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Insecticidal activity in root-colonizing plant-beneficial pseudomonads: Molecular mechanisms and exploitation for pest control

Applicant Keel Christoph
Number 138248
Funding scheme Project funding
Research institution Département de Microbiologie Fondamentale Faculté de Biologie et de Médecine Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Experimental Microbiology
Start/End 01.01.2012 - 30.04.2015
Approved amount 491'000.00
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Keywords (9)

Pseudomonas; plant-beneficial; toxin; insecticidal; biological pest control; rhizosphere; molecular host-microbe interactions; insects; autofluorescent reporters

Lay Summary (English)

Lead
Lay summary

Insect pests and fungal diseases cause major damage to agricultural crops and in particular those affecting below-ground plant parts are very difficult to ward off with chemical pesticides. Plant protection with beneficial soil bacteria is an ecologically sound alternative. We study biocontrol strains of Pseudomonas fluorescens that colonize roots and suppress fungal plant diseases. We discovered that phylogenetically defined groups of these pseudomonads exhibit not only antifungal, but also potent oral and systemic insecticidal activity towards different lepidopteran pests. We identified a locus encoding a novel insect toxin we termed Fit for P. fluorescens insecticidal toxin. We demonstrated that the Fit toxin contributes substantially to insecticidal activity.

In a first part of the present project, we aim at unravelling regulatory mechanisms that control Fit insect toxin expression, activity and transport during interaction of P. fluorescens with the insect host. A particular focus will be on Fit locus-specific regulators and their interconnection with global regulatory and signalling systems in the bacteria. The approach will include an activity mapping of the Fit toxin to identify domains that are indispensable for insect toxicity and toxin transport by the Fit locus-encoded protein secretion system. In addition, we will try to identify further traits contributing to anti-insect activity using a genomic expression library approach.

In a second part, we will investigate two possibilities of exploiting the Fit toxin as a novel means for pest control, i.e. by treating plant surfaces with Fit producing pseudomonads and by controlled expression of the Fit toxin or active fragments thereof directly in the plant. The efficacy of the two methods in controlling important root and leaf pests will then be tested in plant assays.

We expect that our discovery of potent oral anti-insect activity in plant-beneficial pseudomonads will open new possibilities for combined microbial pest and disease control, since these bacteria are very efficient, vector-independent below-ground plant parts colonizers. In a longer term perspective, the expression of the Fit toxin or active fragments in the plant may open up the possibility to develop new transgenic crops resistant to insect pests, offering an alternative to Bt crops.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Domain shuffling in a sensor protein contributed to the evolution of insect pathogenicity in plant-beneficial Pseudomonas protegens.
Kupferschmied Peter, Péchy-Tarr Maria, Imperiali Nicola, Maurhofer Monika, Keel Christoph (2014), Domain shuffling in a sensor protein contributed to the evolution of insect pathogenicity in plant-beneficial Pseudomonas protegens., in PLoS Pathogens, 10(2), e1003964.
Full-genome sequence of the plant growth-promoting bacterium Pseudomonas protegens CHA0.
Jousset Alexandre, Schuldes Joerg, Keel Christoph, Maurhofer Monika, Daniel Rolf, Scheu Stefan, Thuermer Andrea (2014), Full-genome sequence of the plant growth-promoting bacterium Pseudomonas protegens CHA0., in Genome Announcements, 2(2), e00322.
Insecticidal activity of plant root-associated bacteria.
Kupferschmied Peter, Keel Christoph (2014), Insecticidal activity of plant root-associated bacteria., in Bertrand Cédric (ed.), Presses Universitaires de Perpignan., Perpignan, France., 52-58.
Control and host-dependent activation of insect toxin expression in a root-associated biocontrol pseudomonad.
Péchy-Tarr Maria, Borel Naomi, Kupferschmied Peter, Turner Vincent, Binggeli Olivier, Radovanovic Dragica, Maurhofer Monika, Keel Christoph (2013), Control and host-dependent activation of insect toxin expression in a root-associated biocontrol pseudomonad., in Environmental Microbiology, 15(3), 736-750.
Oral insecticidal activity of plant-associated pseudomonads.
Ruffner Beat, Péchy-Tarr Maria, Ryffel Florian, Hoegger Patrik, Obrist Christian, Rindlisbacher Alfred, Keel Christoph, Maurhofer Monika (2013), Oral insecticidal activity of plant-associated pseudomonads., in Environmental Microbiology, 15(3), 751-763.
Promise for plant pest control: root-associated pseudomonads with insecticidal activities.
Kupferschmied Peter, Maurhofer Monika, Keel Christoph (2013), Promise for plant pest control: root-associated pseudomonads with insecticidal activities., in Frontiers in Plant Science, 4, 287.
Evolutionary patchwork of an insecticidal toxin shared between plant-associated pseudomonads and the insect pathogens Photorhabdus and Xenorhabdus
Ruffner Beat, Péchy-Tarr Maria, Höfte Monica, Bloemberg Guido, Grunder Jürg, Keel Christoph, Maurhofer Monika, Evolutionary patchwork of an insecticidal toxin shared between plant-associated pseudomonads and the insect pathogens Photorhabdus and Xenorhabdus, in BMC Genomics.

Collaboration

Group / person Country
Types of collaboration
Joyce Loper, USDA-ARS and Oregon State University, Corvallis, OR United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
Jos Raaijmakers, Department of Microbial Ecology, NIOO-KNAW, Wageningen Netherlands (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Consuela de Moraes, Institute for Agricultural Sciences, Biocommunication & Entomology, ETH Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Dimitri Mavrodi, Department of Biological Sciences, University of Southern Mississipi, Hattiesburg United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Alexandre Jousset, Ecology and Biodiversity, Utrecht University Netherlands (Europe)
- Publication
Jürg Grunder, Natural Resources Sciences, Phytomedicine, ZAHW Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Guido Bloemberg, Institut für Medizinische Mikrobiologie, University of Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Ted Turlings, Fundamental & Applied Research in Chemical Ecology, University of Neuchatel Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Yvan Moënne-Loccoz, Claire Prigent-Combaret, Ecologie Microbienne, Université de Lyon 1, Lyon France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Brion Duffy, Natural Ressources Sciences, Environmental Genomics and Systems Biology, ZAHW Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Philippe Reymond, Department of Plant Molecular Biology, University of Lausanne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Fabio Mascher, Raphael Charles, Agroscope location Changins Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Monica Höfte, Laboratory of Phytopathology, Ghent University Belgium (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Patrik Hoegger, Philippe Camblin, Syngenta Crop Protection AG, Stein Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Regina Kleespies, Johannes Jehle, Institute for Biological Control, Julius Kühn-Institut, Darmstadt Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Michael Bonkowski, Terrestrial Ecology, University of Cologne, Germany Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Liga Jankevica, Laboratory of Experimental Entomology and Microbiology, University of Latvia, Riga Latvia (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Rhizosphere 4 International Conference Talk given at a conference Convenor talk: A sensor protein controlling host-specific expression of an insect pathogenicity factor in plant-beneficial rhizosphere pseudomonads 21.06.2015 Maastricht, Netherlands Keel Christoph;
10th International PGPR Workshop Talk given at a conference Keynote presentation: Plant-beneficial rhizosphere bacteria with insecticidal activities – Molecular basis of virulence 16.06.2015 Liège, Belgium Keel Christoph;
10th International PGPR Workshop Talk given at a conference What are the features that plant-beneficial pseudomonads require to become insect pathogens? (presented by Pascale Flury)) 16.06.2015 Liège, Belgium Flury Pascale; Péchy-Tarr Maria; Maurhofer Monika; Keel Christoph;
10th International PGPR Workshop Poster Investigating the role of Pseudomonas protegens extracellular polysaccharides in host colonization and pathogenicity (presented by Céline Terrettaz). 16.06.2015 Liège, Belgium Keel Christoph; Maurhofer Monika; Péchy-Tarr Maria;
10th International PGPR Workshop Talk given at a conference Keynote presentation: Plant-beneficial rhizosphere bacteria with insecticidal activities – Spectrum and stages of infection 16.06.2015 Liège, Belgium Maurhofer Monika;
10th International PGPR Workshop Talk given at a conference The sweetest trick: O-polysaccharides protect plant-beneficial Pseudomonads against antimicrobial peptides during insect infection (presented by Peter Kupfreschmied). 16.06.2015 Liège, Belgium Flury Pascale; Maurhofer Monika; Péchy-Tarr Maria; Keel Christoph;
15th Meeting of the IOBC-WPRS WG Microbial and Nematode Control of Invertebrate Pests Talk given at a conference What are the features that plant-beneficial pseudomonads require to become insect pathogens? (presented by Pascale Flury) 07.06.2015 Riga, Latvia Flury Pascale; Péchy-Tarr Maria; Keel Christoph; Maurhofer Monika;
15th Meeting of the IOBC-WPRS WG Microbial and Nematode Control of Invertebrate Pests Talk given at a conference Keynote presentation: The secret life of Pseudomonas protegens CHA0: A switch from antifungal agent to insect killer. 07.06.2015 Riga, Latvia Maurhofer Monika;
73rd Annual Meeting and Assembly of the Swiss Society for Microbiology Poster Investigating the role of Pseudomonas protegens extracellular polysaccharides in host colonization and pathogenicity (presented by Céline Terrettaz). 28.05.2015 Lugano, Switzerland Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika;
Seminar at the Department of Fundamental Microbiology Individual talk Live and let die: how do plant-beneficial pseudomonads infect and kill insects? (presented by P. Kupferschmied) 17.04.2015 Lausanne, Switzerland Keel Christoph;
73rd Annual Meeting and Assembly of the Swiss Society for Microbiology Talk given at a conference The sweetest trick: O-polysaccharides protect plant-beneficial Pseudomonads against antimicrobial peptides during insect infection (presente by Peter Kupferschmied). 28.03.2015 Lugano, Switzerland Maurhofer Monika; Keel Christoph; Flury Pascale;
Plant Pathology Seminaries at ETH Zurich Individual talk Battlefield rhizosphere: how root-colonizing pseudomonads interact with plants, plant pathogens, predators and insects. 13.10.2014 Zurich, Switzerland Maurhofer Monika;
59. Deutsche Pflanzenschutztagung Talk given at a conference Insektizide Aktivität in Wurzel-kolonisierenden Pseudomonas Bakterien (presented by Pascale Flury). 23.09.2014 Freiburg, Germany Keel Christoph; Maurhofer Monika; Flury Pascale;
2014 International Congress on Invertebrate Pathology and Microbial Control and 47th Annual Meeting of the Society for Invertebrate Pathology Poster Interplay of regulators controlling Fit insect toxin expression in the biocontrol bacterium Pseudomonas protegens (presented by Nicolas Imperiali). 03.08.2014 Mainz, Germany Maurhofer Monika; Péchy-Tarr Maria; Keel Christoph;
2014 International Congress on Invertebrate Pathology and Microbial Control and 47th Annual Meeting of the Society for Invertebrate Pathology Talk given at a conference Untangling insect pathogenicity in plant-beneficial pseudomonads by a combination of comparative genomics, bioassays and histopathology (presented by Pascale Flury). 03.08.2014 Mainz, Germany Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika; Flury Pascale;
2014 International Congress on Invertebrate Pathology and Microbial Control and 47th Annual Meeting of the Society for Invertebrate Pathology Poster Unbalanced polyphosphate levels impair insect pathogenicity of plant-beneficial Pseudomonas protegens. 03.08.2014 Mainz, Germany Maurhofer Monika; Péchy-Tarr Maria; Keel Christoph;
2014 International Congress on Invertebrate Pathology and Microbial Control and 47th Annual Meeting of the Society for Invertebrate Pathology Talk given at a conference Evolution of a sensor protein controlling production of an insecticidal toxin in plant-beneficial Pseudomonas protegens (Presented by Peter Kupferschmied). 03.08.2014 Mainz, Germany Keel Christoph; Maurhofer Monika; Péchy-Tarr Maria;
Seminaries in Plant Pathology at ETH Zurich Individual talk Insecticidal activity in root-colonizing plant-beneficial pseudomonads: molecular mechanisms and exploitation for pest control. 30.06.2014 Zurich, Switzerland Flury Pascale;
Seminars in Microbiology at ETH Science City Individual talk Plant-beneficial rhizosphere bacteria with insecticidal activities. 16.04.2014 Zurich, Switzerland Keel Christoph;
Agroscope Seminary Individual talk Battlefield rhizosphere: how root-colonizing pseudomonads interact with plants, plant pathogens, predators and insects. 15.01.2014 Zurich-Reckenholz, Switzerland Maurhofer Monika;
Seminaries of the Julius Kühn Institute Individual talk The secret life of plant-beneficial pseudomonads: from roots to insect guts. 09.01.2014 Darmstadt, Germany Maurhofer Monika;
Plant Pathology Seminaries at ETH Zurich Individual talk Insecticidal activity in root-colonizing plant-beneficial pseudomonads: molecular mechanisms and exploitation for pest control. 30.10.2013 Zurich, Switzerland Flury Pascale;
Seminary at the University of Daugavpils Individual talk Battlefield rhizosphere: how root-colonizing pseudomonads interact with plants, plant pathogens, predators and insects. 11.10.2013 Daugavpils, Latvia Maurhofer Monika;
Seminary at the University of Latvia Individual talk Battlefield rhizosphere: how root-colonizing pseudomonads interact with plants, plant pathogens, predators and insects. 09.10.2013 Riga, Latvia Maurhofer Monika;
Autumn Meeting of the Swiss Society of Phytiatry 2013 Poster Wurzelassoziierte Pseudomonaden mit toxischer Aktivität gegenüber Insekten (presented by Peter Kupferschmied). 26.09.2013 Changins-Nyon, Switzerland Maurhofer Monika; Keel Christoph; Péchy-Tarr Maria;
Autumn Meeting of the Swiss Society of Phytiatry 2013 Poster Untangling insect pathogenicity in plant-associated pseudomonads by a combination of comparative genomics and bioassays. 26.09.2013 Changins-Nyon, Switzerland Maurhofer Monika; Péchy-Tarr Maria; Flury Pascale; Keel Christoph;
Meeting of the Swiss Society of Phytiatry Talk given at a conference When Pseudomonas fluorescens CHA0 launches its insect toxin production (presented by Peter Kupferschmied). 13.09.2013 Frutigen, Switzerland Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika;
14th International Conference on Pseudomonas 2013 Poster Host-dependent activation of insecticidal toxin production in root-associated Pseudomonas protegens. 07.09.2013 Lausanne, Switzerland Péchy-Tarr Maria; Keel Christoph; Maurhofer Monika;
14th International Conference on Pseudomonas 2013 Poster Evolution of a sensor protein: domain shuffling for tight control of toxin expression in Pseudomonas protegens (presented by P. Kupferschmied). 07.09.2013 Lausanne, Switzerland Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika;
14th International Conference on Pseudomonas 2013 Talk given at a conference Keynote presentation: Plant-beneficial pseudomonads as pathogens for insects. 07.09.2013 Lausanne, Switzerland Keel Christoph;
14th International Conference on Pseudomonas 2013 Poster Untangling insect pathogenicity in plant-associated pseudomonads by a combination of comparative genomics and bioassays. 07.09.2013 Lausanne, Switzerland Keel Christoph; Maurhofer Monika; Péchy-Tarr Maria; Flury Pascale;
10th International Congress of Plant Pathology Talk given at a conference Insect toxin producing plant-associated pseudomonads: Can they be used for joint biocontrol of plant diseases and insect pests? (presented by Monika Maurhofer) 25.08.2013 Beijing, China Péchy-Tarr Maria; Flury Pascale; Maurhofer Monika; Keel Christoph;
14th Meeting of the IOBC/WPRS WG Insect Pathogens and Entomoparasitic Nematodes Talk given at a conference Untangling insect pathogenicity in plant-beneficial pseudomonads by a combination of comparative genomics and bioassays (presented by Pascale Flury). 16.06.2013 Zagreb, Croatia Péchy-Tarr Maria; Flury Pascale; Keel Christoph; Maurhofer Monika;
14th Meeting of the IOBC/WPRS WG Insect Pathogens and Entomoparasitic Nematodes Talk given at a conference Do plant-associated insect toxin producing pseudomonads have the potential for the biocontrol of insect pests? (presented by Monika Maurhofer)) 16.06.2013 Zagreb, Croatia Péchy-Tarr Maria; Keel Christoph; Maurhofer Monika; Flury Pascale;
Seminaries of the Department of Fundamental Microbiology Individual talk Evolution is cleverer than you are: the story of the sensor protein FitF (presented by Peter Kupferschmied). 12.04.2013 Lausanne, Switzerland Keel Christoph;
5th Swiss Microbial Ecology (SME) Meeting Poster How can plant-associated pseudomonads with antifungal activity become insect pathogens? 04.02.2013 Murten, Switzerland Flury Pascale; Maurhofer Monika; Keel Christoph; Péchy-Tarr Maria;
Seminary on „Mikroorganismen für eine öko-effiziente Pflanzenernährung“, Institute of Plant Sciences, ETH Zurich Individual talk Den Pflanzen dienende Aktivitäten von Wurzel kolonisierenden Pseudomonaden. 10.01.2013 Zurich, Switzerland Maurhofer Monika;
Seminary at the University of Lyon Individual talk More than just disease suppression: skills of a rhizosphere pseudomonad. 14.12.2012 Lyon, France Maurhofer Monika;
IMUL-DMF Joint Seminar at CHUV Lausanne Individual talk Why start from scratch? The role and evolution of an insect toxin regulating sensor protein (presented by Peter Kupferschmied). 05.10.2012 Lausanne, Switzerland Keel Christoph;
Annual MPS PhD retreat Individual talk Cross talk in the rhizosphere: how plant-beneficial bacteria interact with plants, plant pathogens and insects. 27.09.2012 Avenches, Switzerland Maurhofer Monika;
Natural Products and Biocontrol 2012 Talk given at a conference Insecticidal activity of plant root-associated bacteria: host-specific expression of the Fit insect toxin (presented by Peter Kupferschmied). 19.09.2012 Perpignan, France Maurhofer Monika; Péchy-Tarr Maria; Keel Christoph;
Swiss Molecular Microbiology Meeting (SWIMM) 2012 on Microbial Survival Strategies Talk given at a conference Fancy microscopy for fancy bacteria: visualization and study of a toxin at the protein and single cell level (presented by Peter Kupferschmied)). 06.09.2012 Villars-sur-Ollon, Switzerland Keel Christoph;
CUSO Annual Retreat 2012 Talk given at a conference Fancy microscopy for fancy bacteria: visualization and study of a toxin at the protein and single cell level (presented by Peter Kupferschmied) 05.09.2012 Villars-sur-Ollon, Switzerland Keel Christoph;
14th International Symposium on Microbiola Ecology (ISME-14) Talk given at a conference Host-dependent induction of insect toxin production in a root-associated biocontrol pseudomonad. 19.08.2012 Copenhagen, Denmark Keel Christoph;
14th International Symposium on Microbiola Ecology (ISME-14) Poster How can plant-associated pseudomonads with antifungal activity become insect pathogens? (presented by Pascale Flury) 19.08.2012 Copenhagen, Denmark Keel Christoph; Flury Pascale; Maurhofer Monika; Péchy-Tarr Maria;
2012 International Congress on Invertebrate Pathology and Microbial Control and 45th Annual Meeting of the Society for Invertebrate Pathology Talk given at a conference Insecticidal activity of plant root-associated pseudomonads: host-specific expression of the Fit insect toxin (presented by Peter Kupferschmied). 05.08.2012 Buenos Aires, Argentina Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika;
Meeting of the Swiss Expert Committee for Biosafety Individual talk Plant-associated beneficial pseudomonads. 06.07.2012 Bern, Switzerland Maurhofer Monika;
70th Annual Meeting and Assembly of the Swiss Society for Microbiology Talk given at a conference When Pseudomonas fluorescens CHA0 launches its insect toxin production (presented by Peter Kupferschmied). 21.06.2012 St. Gallen, Switzerland Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika;
D.Day 2012, University of Lausanne Talk given at a conference When Pseudomonas fluorescens CHA0 launches its insect toxin production (presented by Peter Kupferschmied). 19.04.2012 Lausanne, Switzerland Keel Christoph; Péchy-Tarr Maria; Maurhofer Monika;
Meeting of the Swiss Society of Phytiatry Talk given at a conference Geschichten aus dem Untergrund: Wie nützliche Bakterien mit Pflanzen, Pathogenen und Schädlingen interagieren (presented by Monika Maurhofer and Peter Kupferschmied). 08.03.2012 Basel, Switzerland Maurhofer Monika; Péchy-Tarr Maria; Keel Christoph;


Communication with the public

Communication Title Media Place Year
Media relations: radio, television Fin du labour et couvert végétal, Radio reportage by Cécile Guerin Swiss Radio & Television RTS La 1ère – CFQD Western Switzerland 2015
Media relations: radio, television Soluzione radicale, Film by Cesare Bernasconi Swiss Television RSI LA1 – Il giardino di Albert Italian-speaking Switzerland 2014
Media relations: print media, online media Bakterien als Leibwächter – Des bactéries gardes du corps, Article by Fleur Daugey NF Horizonte No. 96 German-speaking Switzerland Italian-speaking Switzerland Western Switzerland 2013
Media relations: print media, online media Bodenbakterien für die Landwirtschaft, Article by Stephanie Lahrtz NZZ German-speaking Switzerland 2013
Media relations: print media, online media Schadinsekten mit Bakterien bekämpfen, Article by Maja Schaffner ETH LIfe German-speaking Switzerland 2012

Awards

Title Year
Society for Invertebrate Pathology Student Travel Award for oral presentation at the 2014 International Congress on Invertebrate Pathology, Mainz, Germany: Kupferschmied P, Péchy-Tarr M, Imperiali N, Maurhofer M, Keel C, Evolution of a sensor protein controlling production of an insecticidal toxin in plant-beneficial Pseudomonas protegens. 2014
Prize for best poster at the 2013 Autumn Meeting of the Swiss Society of Phytiatry. Kupferschmied P, Maurhofer M, Keel C. Wurzelassoziierte Pseudomonaden mit toxischer Aktivität gegenüber Insekten. 2013

Associated projects

Number Title Start Funding scheme
120121 Insecticidal activity in plant-associated beneficial pseudomonads: Molecular basis and ecological relevance 01.07.2008 Project funding
184666 Towards building microbial consortia for pest control: exploring adaptation to insect hosts and intraspecific diversity of pathogenicity and competition traits in insecticidal pseudomonads 01.05.2019 Project funding
159520 Molecular determinants contributing to insect and plant associated lifestyles of beneficial pseudomonads 01.05.2015 Project funding
158542 PSC Discovery Program for Youth 01.04.2015 Agora

Abstract

Background. Insect pests and fungal diseases cause major damage to agricultural crops and in particular those affecting below-ground plant parts are very difficult to ward off with chemical pesticides. Plant protection with beneficial soil bacteria is an ecologically sound alternative. We study biocontrol strains of Pseudomonas fluorescens that colonize roots and suppress fungal plant diseases. In the precedent project, we discovered that phylogenetically defined groups of these pseudomonads exhibit not only antifungal, but also potent oral and systemic insecticidal activity towards different lepidopteran pests and identified for the first time a locus encoding a novel insect toxin we termed Fit for P. fluorescens insecticidal toxin. We demonstrated that the Fit toxin contributes to anti-insect activity and obtained first insights into regulation of toxin production.Overall aim. In the first part of the project, we aim at unravelling regulatory mechanisms that control Fit insect toxin expression, activity and transport during interaction of P. fluorescens with the insect host and at identifying additional factors contributing to insecticidal activity. In the second part, we will investigate two possibilities of exploiting the Fit toxin as a novel means for pest control, i.e. by treating plant surfaces with Fit producing pseudomonads and by expressing Fit directly in the plant.Project keypoints. The following six tasks are envisaged. 1. Molecular analysis of locus-specific and global regulators and signals controlling Fit toxin expression in P. fluorescens during interaction with insects. 2. Investigation of Fit toxin transport and localization in P. fluorescens and implication of the Fit locus encoded protein secretion system. 3. Activity mapping of the Fit toxin to identify domains that are indispensable for insect toxicity and toxin transport. 4. Identification of additional traits contributing to anti-insect activity in plant-associated pseudomonads using a genomic expression library approach. 5. Evaluation of plant-colonizing Fit producing pseudomonads for the biological control of important root and leaf pests in plant assays. 6. Controlled expression of the Fit toxin or active fragments in Arabidopsis and evaluation of anti-pest properties of transgenic plants.Expected value. By studying the molecular basis of the regulation and activity of the Fit insect toxin and additional anti-insect factors during pseudomonad-insect interactions, we will generate fundamental new knowledge on the ecological role of insecticidal activity in plant-associated pseudomonads. Our discovery of potent oral anti-insect activity in plant-beneficial pseudomonads opens new possibilities for combined microbial pest and disease control, since these bacteria are very efficient, vector-independent below-ground plant parts colonizers. In a longer term perspective, the expression of the Fit toxin or active fragments in the plant may open up the possibility to develop new transgenic crops resistant to insect pests, offering an alternative to Bt crops.
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