VIEW ARTICLE

Physiology and Biochemistry

Serological and Electrophoretic Analysis of a Membrane Protein Extract of Xanthomonas campestris pv. campestris from Thailand. N. Thaveechai, Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow 83843, Present address: Department of Plant Pathology, Kasetsart University, Bangkok, Thailand; N. W. Schaad, Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow 83843. Phytopathology 76:139-147. Accepted for publication 23 August 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-139.

LiCl-extracted membrane proteins of 35 strains of Xanthomonas campestris pv. campestris from Thailand were characterized by serology and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Antisera were made to membrane proteins of seven strains. When membrane proteins of homologous strains were tested by Ouchterlony double diffusion, a single major line of precipitin always resulted. With some strains, up to three minor lines of precipitin also resulted. Two to four other minor lines of precipitin were present in immunoelectrophoresis. By testing with the major common line of precipitin, the strains of X. c. pv. campestris were grouped into three serovars--I, I-A, and II. When tested by immunofluorescent microscopy, all strains of X. c. pv. campestris were positive with immunoglobulin G to membrane proteins of the seven strains. None of 20 other xanthomonads or 11 other species reacted with the seven antisera by Ouchterlony double diffusion except four strains of X. campestris pv. vesicatoria and one strain of X. campestris pv. incanae (which cross-reacted in Ouchterlony double diffusion). All 24 bacteria were immunofluorescent negative except four strains of X. c. pv. vesicatoria and one strain each of X. c. pv. incanae and X. campestris pv. manihotis. SDS-PAGE profiles of membrane protein of X. c. pv. campestris were distinct from all the other bacteria tested. These results suggest that the membrane proteins of X. c. pv. campestris are distinct and therefore useful for identification and taxonomy.