Microsatellite profile of Plasmopara viticola isolates collected in Italy

<p class="MsoNormal"><span>Downy mildew, caused by the oomycete <em>Plasmopara viticola</em>, is one of the most serious threat to viticulture. <em>P. viticola </em>is native to North America and causes the most severe damages to the Eurasian grapevine, <em>Vitis vinifera. </em>In this work, we investigated the genetic structure of the pathogen in Italy by collecting 96 <em>P. viticola </em>strains in twelve different regions. Based on microsatellite characterization (19 microsatellites), we confirmed that the Italian population of <em>P. viticola</em> 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 <em>P. viticola </em>has a strong potential for adaptation and suggest the integration of all the tools (genetic, agronomic and chemical) for achieving a proper disease management.</span></p>