Phenazines and their role in biocontrol by <i>Pseudomonas</i> bacteria

Chin-A-Woeng, Thomas F. C.; Bloemberg, Guido V.; Lugtenberg, Ben

doi:10.1046/j.1469-8137.2003.00686.x

Cited by 319 publications

(159 citation statements)

References 283 publications

(339 reference statements)

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“…For example, the 2-hydroxy-phenazine-1 carboxylic acid produced by Pseudomonas aureofaciens is believed to destroy competing fungi through production of reactive oxygen species. 37 The expression of phenazine biosynthetic genes is regulated by multiple mechanisms, which are strongly influenced by environmental conditions. One of the primary factors governing phenazine production is population density, and in Pseudomonas aeruginosa, this dependency is affected by at least three quorumsensing systems.…”

Section: Carbon Source Regulation Of Antibiotic Production In Gram-nementioning

confidence: 99%

Carbon source regulation of antibiotic production

et al. 2010

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Section: Carbon Source Regulation Of Antibiotic Production In Gram-nementioning

confidence: 99%

Carbon source regulation of antibiotic production

et al. 2010

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“…Within the rhizosphere microbial populations are a group of plant-beneficial bacteria referred to as plant growth promoting rhizobacteria (PGPR). PGPR are beneficial to plants via nutrient acquisition (Rodriguez and Fraga, 1999;Dobbelaere et al, 2003;Ladha and Reddy, 2003), biocontrol (Walsh et al, 2001;Chin-A-Woeng et al, 2003), plant hormone-like production, lowering of plant ethylene level (Glick, 1995;Steenhoudt and Vanderleyden, 2000) and induction of systemic resistance (van Loon et al, 1998). Other beneficial microbial partners of the plant are the ubiquitous symbiotic arbuscular mycorrhizal fungi (AMF).…”

Section: Introductionmentioning

confidence: 99%

Plant growth stage, fertiliser management and bio-inoculation of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria affect the rhizobacterial community structure in rain-fed wheat fields

Roesti

Gaur

Johri

et al. 2006

Soil Biology and Biochemistry

192

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The goal of this study was first to assess the dynamics of the bacterial community during a growing season in three Indian rain-fed wheat fields which differ mainly through their fertilizer management and yield and then to study the effects of PGPR/AMF bio-inoculations on the bacterial community structure and wheat growth. The bacterial community structure of the rhizosphere soil (RS) and the rhizoplane/endorhizosphere (RE) was determined by PCR-denaturing gradient gel electrophoresis. Seed treatments consisted of consortia of two PGPR strains alone or combined with AMF or AMF alone. The PGPR strains were Pseudomonas spp. which included some or all of the following plant growth promoting properties: phosphate solubilisation and production of indole-3-acetic acid, siderophores, 1-aminocyclopropane-1-carboxylate deaminase and diacetyl-phloroglucinol. The mycorrhizal inoculum was an indigenous AMF consortium isolated from the field with the lowest level of fertilization and yield. Variation partitioning analysis of the DGGE data indicated a predominant effect of the wheat growth stage (30.4% of the variance, PZ0.001) over the type of field (9.0%, PZ0.027) on the bacterial community structure in the RE. The impact of plant age in the RS was less than in the RE and the bacterial community structure of the field with the highest input of fertilization was very different from the low input fields. The bio-inoculants induced a significant modification in the bacterial community structure. In the RS, the bacterial consortia explained 28.3% (PZ0.001) and the presence of AMF 10.6% (PZ0.02) of the variance and the same trend was observed in the RE. Plant yield or grain quality was either increased or remained unaffected. For example, protein content was significantly higher in the treated plants' grain compared to the control plants; maximum values were obtained when the PGPR were co-inoculated with the AMF. The percentage of root colonization by AMF was significantly higher in the treatments containing a mycorrhizal inoculum than in the untreated control and remained unaffected by the PGPR treatments. In conclusion, the wheat rhizobacterial community structure is highly dynamic and influenced by different factors such as the plant's age, the fertilizer input and the type of bio-inoculant. In addition, there is a distance-related effect of the root on the bacterial community. Finally, a combined bio-inoculation of diacetyl-phloroglucinol producing PGPR strains and AMF can synergistically improve the nutritional quality of the grain without negatively affecting mycorrhizal growth.

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“…In Pseudomonas chlororaphis PCL1391, the production of the antifungal metabolite phenazine-1-carboxamide (PCN) (Chin-A-Woeng et al, 2003) is synthesized through expression of the biosynthetic phzABCDEFGH operon (Chin-A-Woeng et al, 1998). Previous work led to a model of regulation of PCN production involving three different groups of genes: the phzI/ phzR quorum-sensing system (Chin-A-Woeng et al, 2001b), gacS/gacA (global antibiotic and cyanide control), and the regulatory psrA gene (Pseudomonas sigma regulator) (Chin-A-Woeng et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

et al. 2006

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Production of the secondary metabolite phenazine-1-carboxamide (PCN) by Pseudomonas chlororaphis PCL1391 is crucial for biocontrol activity against the phytopathogen Fusarium oxysporum f. sp. radicis lycopersici on tomato. Regulation of PCN production involves the two-component signalling system GacS/GacA, the quorum-sensing system PhzI/PhzR and the regulator PsrA. This paper reports that a functional rpoS is required for optimal PCN and N-hexanoyl-l-homoserine lactone (C6-HSL) production. Constitutive expression of rpoS is able to complement partially the defect of a psrA mutant for PCN and N-acylhomoserine lactone production. Western blotting shows that rpoS is regulated by gacS. Altogether, these results suggest the existence of a cascade consisting of gacS/gacA upstream of psrA and rpoS, which influence expression of phzI/phzR. Overproduction of phzR complements the effects on PCN and C6-HSL production of all mutations tested in the regulatory cascade, which shows that a functional quorum-sensing system is essential and sufficient for PCN synthesis. In addition, the relative amounts of PCN, phenazine-1-carboxylic acid and C6-HSL produced by rpoS and psrA mutants harbouring a constitutively expressed phzR indicate an even more complex network of interactions, probably involving other genes. Preliminary microarray analyses of the transcriptomics of the rpoS and psrA mutants support the model of regulation described in this study and allow identification of new genes that might be involved in secondary metabolism.

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Phenazines and their role in biocontrol by Pseudomonas bacteria

Cited by 319 publications

References 283 publications

Carbon source regulation of antibiotic production

Carbon source regulation of antibiotic production

Plant growth stage, fertiliser management and bio-inoculation of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria affect the rhizobacterial community structure in rain-fed wheat fields

Regulatory roles of psrA and rpoS in phenazine-1-carboxamide synthesis by Pseudomonas chlororaphis PCL1391

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