Selection for biocontrol bacteria antagonistic toward Rosellinia necatrix by enrichment of competitive avocado root tip colonizers

Pliego, Clara; Cazorla, Francisco M.; González-Sánchez, María Ángeles; Pérez‐Jiménez, R. M.; Vicente, Antonio de; Ramos, Cayo

doi:10.1016/j.resmic.2007.02.011

Cited by 35 publications

(42 citation statements)

References 30 publications

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“…Competitive colonization performance has been used as trait for the selection of better strains for biocontrol (30,39). Here we have shown that enhancing rhizosphere competitive colonization by manipulating traits known to be relevant for this process may result in an improvement in biocontrol of pathogenic fungi in the root.…”

Section: Vol 77 2011 Competitive Rhizosphere Colonization and Biocomentioning

confidence: 93%

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

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119

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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...

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Section: Vol 77 2011 Competitive Rhizosphere Colonization and Biocomentioning

confidence: 93%

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

Self Cite

119

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Section: Screening For Colonisationmentioning

confidence: 99%

“…Recently, a new strategy for screening bacterial BCAs was developed based in the efficient colonisation of the plant root to avoid selection by antagonism because future registration of antibiotic-producing strains could be more difficult (Kamilova et al 2005;Pliego et al 2007;Egamberdieva and Kucharova 2009). This technique is based on several cycles of inoculation and reisolation of microorganisms from the plant root tip (Kamilova et al 2005;Pliego et al 2007). By using this strategy, enhanced root colonisers were isolated, which supported the notion that these bacteria could act through the mechanism of competition for niches and nutrients (Pliego et al 2008); however, excellent colonisation is not sufficient by itself for excellent biocontrol because it would be also needed the ability to differentially colonize the root zones that could be the target of the pathogen (Kamilova et al 2005;Pliego et al 2008).…”

Section: Screening For Colonisationmentioning

confidence: 99%

“…Furthermore, despite the antifungal activities shown by most of these isolates on agar plates, some strains do not show biocontrol activity in the rhizosphere environment, probably due to poor colonisation and therefore poor delivery of antifungal metabolites along the root system. To gain insight in the colonising aspects and to improve the selection of potential BCAs, a novel procedure based on selection of competitive root tip colonisers (Kamilova et al 2005) was recently applied to generate a collection of bacterial isolates that efficiently colonise the roots of avocado plantlets (Pliego et al 2007). This strategy yielded rhizobacterial strains with efficient colonisation traits, especially the strain Pseudomonas pseudoalcaligenes AVO110, which is a non-antibiotic-producing strain that is antagonistic to R. necatrix, with biocontrol activity in the avocado/Rosellinia test system competition for niches and nutrients as its mode of action (Pliego et al 2008).…”

Section: Future Prospectsmentioning

confidence: 99%

“…However, these previous strategies did not take into account the influence of biotic and abiotic factors in the rhizosphere of Rosellinia-infected plants, and they introduced a bias, selecting mainly those strains with biocontrol activity based on the mechanism used in the selection method, such as production of antifungal compounds (Cazorla et al 2006 or root colonisation (Pliego et al 2007). For this reason, a direct plant-protection strategy was developed to screen for candidate BCAs that considered all potential biocontrol traits (red arrow in Fig.…”

Section: Future Prospectsmentioning

confidence: 99%

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Screening for candidate bacterial biocontrol agents against soilborne fungal plant pathogens

et al. 2010

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Over the years, many bacterial isolates have been evaluated as potential biocontrol agents against soilborne fungal phytopathogens. However, few of them were ultimately successful after evaluation in field trials. One of the major reasons for this failure is the lack of appropriate screening procedures to select the most suitable microorganisms for disease control in diverse soil environments. For this reason, the study of bacterial screening has a future that is characterised by many technical and conceptual challenges. In this review, we summarise and discuss the convenience of use of the main screening methods currently applied to select bacterial candidates for biocontrol of fungal and oomycete soilborne phytopathogens. Also, a comparative case study of the application of different screening methods applied to an experimental pathosystem is shown, revealing the success of bacterial candidates selected by different strategies for biocontrol of the phytopathogenic fungus Rosellinia necatrix in avocado plants. Screening for antagonism against this fungal pathogen, one of the more straightforward methods used for the selection of bacterial biocontrol agents, was proven to be a valid strategy for this experimental system.

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Microbial Control of Plant Root Diseases

Lugtenberg

Malfanova

Kamilova

et al. 2013

Molecular Microbial Ecology of the Rhizosphere

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Selection for biocontrol bacteria antagonistic toward Rosellinia necatrix by enrichment of competitive avocado root tip colonizers

Cited by 35 publications

References 30 publications

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

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

Screening for candidate bacterial biocontrol agents against soilborne fungal plant pathogens

Microbial Control of Plant Root Diseases

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