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Molecular characterization of the Enterobacter cloacae-onion (Allium cepa) interaction and the search for pathogenicity determinants

Enterobacter cloacae causes Enterobacter decay of onion bulbs in storage and is an emerging bacterial pathogen of onion (Allium cepa). E. cloacae is ubiquitous in nature and is an opportunistic pathogen of humans. A multilocus phytogeny demonstrated that strains of E. cloacae obtained from onion bul...

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Bibliographic Details
Published in:Phytopathology 2010-06, Vol.100 (6), p.S53-S53
Main Authors: Humann, J L, Dossey, S, Pena, J, Peterson, N, Bates, A A, Liesche, R, Peever, T, Schroeder, B K
Format: Article
Language:English
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Summary:Enterobacter cloacae causes Enterobacter decay of onion bulbs in storage and is an emerging bacterial pathogen of onion (Allium cepa). E. cloacae is ubiquitous in nature and is an opportunistic pathogen of humans. A multilocus phytogeny demonstrated that strains of E. cloacae obtained from onion bulbs occupy a well-supported clade distinct from isolates of medical origin. Little is known about the E. cloacae-onion interaction and our investigations have demonstrated that E. cloacae can move through onion leaf tissue at a rate of approx. 2 cm per week. In addition, preliminary evidence suggests that E. cloacae biofilm mutants move faster in planta than wild-type strains. SEM studies have indicated that a matrix forms in the phloem of E. cloacae inoculated onion potentially reducing the size of the plant. Analysis of E. cloacae culture filtrates determined that a necrosis-inducing product is secreted into the medium that is both heat-instable and sensitive to proteinase K. In an effort to identify genes involved in the production of this necrosis-inducing product and pathogenicity, an onion slice assay was developed. This assay enabled the high-throughput screening of mini-Tn5 mutants of E. cloacae and the identification of putative pathogenicity-minus mutants. These mutants are currently being characterized and genetic analysis of these E. cloacae mutants will be discussed.
ISSN:0031-949X