Introducing of Bacillus subtilis UTBMS7 as a probiotic bacteria against on wheat Evaluation of the potential of some bacterial isolates for biological control of angular leaf spot disease of cucumber

Plant growth-promoting rhizobacteria have great potential for increasing plant biomass and controlling plant diseases. Therefore PGPRs can be good substitute for the use of pesticides and chemical fertilizers in agriculture. For evaluation of the effects of antagonistic activities of several PGPRs against Pseudomonas syringae pv. lachrymans the causal agent of cucumber angular leaf spot disease in laboratory and greenhouse Conditions. Several bacteria isolated from different cucumber rhizosphere soil in Kerman province and a number of bacterial strains in the collection of Vali-e-Asr University of Rafsanjan were used. After in vitro screening, four isolates with ability of growth inhibitory effect were selected for further studies in vitro and in planta. Antibacterial activity characteristics of biocontrol agents such as production of secondary metabolites and some of their plant growth promoting traits were evaluated in vitro. During in planta study, the ability of bacterial strains to prevent the development of symptoms using the area under disease progress curve (AUDPC) and increasing the biomass of cucumber plant were evaluated. Greenhouse study showed that Pseudomonas fluorescens VRPF 54 strain have high biocontrol efficacy. During in planta study, this strain, both alone and in the interaction plant-pathogen in comparison with the control plant, significantly increased biomass and controlled cucumber leaf spot disease. After selection of this strain, some its antagonistic activities, biochemical properties and molecular identification were screened in vitro. Also, the assay of antioxidant enzymes activity such as peroxidase, guaiacol peroxidase, phenylalanine ammonia lyase, polyphenol oxidase and total phenol content were considerably increased.