A Molecular survey to identify phytoplasmas associated with apple trees showing different diseases symptoms

Apple trees showing a diverse range of symptoms from the Czech Republic and the UK were tested several times during the year to monitor and identify phytoplasmas. The trees were examined by nested PCR using broad spectrum or group specific primers to amplify phytoplasma 16SrDNA, or 16SrDNA plus spacer region. The identity of PCR products was confirmed by RFLP analyses. Several cultivars from the Czech Republic showing symptoms of rubbery wood, apple proliferation, or leaf deformation and reddening were examined, together with plants of the cv Lord Lambourne from the UK showing rubbery wood symptoms. Of the plants tested only a few were positive in nested PCR. The results suggest that apple trees can harbour phytoplasmas from groups 16SrI-B, 16SrI-C, 16SrX-A and 16SrXII-A. It is also apparent that phytoplasmas belonging to 16SrX-A group, typically associated with apple proliferation symptoms, could also occur in symptomless apple trees or in trees with symptoms other than typical apple proliferation.