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Physiology and Biochemistry

Proteins Unique to Phenotypically Distinct Groups of Xanthomonas campestris pv. vesicatoria Revealed by Silver Staining. H. Bouzar, Gulf Coast Research & Education Center, University of Florida, Bradenton 34203. The first author is an exchange scholar from Université de Blida, Algeria.; J. B. Jones(2), G. V. Minsavage(3), R. E. Stall(4), and J. W. Scott(5). (2)(5)Gulf Coast Research & Education Center, University of Florida, Bradenton 34203; (3)(4)Plant Pathology Department, University of Florida, Gainesville 36211. Phytopathology 84:39-44. Accepted for publication 5 October 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-39.

Silver staining of sodium dodecyl sulfate-lysed cells of Xanthomonas campestris pv. vesicatoria electrophoretically separated in polyacrylamide gel revealed broad, dark gray bands in the low molecular weight region. The molecular weight of these bands was characteristic for each of the two major phenotypic groups identified in our X. c. vesicatoria collection. A 32- to 35-kDa band, designated α, was present in 192 of 197 tomato race 1 strains; whereas, a 25- to 27-kDa band, designated ?, was present in all 55 strains of tomato race 2. Race 1 strains expressing an ? band were unable to hydrolyze starch (Amy^–), and very few degraded pectate (Pec^–). In contrast, most race 2 strains were Amy⁺ and Pec⁺. The α and β bands, which are unique to each of the X. c. vesicatoria subpopulations, were not revealed when the Coomassie blue or copper staining protocols were used and were characterized as heat-stable proteins. Silver staining of protein profiles and testing for amylolytic activity of the bacterium are relatively simple tests that can help assign uncharacterized strains to each X. c. vesicatoria phenotypic group.