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

Xanthomonas campestris pv. vesicatoria strains from a worldwide collec tion were assigned to the A or B group by testing for amylolytic activ ity and the presence of the alpha or beta protein band. Cluster analys es of serological, carbon substrate utilization, and fatty acid compos ition data resulted in dendrograms with interspersed clusters of A and B strains, suggesting that the strain populations within each group a re heterogeneous. However, further analysis of the data identified fea tures unique to members of each group. Two monoclonal antibodies react ed only with group A strains, and two reacted only with group B strain s. Reactivity patterns further subdivided each group into three serova rs. 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. T he only substrate that discriminated between strains of the two groups was cis-aconitate, which was utilized by A but not by B strains. Acco rding to these assays, the neopathotype strain of X. c. vesicatoria (A TCC 35937) belongs to the B group. The bacterial pathogen Pseudomonas gardneri shares characteristics of both A and B strains; thus, it is a pparently related to X. c. vesicatoria. The dendrograms generated from cluster analyses of carbon substrate utilization patterns and fatty a cid 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 aff iliations of the X. c. vesicatoria strains tested were determined with tomato and pepper differential genotypes. The reaction on tomato line s distinguished the two groups as separate races: A strains were tomat o race 1 (i.e., T1), and B strains were T2. Except for 14 T2P3 strains , pepper race strains were affiliated with the A group.