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Ecology and Epidemiology

Motility of Pseudomonas syringae pv. glycinea and its Role in Infection. D. R. Hattermann, Former graduate research assistant, Department of Plant Pathology, University of Illinois at Urbana-Champaign 61801; S. M. Ries, associate professor, Department of Plant Pathology, University of Illinois at Urbana-Champaign 61801. Phytopathology 79:284-289. Accepted for publication 17 August 1988. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-284.

Flagellar motility in Pseudomonas syringae pv. glycinea, as determined by capillary assay, is optimal at growth temperatures of 17–27 C and inhibited by higher temperatures. Motility is optimal at pH 6–7 and in the presence of 10^–5 M ethylenediamine tetraacetic acid, but reduced motility occurs in the absence of and in the presence of higher concentrations of EDTA. Motility is stimulated by exogenous energy sources such as glycerol, sodium citrate, and asparagine in the presence of oxygen. P. s. glycinea is attracted to leaf extracts from both susceptible and resistant soybean cultivars. A nonmotile strain (Nm7), obtained by mutagenesis with ethyl methanesulfonate, and its motile revertant (Mr7) were as pathogenic as the wild-type strain on susceptible soybean (Wells II) leaves. Externally applied inoculum (leaf dip) of Mr7 resulted in significantly more lesions on susceptible soybean leaves (water-soaked by vacuum infiltration) than did Nm7 at a concentration of 4 × 10⁵ colony-forming units per milliliter.