Amplification of fragments containing phytoplasma groEL gene sequence with a newly designed nested PCR system allowed to specifically detect the presence of 'Candidatus Phytoplasma asteris' in reference strains as well as in samples field collected and maintained as dry/freeze dried nucleic acids. After RFLP analyses it was possible to confirm further finer differentiation among strains enclosed in subgroup 16SrI-B by previous ribosomal gene classification.
