Immunodiffusion analysis of isolates of Xanthomonas cyamopsidis.

Immunodiffusion analysis of intact, sonically treated, and sonically treated and heat-treated cell antigen preparations of isolates of races 0 and 1 of Xanthomonas cyamopsidis of guar, Cyamopsis tetragonoloba, indicated that these races differ from one another antigenically. The differentiating precipitin reactions are believed to have been brought about by specific heat-stable surface antigens, possibly similar to lipopolysaccaride somatic antigens of other slime-producing xanthomonads. Because differences in host reaction to inoculation with the two isolates of race 1 were known to be minor, these isolates are considered to represent serotypes of the race rather than distinct separate races. This conclusion is supported by the antigenic behavior of isolates 14 and 19 to antiserum 19. The applicability of immunodiffusion analysis for the study of pathogenic variability in X. cyamopsidis is demonstrated.