Submitted to: International Congress on Molecular Plant-Microbe Interactions
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2009
Publication Date: 7/19/2009
Citation: Loper, J.E., Kidarsa, T.A., Gross, H., Paulsen, I. 2009. Genomic analysis of secondary metabolite production by Pseudomonas fluorescens. International Congress on Molecular Plant-Microbe Interactions Program Book. p.6. Interpretive Summary:
Technical Abstract: Pseudomonas fluorescens is a diverse bacterial species known for its ubiquity in natural habitats and its production of secondary metabolites. The high degree of ecological and metabolic diversity represented in P. fluorescens is reflected in the genomic diversity displayed among strains. Certain strains live in association with plants, protecting them from infection by plant pathogens due, in part, to their production of antibiotics and extracellular enzymes. Nearly 6% of the genome of the biological control bacterium P. fluorescens Pf-5 is devoted to the biosynthesis of secondary metabolites. With few exceptions, these biosynthetic gene clusters are present in strain-specific regions of the genome. Many orphan gene clusters, which encode for the biosynthesis of unknown natural products, have also been identified in strain-specific regions of the Pf-5 genome. Through combined bioinformatic and chemical analyses, the products of several orphan gene clusters have been identified and characterized. The novel cyclic lipopeptide orfamide A lyses zoospores produced by phytopathogenic Phytophthora spp. The FitD toxin, which contributes to the newly-discovered insecticidal activity of Pf-5, and several analogs of rhizoxin, a macrocyclic lactone with antifungal activity, are also synthesized from gene clusters in strain-specific regions of the Pf-5 genome. To better understand mechanisms of biological control, the transcriptome of Pf-5 grown on seeds has been determined in microarray experiments, highlighting secondary metabolism genes expressed in situ by the bacterium. Comparative and functional genomics of P. fluorescens have revealed novel secondary metabolites and new insights into the biology of the bacterium.