Article

The plant pathogen Erwinia amylovora produces acyl-homoserine lactone signal molecules in vitro and in planta

Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy.
FEMS Microbiology Letters (Impact Factor: 2.72). 01/2005; 241(2):179-83. DOI: 10.1016/j.femsle.2004.10.015
Source: PubMed

ABSTRACT We report for the first time the production of acyl homoserine lactones (AHLs) by Erwina amylovora, an important quarantine bacterial pathogen that causes fire blight in plants. E. amylovora produces one N-acyl homoserine lactone [a N-(3-oxo-hexanoyl)-homoserine lactone or a N-(3-hydroxy-hexanoyl)-homoserine lactone] quorum sensing signal molecule both in vitro and in planta (pear plant). Given the involvement of AHLs in plant pathogenesis, we speculate that AHL-dependent quorum sensing could play an important role in the regulation of E. amylovora virulence.

0 Followers
 · 
119 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Quorum sensing in Gram-negative bacteria is regulated by diffusible signal molecules called N-acyl-l-homoserine lactones (AHLs). These molecules are degraded by lactonases. In this study, six Bacillus simplex isolates were characterized and identified as a new quorum-quenching species of Bacillus. An aiiA gene encoding an AHL-lactonase was identified based on evidence that: (i) it showed high homology with other aiiA genes of Bacillus sp.; (ii) the deduced amino acid sequence contained two conserved regions, 104SHLHFDH111 and 165TPGHTPGH173, characteristic of the metallo-β-lactamase superfamily; and (iii) the protein had zinc-dependent AHL-degrading activity. Additionally, the expression of the aiiA gene was significantly up-regulated by 3-oxo-AHL. The AHL-lactonase inhibited multiplication of the 3-oxo-C6-AHL-producing plant pathogen Erwinia amylovora sy69 both in vitro and in planta. The results provide support for the use of the quorum-quenching functionality of B. simplex in the integrated control of the devastating fire blight pathogen.
    Plant Pathology 10/2013; 63(4). DOI:10.1111/ppa.12142 · 2.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The ability of sessile benthic egg masses to deter or prevent epibiosis is essential to the success of species that employ this life-history strategy. This study characterised the physical structure and bacterial communities on the surface of egg masses from the Siphonariid mollusc Siphonaria diemenensis (Quoy & Gaimard, 1833). Egg masses at the veliger stage of development were collected from two intertidal sites in the Gulf St. Vincent, South Australia. Physical structure was assessed using a combination of light microscopy and scanning electron microscopy. Egg mass surfaces were characterised by wave-like elevations 1–3 μm apart, fouled only by cocci, and longitudinal ridges (5–20 μm) fouled by a diversity of microorganisms and dense exopolymeric substance. Bacteria from the surface of egg masses and adjacent rock substratum were then isolated using standard culture procedures. The biochemical profiles of the isolates were used, along with Gram stain and visual morphological observations, to identify the bacteria. Eight species of bacteria were isolated and the composition of culturable epibiont communities from the egg mass was found to be significantly different from those found on the adjacent substrata. One species of bacterium on egg masses exhibited antibacterial activity in mixed culture and was identified as Bacillus psychrodurans using PCR of the partial 16S rRNA gene and sequence alignment on the GenBank database. Chemical extraction was performed on ‘clean’ and ‘fouled’ eggs and antibacterial activity was assessed against the marine pathogen Vibrio harveyi using the disc diffusion assay. Extracts from the cleaned egg masses were found to inhibit the growth of V. harveyi, whilst the fouled egg masses and extracts from the epibionts showed no antibacterial activity. However, extracts from the supernatant and cell pellet from the cultured B. psychrodurans exhibited antibacterial activity against V. harveyi and two human pathogens, Staphylococcus aureus and Escherichia coli. The results obtained in this study suggest that the surfaces of S. diemenensis egg masses are selective towards coccoid bacteria, which may result from a combination of physical structure and chemical antimicrobial properties, with further competitive interactions possibly occurring between the epibionts post settlement.
    Journal of Experimental Marine Biology and Ecology 11/2012; s 432–433:138–147. DOI:10.1016/j.jembe.2012.07.018 · 2.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Erwinia piriflorinigrans is a necrotrophic pathogen of pear reported from Spain that destroys flowers but does not progress further into the host. We sequenced the complete genome of the type strain CFBP 5888(T) clarifying its phylogenetic position within the genus Erwinia, and indicating a position between its closest relative, the epiphyte Erwinia tasmaniensis and other plant pathogenic Erwinia spp. (i.e., the fire blight pathogen E. amylovora and the Asian pear pathogen E. pyrifoliae). Common features are the type III and type VI secretion systems, amylovoran biosynthesis and desferrioxamine production. The E. piriflorinigrans genome also provided the first evidence for production of the siderophore chrysobactin within the genus Erwinia sensu stricto, which up to now was mostly associated with phytopathogenic, soft-rot Dickeya and Pectobacterium species. Plasmid pEPIR37, reported in this strain, is closely related to small plasmids found in the fire blight pathogen E. amylovora and E. pyrifoliae. The genome of E. piriflorinigrans also gives detailed insights in evolutionary genomics of pathoadapted Erwinia.
    Systematic and Applied Microbiology 05/2013; DOI:10.1016/j.syapm.2013.04.003 · 3.31 Impact Factor

Preview

Download
1 Download