Microsatellite profile of Plasmopara viticola isolates collected in Italy

Downy mildew, caused by the oomycete Plasmopara viticola, is one of the
most serious threat to viticulture. P. viticola is native to North America
and causes the most severe damages to the Eurasian grapevine, Vitis
vinifera. In this work, we investigated the genetic structure of the
pathogen in Italy by collecting 96 P. viticola strains in twelve different
regions. Based on microsatellite characterization (19 microsatellites), we
confirmed that the Italian population of P. viticola is composed of two
separate subpopulations and determined that these two cluster differ for
geographic and climatic conditions. These populations could have been
originated from the introduction of two separate populations or, more
likely, from the evolution of the original population that reached Europe
at the end of the XIX century. The pathogen showed a great evolutionary
potential, as highlighted by the regular occurrence of sexual
reproduction, panmictic structure within cluster and absence of clones.
These results confirm that the P. viticola has a strong potential for
adaptation and suggest the integration of all the tools (genetic,
agronomic and chemical) for achieving a proper disease management.