Genetic diversity and a long evolutionary history of plum pox virus strain rec in Turkey

Plum pox virus strain Recombinant (PPV-Rec) is hypothetically considered as homologous recombinant between strains PPV-M and PPV-D. The nucleotide position 8450 up to end of genome is considered to come from PPV-M, and the remaining major genomic part is PPV-D-derived. It is regarded as third major PPV strain due to its wide distribution and prevalence in Europe. However, among over a thousand PPV isolates genetically identified in Turkey, only 10 of them (<1%) were characterized as PPV-Rec. The nearly complete genome of eight of the PPV-Rec isolates from European part of Turkey were obtained and analyzed together with PPV-Rec isolates of other countries. All major genomic features were conserved among Turkish PPV-Rec isolates. The genetic diversity of PPV-Rec isolates in Turkey (n = 8, 0.015 +/- 0.001%) was found to be comparable to that observed for the isolates from eight countries (n = 10, 0.014 +/- 0.001%). Particularly, genetic diversity of the minor recombinant fragment for Turkish PPV-Rec isolates was apparently higher (0.016 +/- 0.001%) than the value for the 10 isolates from eight countries (0.011 +/- 0.001%). The high genetic diversity was also demonstrated by high phylogenetic variation in Turkish isolates, indicating a long evolutionary history of PPV-Rec isolates in Turkey. After including Turkish isolates in the recombination analysis, the major putative recombination event of PPV-Rec isolates with a breakpoint around position 8450 was identified again, however the other recently reported putative recombination events were not supported in this study by the algorithms implemented in the RDP software.