Osbornellus horvathi potenziale vettore di fitoplasmi del gruppo 16SrIX.

At the present time seven subgroups have been described among phytoplasmas of group 16SrIX: -A, Pigeon Pea Witches-Broom (PPWB); -B and -D, ‘Candidatus Phytoplasma phoenicium’ (Almond witches broom, AlmWB); -C, Pichris echiodes yellows (PEY); -E, Juniper witches-broom; -F and -G, characterized in stone fruits in Lebanon. These phytoplasmas are associated with diseases affecting herbaceous and woody plants in different areas worldwide. In Italy they have been signalled in Dimorphoteca sinuata and Pichris echioides. Preliminary studies have shown the presence, just in Lebanon, of different leafhoppers genera as potential vectors of Almond witches-broom phytoplasma. During a survey for phytoplasma diseases in Sicily insects have been collected with sticky yellow traps or by insect net and tested by nested-PCR with universal primer pairs for detection of phytoplasmas. Among the trapped insects, the leafhopper Osbornellus horvathi resulted positive to phytoplasma. The four obtained sequences showed identity between 98,6% and 99% with 16SrDNA gene of the reference strain of ‘Ca. Phytoplasma phoenicium’ (AF515636). In virtual RFLP analysis with iPhyClassifier three of them (Osb1, Osb3, Osb4) shared a similarity coefficient (F) of 0,95 – 0,89 with the reference strain of subgroup16SrIX-E, while Osb2 shared a similarity coefficient (F) of 0,95 with the reference strain of subgroup16SrIX-C. To our knowledge this is the first report of O. horvathi as potential vector of phytoplasmas as well as the first report of potential vector of phytoplasmas of group 16SrIX.