S14 - Session O5 - The sanitary crisis caused by Xylella fastidiosa, a plant pathogenic bacterium recently discovered in Europe with a focus on the situation in France

Authors: Marie-Agnès Jacques *, Enora Dupas, Sophie Cesbron

Emergences of plant pathogenic bacteria have a resounding effect when they are responsible for diseases with major socio-economic consequences. This was the case for the rapid decline of olive trees discovered in 2013 in Puglia, Italy. This disease is caused by Xylella fastidiosa, a proteobacterium of American origin. The epidemic nature of this disease, the emblematic nature of its main hosts in the Mediterranean area and the lack of control methods quickly led other Mediterranean countries to increase the surveillance effort on their territories. Thus, a large diversity of strains belonging to this bacterial species has been identified in many plant species in other European countries, such as France, Spain and Portugal. Our studies to uncover the most probable scenario having led to X. fastidiosa introduction in France will be presented. The description of the strains, their typing, and the analysis of their genome now indicate that multiple introductions of various strains have taken place in the past. The divergence time between these strains and their American relatives suggests ancient introductions that remained unnoticed, probably because of the unspecific symptoms affecting diverse ornamental species.