Management of tobacco mosaic virus by some probiotic bacteria in tomato plant

Tobacco mosaic virus (TMV) is considered as a devastating virus which significantly reduces the tomato yield. This investigation aimed to find an efficient combination of plant probiotic bacteria to control TMV in tomato. Suspensions of Pseudomonas fluorescens, Pseudomonas putida, and Bacillus subtilis were prepared at the concentration of 108 colony forming unit per milliliter. Tomato seedlings, were treated with probiotic bacteria by adding 100 milliliters of suspension. Afterward, seedlings were inoculated with TMV and were inspected for six weeks. Subsequently, an indirect- ELISA test using TMV specific polyclonal antibody was used to compare the relative virus titer in the plants of each treatment. The experiment was conducted in a completely randomized design with nine treatments and six replicates, respectively. Results showed that the OD in the mixed bacterial treatment was lower (0.08) in comparison to the positive control (0.87) (p<0.05). Application of B. subtilis resulted in the higher OD (0.45) compared to the other treatments (p<0.05). Additionally, plant growth indicators including fresh and dry weight of root and above ground tissues of tomato as well as height of tomato plants and chlorophyl content were recorded. Application of plant probiotic bacteria significantly increased these indices in TMV-inoculated tomato plants compared to the control. The overall results showed that the mixture of three probiotic rhizobacteria had a synergistic effect, so that showed higher decrease in disease severity in comparison to the control.