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Serotypes of Xanthomonas vesicatoria Unrelated to Its Pathotypes. R. Charudattan, Postdoctoral Associate, Plant Pathology Department, University of Florida, Gainesville 32601; R. E. Stall(2), and D. L. Batchelor(3). (2)(3)Professor, and Laboratory Technologist, respectively, Plant Pathology Department, University of Florida, Gainesville 32601. Phytopathology 63:1260-1265. Accepted for publication 3 April 1973. DOI: 10.1094/Phyto-63-1260.

Two serotypes, based on the presence or absence of certain precipitin bands in gel-diffusion plates, were designated among 72 isolates of Xanthomonas vesicatoria. These indicators were the one to three arclike bands formed close to antigen wells by nonheated antigens of either serotype against its homologous-type serum that were generally lacking with serum of heterologous type. Antisera of types I and II formed fast diffusible components with heated antigen preparations. With type I sera and heated type I antigens, these components formed a thick precipitin band, whereas heated type II antigens gave a weak precipitin reaction. Such distinction in the fast diffusible components could not be seen with type II serum; both types formed similar bands. However, the two types were distinguished by their specific agglutinin reactions. The fast diffusible components of types I and II were associated with soluble bacterial cell-surface compounds. There was no correlation between serology and pathology of X. vesicatoria isolates. The tomato and pepper isolates included both serotypes; thus, the tomato and pepper isolates could not be distinguished on the basis of serological tests. Also, the ability of isolates to hydrolyze starch, their resistance to streptomycin, or age in culture had no correlation with the serotypes.