GENETIC-RELATIONSHIPS AMONG STRAINS OF XANTHOMONAS-FRAGARIAE BASED ONRANDOM AMPLIFIED POLYMORPHIC DNA PCR, REPETITIVE EXTRAGENIC PALINDROMIC PCR, AND ENTEROBACTERIAL REPETITIVE INTERGENIC CONSENSUS PCR DATA AND GENERATION OF MULTIPLEXED PCR PRIMERS USEFUL FOR THE IDENTIFICATIONOF THIS PHYTOPATHOGEN

Genetic relationships among 25 isolates of Xanthomonas fragariae from diverse geographic regions were determined by three PCR methods that r ely on different amplification priming strategies: random amplified po lymorphic DNA (RAPD) PCR, repetitive extragenic palindromic (REP) PCR, and enterobacterial repetitive intergenic consensus (ERIC) PCR, The r esults of these assays are mutually consistent and indicate that patho genic strains are very closely related to each other, RAPD, ERIC, and REP PCR assays identified nine, four, and two genotypes, respectively, within X, fragariae isolates, A single nonpathogenic isolate of X. fr agariae was not distinguishable by these methods, The results of the P CR assays were also fully confirmed by physiological tests, There was no correlation between DNA amplification product patterns and geograph ic sites of isolation, suggesting that this bacterium has spread large ly through exchange of infected plant germ plasm, Sequences identified through the RAPD assays were used to develop three primer pairs for s tandard PCR assays to identify X. fragariae. In addition, we developed a stringent multiplexed PCR assay to identify X. fragarine by simulta neously using the three independently derived sets of primers specific for pathogenic strains of the bacteria.