Tomato Plant Response to Induction of Resistance to R. solani Using Gamma irradiated Bacterial Biocontrol mutants

The aim of this study was to evaluate the tomato plant induced resistance to Rhizoctonia solani using bio-control bacteria of Bacillus subtilis. Three bacterial isolates including B1 (un-irradiated B. subtilis), B600 and B419 (gamma-irradiated B. subtilis mutants) were used in this study. Results showed the highest activity of polyphenol oxidase enzyme in plant infected with pathogen. This increase in polyphenol oxidase activity was due to the response of the plant to the pathogen, which led to an increase in the activity of the enzyme, indicating an increase in oxidation in the plant. All treatments except B1 + Pathogen showed lower levels of peroxidase enzyme activity than the pathogen infected plant. All the plants treated with bio-control bacterial showed a significant increase in chlorophyll a compared to control. In plants treated with bio-control agents, the highest level of chlorophyll b in B600 + Pathogen and B1 + Pathogen were measured. The highest Disease Incidence percentage (DI%) was observed in plant pathogen (negative control) and the lowest DI was observed in plants treated with B419 + Pathogen. In plants treated with bio-control agent, the highest amount of chlorophyll b was calculated in B1 + Pathogen and B600 + Pathogen treatments. The highest percentage of Disease Incidence percentage (DI%) was observed in the pathogen-infected plant and the lowest in the B419 + Pathogen treatment. The treatment with bio-control agent increased tomato yield and even the highest yield was recorded in the B419 + Pathogen treatment.