Serological Specificity of Xanthomonas campestris pv. oryzae

Abstract

By means of agglutination test with antisera produced against three different serovars of Xanthomonas campestris pv. oryzae, positive reaction was observed not only with the antigens belonging to homologous pathovars but also with those of other pathovars such as X. campestris pv. citri, X. campestris pv. hordei, X. campestris pv. vesicatoria and X. campestris pv. vitians, suggesting that they have common antigens. In gel diffusion test, however, the antisera showed specific reactions. Among antisera produced against three serovars of X. campestris pv. oryzae, the antiserum against Q7472 (serovar A) produced bands only with intact cells of the isolates belonging to homologous serovar, but antisera of Q7502 (serovar B-I) and N5837 (serovar B-II) produced bands with all species of xanthomonads and some of the other genera as well. The antiserum produced against sonicated cells of the isolate Q7472 produced bands with intact cells of all xanthomonads, but not with any species belonging to Pseudomonas, Bacillus, Rhizobium and Corynebacterium used in this experiment. The antiserum produced against sonicated cells of X. campestris pv. oryzae Q7472 showed positive reaction specifically with X. campestris pv. oryzae isolates, when antigens were previously treated by heating. Serovars B-I and B-II of X. campestris pv. oryzae showed severe autoagglutination in CaCl₂ solution, but serovar A did not, suggesting possible differentiation of these serovars from each other or from other xanthomonads by this method.