Comparison and utilization of different PCR-based approaches for molecular typing of Pseudomonas syringae pv. actinidiae strains from Italy

Over the last few years, a severe bacterial disease affecting kiwifruit has been reported in Italy. Its causal agent was identified as Pseudomonas syringae pv. actinidiae. For epidemiological purposes, we evaluated the discriminatory power of various PCR-based fingerprinting approaches. Profiles were generated by rep-PCR ((GTG)5-PCR), IS50-PCR and RAPD, from a wide collection of Italian, Korean and Japanese strains. The genetic relationships between strains of pv. actinidiae and strains from related pathovars were investigated. No differences between Italian strains were identified. However, some differences were identified between Italian strains and strains from Japan and Korea. The other pathovars clustered separately, and pv. theae was always more closely related to pv. actinidiae than the others. In general, the results obtained with the different methods were in good agreement, with RAPD showing the highest values of divergence between groups.