Local distribution of ‘Candidatus Phytoplasma mali’ genetic variants in South Tyrol (Italy) based on a MLST study

Apple proliferation is one of the economically most important apple diseases in Europe and infection rates are increasing over the last years in many apple growing areas. ‘Candidatus Phytoplasma mali’, the agent associated with the disease, is transmitted by two psyllid species, Cacopsylla melanoneura and C. picta. A multilocus sequence typing analysis was performed to determine genetic variability of ‘Ca. P. mali’ in infected trees and insect vectors. Two major genetic clusters were identified and occurrence of sequence variants is different in the geographic areas of South Tyrol (North Italy).