Characterisation of emergent Tunisian isolates of <i>Pseudomonas syringae</i> pv. <i>tomato</i> the causal agent of bacterial speck disease of tomato

During 2017 spring, a phytosanitary issue has been noticed in tomato greenhouses in the Sahel of Tunisia and responsible bacterial isolates have been affiliated to Pseudomonas syringae pv. tomato (Pst). We aimed in this study to characterize Tunisian bacterial isolates of Pst and to test the response of seven tomato cultivars to this plant pathogenic bacterium. Five bacterial isolates were isolated from naturally infected tomato plants and were identified by biochemical and molecular methods. Tunisian Pst isolates exhibited similar LOPAT characteristics with reference Pst strains except for fluorescence in King B medium. Evaluation of susceptibility of seven of the mostly grown tomato cultivars showed that cv. Trujillo (registered in 2019 in Tunisia) behaved as resistant to this emergent bacterial disease. To our knowledge, this study reported for the first time a characterization of Tunisian isolates of Pst the causal agent of tomato bacterial speck disease.