PHYSIOLOGICAL, CHEMICAL, SEROLOGICAL, AND PATHOGENIC ANALYSES OF A WORLDWIDE COLLECTION OF XANTHOMONAS-CAMPESTRIS PV VESICATORIA STRAINS

Xanthomonas campestris pv. vesicatoria strains from a worldwide collection were assigned to the A or B group by testing for amylolytic activity and the presence of the alpha or beta protein band. Cluster analyses of serological, carbon substrate utilization, and fatty acid composition data resulted in dendrograms with interspersed clusters of A and B strains, suggesting that the strain populations within each group are heterogeneous. However, further analysis of the data identified features unique to members of each group. Two monoclonal antibodies reacted only with group A strains, and two reacted only with group B strains. Reactivity patterns further subdivided each group into three serovars. Differentiation of A and B strains by their fatty acid composition was primarily based on lower amounts of 15:0 ante-iso in A strains. The only substrate that discriminated between strains of the two groups was cis-aconitate, which was utilized by A but not by B strains. According to these assays, the neopathotype strain of X. c. vesicatoria (ATCC 35937) belongs to the B group. The bacterial pathogen Pseudomonas gardneri shares characteristics of both A and B strains; thus, it is apparently related to X. c. vesicatoria. The dendrograms generated from cluster analyses of carbon substrate utilization patterns and fatty acid profiles of X. c. vesicatoria strains included several pathovars, indicating that strains making up this taxon were as diverse in their carbon substrate utilization ability and fatty acid composition as the strains of the different X. campestris pathovars tested. The race affiliations of the X. c. vesicatoria strains tested were determined with tomato and pepper differential genotypes. The reaction on tomato lines distinguished the two groups as separate races: A strains were tomato race 1 (i.e., T1), and B strains were T2. Except for 14 T2P3 strains, pepper race strains were affiliated with the A group.