Characterization on six genes of ‘Candidatus Phytoplasma asteris’-related phytoplasmas infecting cyclamen.

The presence of phytoplasmas in potted cyclamen plants showing malformations, phyllody and virescence of the flowers was detected by PCR assays with primers amplifying phytoplasma 16Sr, GroEL, secY, rp, tuf and amp genes. RFLP analyses allowed to identify the detected phytoplasmas in the aster yellows subgroup 16SrI-B. These phytoplasmas were identical to each other and to reference strains belonging to 16SrI-B subgroups on all studied genes except amp gene, and were further classified as rpI-B, SecYI-B and GroELIIII groups. This multigene characterization of a ‘Candidatus Phytoplasma asteris’-related strain infecting cyclamen in Italy allows its distinction from reference strains by RFLP analyses of the amp gene.