title: Characterization of Toxin Complex Gene Clusters and Insect Toxicity of Bacteria Representing Four Subgroups of Pseudomonas fluorescens.
abstract: Ten strains representing four lineages of the Pseudomonas fluorescens group (P. chlororaphis, P. corrugata, P. koreensis, and P. fluorescens subgroups) were evaluated for toxicity to the tobacco hornworm Manduca sexta and the common fruit fly Drosophila melanogaster. The three strains within the P. chlororaphis subgroup exhibited both oral and injectable toxicity to the lepidopteran M. sexta. All three strains have the gene cluster encoding the FitD insect toxin and a ΔfitD mutant of P. protegens strain Pf-5 exhibited diminished oral toxicity compared to the wildtype strain. Only one of the three strains, P. protegens Pf-5, exhibited substantial levels of oral toxicity against the dipteran D. melanogaster. Three strains in the P. fluorescens subgroup, which lack fitD, consistently showed significant levels of injectable toxicity against M. sexta. In contrast, the oral toxicity of these strains against D. melanogaster was variable between experiments, with only one strain, Pseudomonas sp. BG33R, causing significant levels of mortality in repeated experiments. Toxin complex (Tc) gene clusters, which encode insecticidal properties in Photorhabdus luminescens, were identified in the genomes of seven of the ten strains evaluated in this study. Within those seven genomes, six types of Tc gene clusters were identified, distinguished by gene content, organization and genomic location, but no correlation was observed between the presence of Tc genes and insect toxicity of the evaluated strains. Our results demonstrate that members of the P. fluorescens group have the capacity to kill insects by both FitD-dependent and independent mechanisms.
authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America.
authors: Lorena I
authors: LI
authors: Rangel
authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America.|Agricultural Research Service, US Department of Agriculture, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America.
authors: Marcella D
authors: MD
authors: Henkels
authors: Agricultural Research Service, US Department of Agriculture, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America.
authors: Brenda T
authors: BT
authors: Shaffer
authors: Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America.
authors: Francesca L
authors: FL
authors: Walker
authors: Agricultural Research Service, US Department of Agriculture, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America.
authors: Edward W
authors: EW
authors: Davis
authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America.
authors: Virginia O
authors: VO
authors: Stockwell
authors: Agricultural Research Service, US Department of Agriculture, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America.
authors: Denny
authors: D
authors: Bruck
authors: Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America.
authors: Barbara J
authors: BJ
authors: Taylor
authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America.|Agricultural Research Service, US Department of Agriculture, Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America.
authors: Joyce E
authors: JE
authors: Loper
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D004331:Drosophila melanogaster; D018402:Manduca; D005810:Multigene Family; D011551:Pseudomonas fluorescens / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins