Possibilities of using bacteriophages for biological control of tomato bacterial speck disease (Pseudomonas syringae pv. tomato)

Tomato (Solanum lycopersicum L.), is the most widely grown vegetable crop throught the world. The bacterium known as Pseudomonas syringae pv. tomato (Pst), causes bacterial speck disease on tomatoes. Alternative control strategies are studied for that disease management. The use of the bacteriophages is one of those strategies. Bacteriophages are natural enemies of bacteria and extremely specific to their targeted hosts without affecting any other bacteria. In this study, isolation of Pseudomonas syringae pv. tomato-lysing bacteriophages and the possibility of using these bacteriophages as biological control agents were investigated. Therefore, samples of tomato plants with typical symptoms of bacterial speck disease were collected from 17 tomato fields, 12 greenhouses and four nurseries in Adana and Mersin provinces. The bacteriophages were isolated from the sample using NYGA medium. As a result, after 36 hours of incubation, the plaques (inhibition zones) were observed and 47 bacteriophages were purified. Among the obtained bacteriophages, the CMN 33 isolate was completely (100 %) suppressed the growth of pathogen and increased the germination rate by %14.6, whereas the CMN 34 isolate was suppressed the pathogen by 65.8 % and increased the germination rate by 21.6 %. It was determined that these bacteriophages (CMN 33 and CMN 34) were specific to Pseudomonas syringae pv. tomato and had no effect on the saprophytic bacterial flora on tomatoes. To our knowledge, this is the first study to investigate the possibility of using bacteriophages for biological control of plant diseases in Turkey.