SUMMARY

The amplified fragment length polymorphism (AFLP) technique was applied to 109 strains of pv. pruni and one strain of pv. juglandis of the species Xan-thomonas arboricola and to five strains of other Xan-thomonas species. Groups of 12 and 41 strains of pv. pruni were isolated at the same time from fruit lesions in two peach orchards in the province of Verona (Italy). The other strains of pv. pruni were from different geo-graphic areas and/or host plants. The EcoRI/MseI and EOO/M02 pairs were used as restriction enzymes and selective amplification primers. Comparison of the AFLP profiles showed that the X. arboricola pv. pruni profile could be reliably distinguished from those of pv. juglandis and the other five species; 108 out of 109 strains of X. arboricola pv. pruni were included in the main cluster (SD = 0.93). This was divided into 3 sub-groups: I (SD = 0.982; 73 strains); II (SD = 0.979; 32 strains); III (SD = 0.990; 3 strains). Another subgroup, IV, with just one strain clustered with the other 3 sub-groups at SD = 0.89. Isolates from the same peach or-chard fell within subgroups I and II, as did strains from other geographic areas or from different host plants. The technique used did not have sufficient resolution to distinguish homogeneous groups of pv. pruni of X. ar-boricola on the basis of locality, geographic area or host plant. RIASSUNTO La tecnica AFLP è stata applicata a 109 colture della patovar pruni e 1 coltura della pv. juglandis della specie di Xanthomonas arboricola e a 5 ceppi di altrettante spe-cie del genere Xanthomonas. Gruppi di 12 e 41 colture della pv. pruni sono state isolate contemporaneamente da maculature di frutti in due pescheti in provincia di Verona (Italia); le altre colture della pv. pruni avevan