RESUMO
The genetic diversity of 55 xanthomonad strains isolated from passion fruit plants (Passiflora spp.) and identified as Xanthomonas campestris pv. passiflorae was initially assessed by randomly amplified polymorphic DNA (RAPD) analysis. The strains showed a high level of polymorphism with almost unique fingerprints. Fifteen clusters with a similarity of approximately 70% were identified, three of which were prevalent. There was a correlation between the clusters and the geographic origin of the strains. A representative strain of each cluster, together with the pathovar reference strain, were used to verify the relationships of these strains to 18 Xanthomonas species and Pseudomonas syringae pv. passiflorae. All Xanthomonas species yielded a unique RAPD profile and no consistent relatedness to the X. campestris pv. passiflorae strains was observed. Amplification products were also analysed by repetitive (rep) primers (BOX, ERIC and REP), RFLP of the 16S-23S rDNA intergenic spacer and SDS-PAGE of whole-cell proteins. All of these approaches generated profiles characteristic for each Xanthomonas species but the taxonomic position of the X. campestris pv. passiflorae strains could not be unequivocally assigned. Finally, DNA-DNA hybridization allowed a sound taxonomic allocation of the strains to Xanthomonas axonopodis pv. passiflorae.
