GROUPING OF XANTHOMONAS-CAMPESTRIS PATHOVARS BY SDS-PAGE OF PROTEINS

A numerical analysis was performed on SDS-PAGE protein patterns of 307 Xanthomonas strains comprising all species and 27 X. campestris pathovars. The electrophoretic groupings corresponded in some, but not all cases with the existing pathovars. Six pathovars constituted distinct entities, comprising all strains investigated. These included X. campestris pv. campestris, X. campestris pv. graminis, X. campestris pv. hyacinthi, X. campestris pv. pelargonii, X. campestris pv. pruni and X. campestris pv. theicola. A great number of pathovars consisted of a homogeneous group from which only one or a few strains were aberrant. In two cases (X. campestris pv. ricini and X. campestris pv. vitians) even the pathovar reference strain was aberrant. Six pathovars from members of the plant family Fabaceae could not be differentiated from one another: X. campestris pv. phaseoli, X. campestris pv. phaseoli var. fuscans, X. campestris pv. cajani, X. campestris pv. vignicola, X. campestris pv. alfalfae and X. campestris pv. glycines. At least six X. campestris pathovars were heterogeneous, displaying two or more protein electrophoretic types: X. campestris pv. alfalfae, X. campestris pv. dieffenbachiae, X. campestris pv. juglandis, X. campestris pv. poinsettiicola, X. campestris pv. vesicatoria and X. campestris pv. vignicola. A database of SDS-protein patterns provides a valuable tool for the identification of unknown xanthomonads.