Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2008
Publication Date: 6/2/2008
Citation: Loper, J.E., Paulsen, I., Bruck, D.J., Pechy-Tarr, M., Keel, C., Gross, H. 2008. Genomics of secondary metabolite production by Pseudomonas fluorescens Pf-5. Phytopathology. S94. Interpretive Summary:
Technical Abstract: The rhizosphere bacterium Pseudomonas fluorescens Pf-5 is known to produce six secondary metabolites, and the genomic sequence of Pf-5 revealed three additional gene clusters, which encode for the biosynthesis of unknown natural products but contain conserved sequences of genes encoding for non-ribosomal peptide synthetases or polyketide synthases. Natural products synthesized from two of these orphan gene clusters have since been identified. Orfamide A, a novel cyclic lipopeptide produced by Pf-5, contributes to swarming motility of Pf-5 and has the capacity to lyse zoospores produced by phytopathogenic Phytophthora spp. Several analogs of rhizoxin, a macrocyclic lactone with antifungal activity, are synthesized from a large biosynthetic gene cluster in the Pf-5 genome. Linked to the rhizoxin biosynthetic locus is a cluster of genes encoding for an insect toxin termed FitD, which is related to Mcf (for “makes caterpillars floppy”) produced by Photorhabdus luminescens, an inhabitant of the gut of entomopathogenic nematodes in the genus Heterorhabditis.. If injected into the hemocoel, Pf-5 kills caterpillars of tobacco hornworms (Manduca sexta) whereas an fitD mutant of Pf-5 is less virulent. An oligonucleotide array representing each ORF in the Pf-5 genome has been developed and is being utilized to explore the influence of the global regulatory genes gacA, rpoS and ptsP on transcription of secondary metabolite biosynthesis and efflux genes. The genomic sequence of P. fluorescens Pf-5 provides a variety of insights and into this organism’s interactions with plants and other organisms in the environment.