Molecular identification of phytoplasmas from virescent ranunculus plants and from leafhoppers in southern Italian crops.

During late 2005, a severe phytoplasma-like disease was observed in the Persian buttercup hybrid cv. Pauline in two commercial greenhouses in Southern Italy. Early symptoms consisted of growth abnormalities and shoot proliferation followed by decline, whereas at the flowering stage virescence and phyllody prevailed. The presence in diseased samples of a Candidatus Phytoplasma asteris-related strain, belonging to the 16SrI-B subgroup was demonstrated by PCR-RFLP and phylogenetic analysis. The same phytoplasma was also identified in two batches of ten individuals of Empoasca decipens collected during field surveys, but a Ca. P. aurantifolia- related strain was detected in a third batch of the same leafhopper species. Possible infection pathways for the disease in ranuculus and the risk linked to the new report of a 16SrII-B phytoplasma in Italy are discussed.