• Title/Summary/Keyword: Pseudomonas chlororaphis O6

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A two-component sensor kinase (GacS) mediated signal transduction pathway involved in production of antifungal compounds in Pseudomonas chlororaphis O6.

  • Kang, Beom-Ryong;Lee, Jung-Hoon;Kim, Hyun-Jung;Cho, Baik-Ho;Kim, Young-Cheol
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • 2003.10a
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    • pp.99.1-100
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    • 2003

  • E. intermedium Blocontrol activity of a P. chlororaphis rhizobacteium O6, depends to the synthesis of extracellular secondary metabolites and exoenzymes, thought to antagonize the pathogenicity of a variety of phytopathogenic fungi. The production of secondary metabolites and exoenzymes in O6, depends essentially on the GacS-mediated signal transduction pathway, which activates largely unknown signal transduction pathway. To exploit the GacS-mediated signal transdcution pathway involved in activation of ph genes that are necessary for biosynthesis of phenazine from P. chlororaphis O6, we cloned and sequenced the phz operon, rpoS gene encoding stationary specific sigma factor, ppx gene encoding polyphosphatase, and lon gene encoding ion protease. Expression of each gene in wild type and GacS mutant were analyzed by RT-PCR. Transcripts from rpoS, phzI enconing acylhomoserine lactone (AHL) synthase, and ph structural genes in the GacS mutant were reduced in each of these growth phases compared to the wild type. The GacS or Lon mutant was found to be deficient in the production of phenzines, exoenzymes, and the acylhomoserine lactone. These mutants were not complemented by ph operon and addition of exogenous AHL. These results indicate that the GacS global regulatory systems controls phenazine production at multiple levels. Future research will focus to identifying the GacS-mediated regulatory cascade involving in production of phenazine in P. chlororaphis.

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The Sensor Kinase GacS Negatively Regulates Flagellar Formation and Motility in a Biocontrol Bacterium, Pseudomonas chlororaphis O6

  • Kim, Ji Soo;Kim, Yong Hwan;Anderson, Anne J.;Kim, Young Cheol
    • The Plant Pathology Journal
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    • v.30 no.2
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    • pp.215-219
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    • 2014

  • The GacS/GacA two component system regulates various traits related to the biocontrol potential of plant-associated pseudomonads. The role of the sensor kinase, GacS, differs between strains in regulation of motility. In this study, we determined how a gacS mutation changed cell morphology and motility in Pseudomonas chlororaphis O6. The gacS mutant cells were elongated in stationary-phase compared to the wild type and the complemented gacS mutant, but cells did not differ in length in logarithmic phase. The gacS mutant had a two-fold increase in the number of flagella compared with the wild type strain; flagella number was restored to that of the wild type in the complemented gacS mutant. The more highly flagellated gacS mutant cells had greater swimming motilities than that of the wild type strain. Enhanced flagella formation in the gacS mutant correlated with increased expression of three genes, fleQ, fliQ and flhF, involved in flagellar formation. Expression of these genes in the complemented gacS mutant was similar to that of the wild type. These findings show that this root-colonizing pseudomonad adjusts flagella formation and cell morphology in stationary-phase using GacS as a major regulator.

  • https://doi.org/10.5423/PPJ.NT.11.2013.0109 인용 PDF KSCI

Bacterial determinants involved in the induction of systemic resistance ana plant growth promotion in tobacco by Pseudomonas chlororaphis O6.

  • Han, Song-Hee;Cho, Baik-Ho;Kim, Young-Cheol
    • Proceedings of the Korean Society of Plant Pathology Conference
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    • 2003.10a
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    • pp.101.2-102
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    • 2003

  • The ability of P. chlororaphis O6 to induce resistance to Erwinia carotovora subsp. carotovara SCCI and to promote growth in tobacco was demonstrated in microtiter assays on plants pre-inoculated at the root level with the bacteria before challenge with the leaf pathogen. To identify th bacterial determinants involved in induced systemic resistance and plant growth promotion, cell culture of O6 grown in King's medium B was fractionated with organic solvents and purified using various columns. in vivo and in vitro assays with samples from successive fractionation steps of the O6 supernatant led to the conclusion that antibacterial compounds were observed in aqueous layer, and to the isolation of fractions containing metabolites that retained most of the resistance-inducing activity (70：30, methanol：water) and the plant growth promotion (80：20 and 90：10, methanol：water) after ODS column chromatography. Although these molecules remain to be purified further and structurally characterized, its isolation is an addition to the range of determinants from plant growth-promoting rhizobacteria known to stimulate plant defence.

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