Root Colonization by Phenazine-1-Carboxamide-Producing Bacterium <i>Pseudomonas chlororaphis</i> PCL1391 Is Essential for Biocontrol of Tomato Foot and Root Rot

Chin-A-Woeng, Thomas F. C.; Bloemberg, Guido V.; Mulders, Ine H. M.; Dekkers, Linda C.; Lugtenberg, Ben

doi:10.1094/mpmi.2000.13.12.1340

Cited by 293 publications

(121 citation statements)

References 22 publications

Supporting

Mentioning

118

Contrasting

Unclassified

Order By: Relevance

“…Since efficient rhizosphere colonization is a requirement for biotechnological applications in biocontrol and rhizoremediation (8,20), engineering of competitiveness can be rendered in more effective strains. It has been previously shown that after three enrichment cycles in the rhizosphere, a P. fluorescens strain harboring a mutation in the mutY gene showed enhanced competitive colonization (12).…”

Section: Discussionmentioning

confidence: 99%

Rhizosphere Selection of Highly Motile Phenotypic Variants of Pseudomonas fluorescens with Enhanced Competitive Colonization Ability

Martínez‐Granero

Rivilla

Martín

2006

Appl Environ Microbiol

View full text Add to dashboard Cite

Phenotypic variants of Pseudomonas fluorescens F113 showing a translucent and diffuse colony morphologyshow enhanced colonization of the alfalfa rhizosphere. We have previously shown that in the biocontrol agent P. fluorescens F113, phenotypic variation is mediated by the activity of two site-specific recombinases, Sss and XerD. By overexpressing the genes encoding either of the recombinases, we have now generated a large number of variants (mutants) after selection either by prolonged laboratory cultivation or by rhizosphere passage. All the isolated variants were more motile than the wild-type strain and appear to contain mutations in the gacA and/or gacS gene. By disrupting these genes and complementation analysis, we have observed that the Gac system regulates swimming motility by a repression pathway. Variants isolated after selection by prolonged cultivation formed a single population with a swimming motility that was equal to the motility of gac mutants, being 150% more motile than the wild type. The motility phenotype of these variants was complemented by the cloned gac genes. Variants isolated after rhizosphere selection belonged to two different populations: one identical to the population isolated after prolonged cultivation and the other comprising variants that besides a gac mutation harbored additional mutations conferring higher motility. Our results show that gac mutations are selected both in the stationary phase and during rhizosphere colonization. The enhanced motility phenotype is in turn selected during rhizosphere colonization. Several of these highly motile variants were more competitive than the wild-type strain, displacing it from the root tip within 2 weeks.Pseudomonas fluorescens F113 is a biocontrol agent isolated from the sugar beet rhizosphere (11) and capable of protecting this crop against the pathogenic fungus Pythium ultimum (17,31). In addition, derivatives of this strain with the ability to degrade polychlorinated biphenyls have been constructed by the integration of the Burkholderia sp. strain LB400 bph operon under the control of different regulatory elements (4, 38). P. fluorescens F113 is a good rhizosphere colonizer and can colonize the rhizospheres of different plants such as alfalfa (37), tomato (33), and pea (23).During alfalfa rhizosphere colonization, F113 undergoes phenotypic variation (27) characterized by the appearance of variants with a translucent and diffuse colony morphology. These variants were more prevalent in distal parts of the root (1, 27). Phenotypic variation in this strain appears to be mediated by the activity of two site-specific recombinases, Sss and XerD, since mutants with mutations in either of the genes encoding these recombinases show a severe reduction in the appearance of phenotypic variants after rhizosphere colonization and prolonged laboratory cultivation (22). Phenotypic variation seems to be an important trait for rhizosphere colonization, and mutants of different Pseudomonas strains affected in the sss (10, 22) or xerD (22) genes are ...

show abstract

Section: Discussionmentioning

confidence: 99%

Rhizosphere Selection of Highly Motile Phenotypic Variants of Pseudomonas fluorescens with Enhanced Competitive Colonization Ability

Martínez‐Granero

Rivilla

Martín

2006

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…It has been previously shown that efficient colonization is a prerequisite for efficient biocontrol, since mutant derivatives of the phenazine-1-carboxamide-producing bacterium Pseudomonas chlororaphis PCL1391, impaired in competitive colonization, completely lost biocontrol ability against F. oxysporum f. sp. radicis-lycopersici in tomato plants (10). It was therefore possible, that a hypercompetitive strain could perform better than the wild-type strain for fungal biocontrol in the root.…”

Section: Vol 77 2011 Competitive Rhizosphere Colonization and Biocomentioning

confidence: 99%

Pseudomonas fluorescens F113 Mutant with Enhanced Competitive Colonization Ability and Improved Biocontrol Activity against Fungal Root Pathogens

Barahona

Navazo

Martínez‐Granero

et al. 2011

Appl Environ Microbiol

115

View full text Add to dashboard Cite

Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible.Pseudomonas fluorescens F113rif (F113) is a biocontrol agent isolated from the sugar beet rhizosphere (36) that is able to suppress take-all disease produced by the oomycete Pythium ultimum (18). This strain, which is able to efficiently colonize the rhizosphere of a variety of plants (12,14,27,33), is being used as a model for rhizosphere colonization (3,26,33) and has also been genetically modified for polychlorinated biphenyl (PCB) rhizoremediation (5, 13, 41). The biocontrol ability of this strain has been related to the production of a series of secondary metabolites, including siderophores, diacetyl-phloroglucinol (DAPG), hydrogen cyanide, and an extracellular protease (1, 36), whose production is regulated by the GacAS posttranscriptional system (1).The GacAS system, as well as SadB and the Wsp system, independently regulates swimming motility in strain F113 (29). In this strain mutants affected in sadB and wspR showed increased swimming motility. In F113, the sadB and wspR genes showed 84% and 83% identities with their Pseudomonas aeruginosa orthologues and are highly conserved in sequence and genomic context with orthologues in all the sequenced P. fluorescens strains. SadB and WspR possibly repress swimming mot...

show abstract

“…Beneficial plant-microbial interactions in the rhizosphere can result in the promotion of plant health and development. Aggressive colonization and an ability to compete with resident microorganisms predisposes certain soilborne Pseudomonas strains to the establishment of such beneficial interactions (2,3). Colonization is a multigenic process under the influence of many environmental factors.…”

mentioning

confidence: 99%

Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions

Mark

Dow

Kiely

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

220

166

View full text Add to dashboard Cite

Molecules exuded by plant roots are thought to act as signals to influence the ability of microbial strains to colonize the roots and to survive in the rhizosphere. Differential bacterial responses to signals from different plant species may mediate the selection of specific rhizosphere populations. Very little, however, is known about the effects of plant exudates on patterns of bacterial gene expression. Here, we have tested the concept that plant root exudates modulate expression of bacterial genes involved in establishing microbe-plant interactions. We have examined the influence on the Pseudomonas aeruginosa PA01 transcriptome of exudates from two varieties of sugarbeet that select for genetically distinct pseudomonad populations in the rhizosphere. The response to the two exudates showed only a partial overlap; the majority of those genes with altered expression was regulated in response to only one of the two exudates. Genes with altered expression included those with functions previously implicated in microbe-plant interactions, such as aspects of metabolism, chemotaxis and type III secretion, and a subset with putative or unknown function. Use of a panel of mutants with targeted disruptions allowed us to identify previously uncharacterized genes with roles in the competitive ability of P. aeruginosa in the rhizosphere within this subset. No genes with host-specific effects were identified. Homologues of the genes identified occur in the genomes of both beneficial and pathogenic root-associated bacteria, suggesting that this strategy may help to elucidate molecular interactions that are important for biocontrol, plant growth promotion, and plant pathogenesis.Pseudomonas ͉ Rhizosphere colonization

show abstract

Root Colonization by Phenazine-1-Carboxamide-Producing Bacterium Pseudomonas chlororaphis PCL1391 Is Essential for Biocontrol of Tomato Foot and Root Rot

Cited by 293 publications

References 22 publications

Rhizosphere Selection of Highly Motile Phenotypic Variants of Pseudomonas fluorescens with Enhanced Competitive Colonization Ability

Rhizosphere Selection of Highly Motile Phenotypic Variants of Pseudomonas fluorescens with Enhanced Competitive Colonization Ability

Pseudomonas fluorescens F113 Mutant with Enhanced Competitive Colonization Ability and Improved Biocontrol Activity against Fungal Root Pathogens

Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions

Contact Info

Product

Resources

About