Effects of Temperature on Resistance to Streptomycin in Xanthomonas arboricola pv. pruni

Xanthomonas arboricola pv. pruni (Xap) causes the shot hole disease of stone fruits and almonds. This bacterium is a damaging, widespread pathogen distributed across the major stone fruit producing regions of the world. To control shot hole disease, antibiotics such as streptomycin are mainly used. However, as concerns about antibiotic resistance increase, many restrictions are placed on the use of antibiotics. Additionally, it has been reported that the rise in temperature due to climate change affects disease occurrence and ecology. Therefore, in this study, we determined the minimum inhibitory concentration (MIC) of streptomycin for Xap at an optimal growth temperature of 28°C and investigated the changes in MIC and the occurrence frequency of resistant bacteria at 10°C, 25°C and 30°C. The results of this study showed that the MIC was 30 µg/ml at 28°C. In addition, when the change in streptomycin resistance concentration due to temperature was confirmed, we found that the resistance concentration decreased to 10 µg/ml at 30°C. When the occurrence of resistance according to concentration and temperature conditions was investigated, the occurrence frequency of resistant strains was found to be the highest at 50 µg/ml. In the case of temperature, the occurrence frequency of resistant strains was confirmed to be high at 30°C. These results provide basic data for further reducing the problem of antibiotic resistance by suggesting the possibility of changes in the occurrence of streptomycin-resistant strains depending on the antibiotic treatment environment.