title: Insect pathogenicity in plant-beneficial pseudomonads: phylogenetic distribution and comparative genomics.
abstract: Bacteria of the genus Pseudomonas occupy diverse environments. The Pseudomonas fluorescens group is particularly well-known for its plant-beneficial properties including pathogen suppression. Recent observations that some strains of this group also cause lethal infections in insect larvae, however, point to a more versatile ecology of these bacteria. We show that 26 P. fluorescens group strains, isolated from three continents and covering three phylogenetically distinct sub-clades, exhibited different activities toward lepidopteran larvae, ranging from lethal to avirulent. All strains of sub-clade 1, which includes Pseudomonas chlororaphis and Pseudomonas protegens, were highly insecticidal regardless of their origin (animals, plants). Comparative genomics revealed that strains in this sub-clade possess specific traits allowing a switch between plant- and insect-associated lifestyles. We identified 90 genes unique to all highly insecticidal strains (sub-clade 1) and 117 genes common to all strains of sub-clade 1 and present in some moderately insecticidal strains of sub-clade 3. Mutational analysis of selected genes revealed the importance of chitinase C and phospholipase C in insect pathogenicity. The study provides insight into the genetic basis and phylogenetic distribution of traits defining insecticidal activity in plant-beneficial pseudomonads. Strains with potent dual activity against plant pathogens and herbivorous insects have great potential for use in integrated pest management for crops.
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
authors.forename: Pascale
authors.initials: P
authors.lastname: Flury
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
authors.forename: Nora
authors.initials: N
authors.lastname: Aellen
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
authors.forename: Beat
authors.initials: B
authors.lastname: Ruffner
authors.affiliation: Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
authors.forename: Maria
authors.initials: M
authors.lastname: Péchy-Tarr
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
authors.forename: Shakira
authors.initials: S
authors.lastname: Fataar
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.|Laboratory of Experimental Entomology, Institute of Biology, University of Latvia, Riga, Latvia.
authors.forename: Zane
authors.initials: Z
authors.lastname: Metla
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
authors.forename: Ana
authors.initials: A
authors.lastname: Dominguez-Ferreras
authors.affiliation: Institute of Medical Microbiology, University of Zurich, Zürich, Switzerland.
authors.forename: Guido
authors.initials: G
authors.lastname: Bloemberg
authors.affiliation: Institute of Veterinary Bacteriology, University of Bern, Bern, Switzerland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Frey
authors.affiliation: Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Goesmann
authors.affiliation: Department of Microbial Ecology, Netherlands Institute of Ecology, NIOO-KNAW, Wageningen, The Netherlands.
authors.forename: Jos M
authors.initials: JM
authors.lastname: Raaijmakers
authors.affiliation: Environmental Genomics and Systems Biology Research Group, Institute for Natural Resource Sciences, Zürich University of Applied Sciences, Wädenswil, Switzerland.
authors.forename: Brion
authors.initials: B
authors.lastname: Duffy
authors.affiliation: Laboratory of Phytopathology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
authors.forename: Monica
authors.initials: M
authors.lastname: Höfte
authors.affiliation: Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Blom
authors.affiliation: Environmental Genomics and Systems Biology Research Group, Institute for Natural Resource Sciences, Zürich University of Applied Sciences, Wädenswil, Switzerland.
authors.forename: Theo H M
authors.initials: TH
authors.lastname: Smits
authors.affiliation: Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Keel
authors.affiliation: Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
authors.forename: Monika
authors.initials: M
authors.lastname: Maurhofer
mesh_terms: D000818:Animals; D023281:Genomics; D058507:Host Specificity; D007814:Larva / Q000382:microbiology; D007915:Lepidoptera / Q000382:microbiology*; D010802:Phylogeny; D010944:Plants / Q000382:microbiology*; D011549:Pseudomonas / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence