Detection and characterization of Plum Pox Virus isolates in Lombardia and Veneto regions (Italy)

Plum pox virus (PPV) was initially found in Italy in 1974 in Alto Adige region. After that it was detected in almost all Italian regions. During the last decade stone fruits orchards in Northern Italy have been affected by serious outbreaks of sharka disease mainly due to PPV-M isolates. From 2001, orchards of different stone fruit species and cultivars (above all peach, apricot and plum) have been surveyed in Lombardia and Veneto regions and different samples have been collected. They have been characterized by indexing on herbaceous and woody hosts and by ELISA using monoclonal antibodies specific to the four strains: Mab4DG5 (D), MabAC (C), MabEA24 (EA) and MabAL (M), and the virus specific: Mab5B. Moreover, they have been analyzed by RT-PCR, followed by AluI and RsaI RFLP analysis. PPV isolates considered to be the most interesting from the biological point of view have been selected to amplify, clone and sequence part of the NIb and the coat protein coding regions. Results clearly show that the most widely spread PPV isolates belong to the M group and, in particular, they are very similar to the Hungarian SK68 isolate.