During 2010-2013, samples from 267 apple trees growing in six regions of Poland were tested for phy-
toplasma presence. ‘Candidatus Phytoplasma mali’ was detected in 17 samples from phloem tissue of apple shoots
showing typical apple proliferation symptoms. Molecular characterization of these strains was conducted using
PCR-RFLP and sequence analyses of three regions: ribosomal DNA, ribosomal protein and non-ribosomal DNA
fragment including nitroreductase and rhodanese-like protein genes. Fragments of 16S rDNA plus 16S-23S spacer
region from the ‘Ca. P. mali’ strains showed two restriction profiles: P-I and P-II when digested with HpaII enzyme.
Moreover, based on results of nitroreductase and rhodanese-like protein genes, these phytoplasmas were grouped
into two subtypes: AP-15 and AT-1. The majority of the ‘Ca. P. mali’ strains was classified to the AP-15 subtype.
Two strains were grouped to the AT-1 subtype and another showed both AP-15 and AT-1 profiles. Based on results
of analysis of rpl22 and rps3 ribosomal protein genes, most of the ‘Ca. P. mali’ strains were identified as belonging
to rpX-A. Only one strain was affiliated to rpX-B subgroup
