Phytoplasmas are bacteria, which belong to the class Mollicutes. In nature they inhabit insects and phloem of plants. They are plant pathogens transmitted and disseminated by sap feeding insects. Candidatus Phytoplasma prunorum is a quarantine plant pathogen bacteria belonging to the apple proliferation group. It is the causative agent of leptonecrosis of stone fruits. Because of its negative impact on fruit yield, it presents a major problem for fruit growers. Consequently, this results in significant economic damage. The main transmission vector of Ca. P. prunorum is Cacopsylla pruni (Scopoli). Using molecular methods we analyzed 20 samples of apricots and peaches, infected with the phytoplasma and classified them into one of the genetic subgroups. All the samples were collected in Slovenia. On the basis of the gene aceF we distinguished four genotypes, on the basis of gene secY two genotypes, on the basis of gene pnp one, and on the basis of gene imp five different genotypes. Additionally, we made a multilocus sequence analysis and found seven different haplotypes of Ca. P. prunorum. Based on the results we can conclude that the genetic diversity of Ca. P. prunorum in Slovenia is high. Additionally, we analyzed 42 DNA samples, that were extracted from C. pruni and demonstrated that all of the samples from the C. pruni complex belong to the genetic group B.
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