Characterization of Italian populations of Xanthomonas campestris pv. campestris using primers based on DNA repetitive sequences

Xanthomonas campestris pv. campestris (Xcc) is the causal agent of vascular blackening of crucifers. One-hundred and forty-one Xcc strains, isolated from different Central and Southern Italian regions and crucifer plants, were characterized for DNA polymorphism by PCR, using primers based on repetitive sequences. By M13-PCR, all the Xcc strains, except for two, were distributed in three main clusters: α, with similarity index (SI) of 0.78, containing 70 strains grouped in 19 haplotypes; β (SI = 0.80) containing 54 strains grouped in 17 haplotypes; γ (SI = 0.75) containing 15 Xcc strains grouped in 6 haplotypes. By BOX-PCR, all the Xcc strains were distributed in three main clusters: α (SI = 0.58) containing 102 strains distributed in 9 haplotypes; β (SI = 0.45), including 24 strains distributed in 9 haplotypes; γ (SI = 0.37), including 15 Xcc strains distributed in 3 haplotypes. A very large variability was observed in these Italian populations of Xanthomonas campestris pv. campestris, especially using M13-PCR. No obvious relations were observed between the strains contained in each cluster, sub-cluster or haplotype and their geographic origin or host plant.