Host-plant range of different Xylella fastidiosa subspecies in experimental tests

Since the first detection of Xf in Europe in 2013, various strains ofat least four subspecies were reported. De Donno strain from thesubsp. pauca infects mainly olive trees, but was recovered frommore than 20 other plant species. Strains from the subspeciesmultiplex, sandyi, fastidiosa and pauca have been identified inSpain, in France and in the north of Italy infecting altogether morethan 60 plant species. Large overlaps in host range of the varioussubspecies were noticed. However, these host lists came from analysis of naturally occurring infections that depends largely onuncontrolled factors such as host availability where the strain ispresent and presence of insect vectors attracted by these plants. Thepotential host range of the different strains circulating in Europe ordreaded strains remain poorly understood. We tested thepathogenicity of several strains belonging to different subspecies(fastidiosa, pauca, multiplex and sandyi) on a large range of plants ofinterest for French horticulture such as citrus, grapevine, olive trees,apple, pear, plum and apricot trees.