Identification of Bacterial Isolates with Antagonistic Activity Against Pseudomonas syringae pv. atrofaciens, the Causal Agent of Basal Glume Rot in Wheat, and Their Plant Growth-Promoting Traits

In this study, bacterial isolates exhibiting antagonistic properties against the seed-borne pathogen Pseudomonas syringae pv. Atrofaciens in wheat were investigated. Among a total of 298 bacterial isolates obtained from wheat seed samples, 19 candidate antagonistic isolates were selected based on their pectolytic activity and hypersensitivity test results. Molecular identification revealed that these isolates belonged to the genera Pseudomonas, Bacillus, Paenibacillus, Citrobacter, and Staphylococcus. In vitro antagonistic tests showed that Pseudomonas japonica isolates W57.4 and W57.5, along with Paenibacillus polymyxa isolate W58.1, exhibited the highest inhibitory effects. These isolates also demonstrated multiple plant growth-promoting traits such as protease enzyme production, phosphate solubilization, siderophore synthesis, ammonia production, and indole-3-acetic acid (IAA) production. Notably, P. japonica isolates (W57.4, W57.5) exhibited strong siderophore production and phosphate solubilization, while P. Polymyxa (W58.1) showed high protease activity. These multifunctional traits indicate the potential of these isolates to be used as biological control agents against seed-borne pathogens. As the first study in Türkiye focusing on the biological control of seed-borne bacterial pathogens causing basal glume rot in wheat, this research provides a significant contribution to the development of environmentally friendly and effective alternative management strategies.