نبذة مختصرة : Background and Objectives Bacterial canker of tomato caused by Clavibacter michiganensis subsp. michiganensis, Cmm, is one of the limiting diseases of tomato cultivation. Because of the chemical control problems, biological control methods have been used to control this disease in recent investigation. Basil (Ocimum basilicum L.) is an annual herbaceous plant from the Lamiaceae family, and various endophytic bacteria have been reported from this plant. Also, many studies have shown that endophytic bacteria can stimulate growth and control many plant diseases. Therefore, in recent research, it was tried for the first time to test endophytic bacteria isolated from basil plants against tomato bacterial canker. Materials and Methods In this research, 16 endophytic bacteria were isolated from basil. They were tested for their antibacterial properties against tomato bacterial canker in laboratory conditions using chloroform vapor. Also, the effect of these bacteria on increasing total phenol and growth factors, including fresh weight, dry weight, and seedling height, were investigated. In the next step, the best bacteria in terms of growth factors were used to control bacterial canker, on tomato seedlings, under greenhouse conditions. Next, the physiological changes related to total phenol, catalase and peroxidase were investigated. Finally, molecular identification was done by PCR using universal 16SrRNA genespecific primers, 27f and 1492r, DNA sequencing and BlastN in NCBI Genebank. Results ReA1 isolate was detected as Enterobacter sp. by DNA sequencing results. None of the endophytic bacteria showed antibacterial properties against bacterial canker under laboratory conditions. ReA1 isolate showed the highest growth stimulation and total phenol increase compared to other bacteria; therefore, it was used against tomato bacterial canker and reduced the disease by nearly fifty percent. Also, the growth factors were increased compared to the infected and healthy controls after inoculation with ReA1. In addition, the amount of peroxidase, catalase, and total phenol increased in plants treated with ReA1 isolate compared to the control. So that the amount of total phenol, peroxidase, and catalase, respectively, from the highest to the lowest, was related to the application of ReA1 and Cmm, ReA1 alone, Cmm alone, and the control without bacteria. Discussion Recent research showed that Enterobacter sp. strain ReA1 isolated from a plant belonging to the Lamiaceae family (basil) was tested on tomato plants from the Solanaceae family, which was able to reduce tomato bacterial canker disease without a direct antibacterial effect. The possible main effects of this bacterium are related to the phenomenon of induced resistance in the plant and the increase of defensive and antimicrobial compounds in the plant. This control effect on the different plant species belonging to Solanaceae probably allows using this bacterium as a biological control agent in many plants and against a wide range of plant diseases. It also stimulates plant growth, making the simultaneous use of this bacterium as a fertilizer and biocontrol agent possible. [ABSTRACT FROM AUTHOR]
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