Evaluation of antagonistic effect of wheat rhizosphere Streptomyces on biocontrol of common root rot caused by Bipolaris sorokiniana

Common root and crown rot of wheat caused by Bipolaris sorokiniana is one of the most important diseases of wheat in the world. In this study, 60 isolates of Streptomyces were isolated from wheat rhizosphere and screened in laboratory condition using dual culture. UTS22, UTS3 and UTS4 isolates showed maximum inhibition with 46.6, 45.6 and 42% respectively. Most of the isolates had positive reaction for physiological and enzymatic activities such as colonization, nitrogen fixation, phosphate solubility, protease and chitinase. UTS3, UTS18 and UTS4 isolates showed the highest inhibition levels of pathogenic mycelial growth by producing metabolites with 67.96, 61.3 and 54.63% respectively. Greenhouse studies carried out in a completely randomized design with wheat seed coat method with 108 CFU/ml concentrations of supernatant isolates. Based on the results, the UTS22 isolate showed the highest disease control with 55.6% and also wheat growth indices increased significantly compared to healthy control treatment. Molecular identification based on the sequence of 16S showed, the UTS22 isolate belongs to Streptomyces fulvissimus. UTS22 is introduced as a superior isolate in biological control of B. sorokiniana.