title: Identification of the bacterial superoxide dismutase (SodM) as plant-inducible elicitor of an oxidative burst reaction in tobacco cell suspension cultures.
abstract: Three of the most abundant proteins (OmpW, MopB and SodM) of the extracellular proteome of Xanthomonas campestris pv. campestris were analysed in a luminol-based oxidative burst assay to identify novel pathogen-associated molecular patterns (PAMP). Tobacco cell suspension cultures were used as a model system to monitor elicitor induced plant defence reaction. The candidate proteins were isolated from two-dimensional gels prior to application to the oxidative burst assay. The superoxide dismutase (SodM) was the only isolated protein that could elicit a notable hydrogen peroxide (H2O2) production in tobacco cell cultures indicating the initiation of plant defence. An alignment of the SodM sequences from X. campestris pv. campestris and Escherichia coli revealed 55.7% identity and 29% of the sequence were substitutions for amino acids with similar physico-chemical properties. By using a commercially available purified E. coli derived SodM preparation, it was possible to show that the amino acid sequence of this protein is responsible for the elicitation of an oxidative burst reaction in the tobacco cell culture model. This suggests that the bacterial superoxide dismutase is a novel pathogen-associated molecular pattern. The minimal elicitor active sequence, however, is still elusive.
authors.affiliation: Department of Genetics, Faculty of Biology, Bielefeld University, P.O. Box 100131, D-33501 Bielefeld, Germany. steven.watt@genetik.uni-biefeld.de
authors.forename: Steven Alexander
authors.initials: SA
authors.lastname: Watt
authors.forename: Verena
authors.initials: V
authors.lastname: Tellström
authors.forename: Thomas
authors.initials: T
authors.lastname: Patschkowski
authors.forename: Karsten
authors.initials: K
authors.lastname: Niehaus
mesh_terms: D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D006861:Hydrogen Peroxide / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D013482:Superoxide Dismutase / Q000378:metabolism*; D014026:Nicotiana / Q000378:metabolism* / Q000382:microbiology; D016959:Xanthomonas campestris / Q000201:enzymology*
chemical_list: D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase