Determination of copper resistance of bacterial canker caused by Pseudomonas syringae pathovars izolated from stone fruit trees

To control Bacterial canker, one of the most important diseases on stone-fruit trees in the world, copper-based pesticides has been used for a long time. However, the pathogens have developed resistance to copper. The aim of this study was to detect the copper tolerance rates and their related tolerance mechanisms in strains of Pseudomonas syringae pv. syringae and morsprunorum isolated from Lake Van Basin where the usage of copper pesticides is low and Ege region where that usage is high In-vitro and molecularly. In-vitro works included growing the isolates on Methanol-glutamine agar (MGY) medium with different copper sulfate concentrations along with 4 commercial copper-based pesticide and Minimum inhibition concentrating (MIC) was showed. The existence of the related resistance genes copA and cusA in the tolerance strains were studied by PCR and after the sequence analysis was created, the relationship between the isolation areas and the isolates was studied by creating a phylogenetic tree. The resistance level was different according to the isolates and the used copper formulation. Between the pesticides Bordeaux mixture with Mancozeb was the best but when looking at only copper effect, copper oxychloride showed the best results between the pesticide. The maximum MIC value in all isolates was 2 mM and 79 % of it was 1 mM and below. The gene copA was found in only 4 isolates and 3 of them where isolated from İzmir. Althogh, there was no differences in the copA gene sequences between the pathovars, the isolates were separated into two groups. cusA gene was not found in any isolate. It was shown that the different resistant rates in the isolates with no resistance genes could be related to the strains ability to produce Chalkophores.