METABOLITES OF ERWINIA .15. PROFERROROSAMINES AND PHYTOPATHOGENICITY IN ERWINIA SPP

Proferrorosamine A (pFR A) of the plant pathogenic bacterium Erwinia r hapontici was shown to inhibit growth of wheat and cress seedlings at the greater than or equal to 10 ppm level, When the seeds were continu ously exposed to 100 ppm pFR A, the germination of cress and wheat see ds was inhibited up to 90% and 80%, respectively, The inhibition could be reversed through addition of equimolar amounts of ferrous iron, wh ich indicates that the strong iron chelating capability of pFR A is re sponsible for the observed effect, The Fe(II) in the corresponding iro n complex, ferrorosamine A, was found to be remarkably resistant towar ds oxidation by hydrogen peroxide and therefore redox-cycling in the H aber-Weiss cycle, It is thus conceivable that PFR A may also attenuate the generation of reactive hydroxyl radicals during the resistant and wound reaction, The apparent correlation between proferrorosamine pro duction and virulence in erwiniae was further corroborated through the analysis of Erwinia persicinus, a newly described species, Using elec trospray ionization mass spectrometry, E. persicinus was shown to prod uce pFR A and pFR B, and preliminary evidence for the phytopathogenici ty of E. persicinus was found in cress, Inhibition of wheat seedlings by E. persicinus could not be demonstrated, but this may be due to tec hnical difficulties or different host specificities. Taken together, o ur results indicate that the phytopathogenicity of E. rhapontici and E . persicinus may, as least in part, be due to the release of proferror osamines.