900
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• 2006

Cytokinin has been known to act as a plant hormone to promote cell division and function in diverse processes in plant growth and development. Besides being produced in plants, it is also produced by various bacteria and fungi; however, its ecological significance is still unclear. In this report, we present an interesting finding that transzeatin riboside (tZR), a naturally occurring cytokinin compound, increased antibiotic production in many different streptomycetes, including Streptomyces coelicolor Ml3O, S. pristinaespiralis ATCC 25486, S. violaceoruber Tu22, S. anfibioticus ATCC l1891, and S. griseus IFO 13350. In vitro plate assays showed that the addition of 100 $\mu$M tZR increased the growth inhibition of Pseudomonas syringae pv. syringae, a plant pathogen, by S. griseus, a streptomycin producer. We suggest that cytokinin could act as a signaling molecule for antibiotic production in streptomycetes, a group of rhizosphere bacteria.

• Molecules and Cells
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• v.42 no.7
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• pp.503-511
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• 2019

As sessile organisms, plants have developed sophisticated system to defend themselves against microbial attack. Since plants do not have specialized immune cells, all plant cells appear to have the innate ability to recognize pathogens and turn on an appropriate defense response. The plant innate immune system has two major branches: PAMPs (pathogen associated molecular patterns)-triggered immunity (PTI) and effector-triggered immunity (ETI). The ability to discriminate between self and non-self is a fundamental feature of living organisms, and it is a prerequisite for the activation of plant defenses specific to microbial infection. Arabidopsis cells express receptors that detect extracellular molecules or structures of the microbes, which are called collectively PAMPs and activate PTI. However, nucleotidebinding site leucine-rich repeats (NB-LRR) proteins mediated ETI is induced by direct or indirect recognition of effector molecules encoded by avr genes. In Arabidopsis, plasmamembrane localized multifunctional protein RIN4 (RPM1-interacting protein 4) plays important role in both PTI and ETI. Previous studies have suggested that RIN4 functions as a negative regulator of PTI. In addition, many different bacterial effector proteins modify RIN4 to destabilize plant immunity and several NB-LRR proteins, including RPM1 (resistance to Pseudomonas syringae pv. maculicola 1), RPS2 (resistance to P. syringae 2) guard RIN4. This review summarizes the current studies that have described signaling mechanism of RIN4 function, modification of RIN4 by bacterial effectors and different interacting partner of RIN4 in defense related pathway. In addition, the emerging role of the RIN4 in plant physiology and intercellular signaling as it presents in exosomes will be discussed.