Quorum-sensing system influences root colonization and biological control ability in Pseudomonas fluorescens 2P24

Wei, Hengling; Zhang, Liqun

doi:10.1007/s10482-005-9028-8

Cited by 137 publications

(96 citation statements)

References 51 publications

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“…We therefore thoroughly tested root colonization of the different strains and showed that this trait is under positive QS regulation in P. aeruginosa PUPa3. This is similar to the results found for P. fluorescens 2P24, in which the QS mutant also showed a reduced capability for root colonization (60). Another report showing positive QS regulation of root colonization was for PGPR Pseudomonas chlororaphis strain 30-84; for this species it was suggested that production of phenazines, which are antibiotics produced by this strain, is under QS regulation.…”

Section: Discussionsupporting

confidence: 85%

LasI/R and RhlI/R Quorum Sensing in a Strain ofPseudomonas aeruginosaBeneficial to Plants

Steindler

Bertani

Sordi

et al. 2009

Appl Environ Microbiol

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Pseudomonas aeruginosa possesses three quorum-sensing (QS) systems which are key in the expression of a large number of genes, including many virulence factors. Most studies of QS in P. aeruginosa have been performed in clinical isolates and have therefore focused on its role in pathogenicity. P. aeruginosa, however, is regarded as a ubiquitous organism capable of colonizing many different environments and also of establishing beneficial associations with plants. In this study we examined the role of the two N-acyl homoserine lactone systems known as RhlI/R and LasI/R in the environmental rice rhizosphere isolate P. aeruginosa PUPa3. Both the Rhl and Las systems are involved in the regulation of plant growth-promoting traits. The environmental P. aeruginosa PUPa3 is pathogenic in two nonmammalian infection models, and only the double las rhl mutants are attenuated for virulence. In fact it was established that the two QS systems are not hierarchically organized and that they are both important for the colonization of the rice rhizosphere. This is an in-depth genetic and molecular study of QS in an environmental P. aeruginosa strain and highlights several differences with QS regulation in the clinical isolate PAO1.Pseudomonas aeruginosa has been intensively studied by the scientific community because it is an opportunistic pathogen able to chronically colonize and infect cystic fibrosis patients (30). An important aspect of this bacterium is its capability to adapt to the host environment through the extensive and complex transcriptional regulation of an arsenal of virulence genes. A key player in this response is the quorum-sensing (QS) cell-cell communication system, which coordinates the behavior of P. aeruginosa communities. In fact, the transcriptional regulation of many virulence genes is controlled by two N-acyl homoserine lactone (AHL)-dependent QS systems called LasI/R and RhlI/R (16, 48).In the LasI/R system, lasI directs the synthesis of N-(3-oxododecanoyl)-homoserine lactone (3-oxo-C12-HSL), which binds and activates the cognate response regulator LasR, resulting in the regulation of target gene expression. In the RhlI/R system, on the other hand, rhlI directs the synthesis of N-(butanoyl)-homoserine lactone (C4-HSL), which then interacts with the cognate RhlR, influencing transcription of target genes. These two QS systems are probably among the most studied in bacteria, and their regulons are fundamental to the pathogenicity of P. aeruginosa (48). Importantly, the two systems are intimately connected, being hierarchically organized with the LasI/R system regulating the transcription of rhlI-rhlR (29). The two QS regulons overlap, and together they constitute approximately 10% of the genes in P. aeruginosa, including factors like elastase, alkaline protease, exotoxin A, rhamnolipids, and pyocyanin, as well as being important for the regulation of biofilm formation (19,46,58). The two systems are themselves controlled by different regulators, allowing QS to respond and be modulated also by an array of...

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Section: Discussionsupporting

confidence: 85%

LasI/R and RhlI/R Quorum Sensing in a Strain ofPseudomonas aeruginosaBeneficial to Plants

Steindler

Bertani

Sordi

et al. 2009

Appl Environ Microbiol

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“…If generalist anti-B. dendrobatidis bacteria, such as pseudomonads, are important as an amphibian defense mechanism against B. dendrobatidis, then the abundance of these bacterial species may be a key factor in protection (54,55). In some cases, high cell density is needed to produce inhibitory metabolites because the metabolites are produced in high quantities only when bacteria form a biofilm and undergo quorum sensing (56,57).…”

Section: Discussionmentioning

confidence: 99%

Antifungal Bacteria on Woodland Salamander Skin Exhibit High Taxonomic Diversity and Geographic Variability

Muletz‐Wolz

DiRenzo

Yarwood³

et al. 2017

Appl Environ Microbiol

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Diverse bacteria inhabit amphibian skin; some of those bacteria inhibit growth of the fungal pathogen Batrachochytrium dendrobatidis. Yet there has been no systematic survey of anti-B. dendrobatidis bacteria across localities, species, and elevations. This is important given geographic and taxonomic variations in amphibian susceptibility to B. dendrobatidis. Our collection sites were at locations within the Appalachian Mountains where previous sampling had indicated low B. dendrobatidis prevalence. We determined the numbers and identities of anti-B. dendrobatidis bacteria on 61 Plethodon salamanders (37 P. cinereus, 15 P. glutinosus, 9 P. cylindraceus) via culturing methods and 16S rRNA gene sequencing. We sampled co-occurring species at three localities and sampled P. cinereus along an elevational gradient (700 to 1,000 meters above sea level [masl]) at one locality. We identified 50 anti-B. dendrobatidis bacterial operational taxonomic units (OTUs) and found that the degree of B. dendrobatidis inhibition was not correlated with relatedness. Five anti-B. dendrobatidis bacterial strains occurred on multiple amphibian species at multiple localities, but none were shared among all species and localities. The prevalence of anti-B. dendrobatidis bacteria was higher at Shenandoah National Park (NP), VA, with 96% (25/26) of salamanders hosting at least one anti-B. dendrobatidis bacterial species compared to 50% (7/14) at Catoctin Mountain Park (MP), MD, and 38% (8/21) at Mt. Rogers National Recreation Area (NRA), VA. At the individual level, salamanders at Shenandoah NP had more anti-B. dendrobatidis bacteria per individual ( ϭ 3.3) than those at Catoctin MP ( ϭ 0.8) and at Mt. Rogers NRA ( ϭ 0.4). All salamanders tested negative for B. dendrobatidis. Anti-B. dendrobatidis bacterial species are diverse in central Appalachian Plethodon salamanders, and their distribution varied geographically. The antifungal bacterial species that we identified may play a protective role for these salamanders.IMPORTANCE Amphibians harbor skin bacteria that can kill an amphibian fungal pathogen, Batrachochytrium dendrobatidis. Some amphibians die from B. dendrobatidis infection, whereas others do not. The bacteria that can kill B. dendrobatidis, called anti-B. dendrobatidis bacteria, are thought to influence the B. dendrobatidis infection outcome for the amphibian. Yet how anti-B. dendrobatidis bacterial species vary among amphibian species and populations is unknown. We determined the distribution of anti-B. dendrobatidis bacterial species among three salamander species (n ϭ 61) sampled at three localities. We identified 50 unique anti-B. dendrobatidis bacterial species and found that all of the tested salamanders were negative for B. dendrobatidis. Five anti-B. dendrobatidis bacterial species were commonly detected, suggesting a stable, functional association with these salamanders. The number of

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“…Among them, 2,4-DAPG is a well-characterized compound due to its broad spectrum of activity and in situ inhibitory action on phytopathogens (Bangera & Thomashow, 1999). It functions as a major ingredient in biocontrol agents, such as Pseudomonas fluorescens strains Q2-87, F113, CHA0 and 2P24, used to protect crops against a number of plant diseases such as wheat take-all caused by Gaeumannomyces graminis, sugar beet seedlings dampingoff caused by Pythium ultimum, tobacco black root rot caused by Thielaviopsis basicola, cotton rhizoctoniosis caused by Rhizoctonia solani and tomato bacterial wilt caused by Ralstonia solanacearum (Bangera & Thomashow, 1999;Fenton et al, 1992;Schnider-Keel et al, 2000;Zhou et al, 2005;Wei & Zhang, 2006).…”

Section: Introductionmentioning

confidence: 99%

The resistance-nodulation-division efflux pump EmhABC influences the production of 2,4-diacetylphloroglucinol in Pseudomonas fluorescens 2P24

Tian

Duan

et al. 2010

Microbiology

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The polyketide metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) plays a major role in the biological control of soil-borne plant diseases by Pseudomonas fluorescens 2P24. Two mutants (PM810 and PM820) with increased extracellular accumulation of 2,4-DAPG were isolated using transposon mutagenesis. The disrupted genes in these two mutants shared .80 % identity with the genes of the EmhR-EmhABC resistance-nodulation-division (RND) efflux system of P. fluorescens cLP6a. The deletion of emhA (PM802), emhB (PM803) or emhC (PM804) genes in strain 2P24 increased the extracellular accumulation of 2,4-DAPG, whereas the deletion of the emhR (PM801) gene decreased the biosynthesis of 2,4-DAPG. The promoter assay confirmed the elevated transcription of emhABC in the EmhR disrupted strain (PM801) and an indirect negative regulation of 2,4-DAPG biosynthetic locus transcription by the EmhABC efflux pump. Induction by exogenous 2,4-DAPG led to remarkable differences in transcription of chromosomeborne phlA : : lacZ fusion in PM901 and PM811 (emhA " ) strains. Additionally, the EmhABC system in strain 2P24 was involved in the resistance to a group of toxic compounds, including ampicillin, chloramphenicol, tetracycline, ethidium bromide and crystal violet. In conclusion, our results suggest that the EmhABC system is an important element that influences the production of antibiotic 2,4-DAPG and enhances resistance to toxic compounds in P. fluorescens 2P24.

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Quorum-sensing system influences root colonization and biological control ability in Pseudomonas fluorescens 2P24

Cited by 137 publications

References 51 publications

LasI/R and RhlI/R Quorum Sensing in a Strain ofPseudomonas aeruginosaBeneficial to Plants

LasI/R and RhlI/R Quorum Sensing in a Strain ofPseudomonas aeruginosaBeneficial to Plants

Antifungal Bacteria on Woodland Salamander Skin Exhibit High Taxonomic Diversity and Geographic Variability

The resistance-nodulation-division efflux pump EmhABC influences the production of 2,4-diacetylphloroglucinol in Pseudomonas fluorescens 2P24

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