EASTERN AND SOUTHERN AFRICAN STRAINS OF XANTHOMONAS-CAMPESTRIS PV VASCULORUM ARE DISTINGUISHABLE BY RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM OF DNA AND POLYACRYLAMIDE-GEL ELECTROPHORESIS OF MEMBRANE-PROTEINS

Thirty strains of Xanthomonas campestris pv. vasculorum were examined using restriction fragment length polymorphism (RFLP) of genomic DNA and polyacrylamide gel electrophoresis (PAGE) of membrane proteins. Previous reports suggested the existence of two geographical strains of this pathogen, occurring primarily in eastern and southern Africa, Seventeen southern African strains from South Africa and Zimbabwe formed an apparent clonal population with distinct and unique RFLP patterns and membrane protein profiles. Similarly, 11 eastern African strains from Mauritius and Reunion and two from Australia were also related, indicating the possible existence of two distinct organisms separated by geographical locality but otherwise involved in the same disease. Our data confirm the long-held hypothesis that eastern African strains of X. c. pv. vasculorum are distinct from the southern African strains. The fact that these two distinct strains cause the same disease, gumming disease of sugar cane, suggests the possible independent development of the pathogen in these two localities.