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Genomic Fingerprinting of Two Pathovars of Phytopathogenic Bacteria by Rare-Cutting Restriction Enzymes and Field Inversion Gel Electrophoresis. Donald A. Cooksey, Associate professor, Department of Plant Pathology, University of California, Riverside 92521; James H. Graham, Associate professor, Citrus Research and Education Center, University of Florida, Lake Alfred 33850. Phytopathology 79:745-750. Accepted for publication 21 February 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/Phyto-79-745.

Several restriction endonucleases cut infrequently in the genomes of Pseudomonas syringae and pathovars of Xanthomonas campestris, and distinctive patterns of large DNA fragments were generated using field inversion gel electrophoresis. The resolution of genomic DNA fragments by this method permitted standard analyses of genetic relationships between strains by means of dissimilarity coefficients and cluster analyses. We examined 10 strains of P. s. tomato and identified two groups that could be readily distinguished from each other. Strains of other pathovars of P. syringae had genomic fingerprints very different from those of the strains of P. s. tomato. The strains of X. c. vesicatoria all had similar genomic fingerprints, but distinctive subgroups within the pathovar could be identified. Strains of other pathovars of X. campestris also had very different genomic fingerprints from the strains of X. c. vesicatoria.