Induction of Systemic Resistance in Tomato Plants Against Tomato yellow leaf curl virus in Protected Cultivation Using a Local Bacterial Isolate of Bacillus subtilis

Abstract

This study was conducted at the Agricultural Scientific Research Center in Lattakia Governorate in a plastic house during the 2020/2021 growing season to evaluate the efficiency of the native bacterial isolate B.Ra.217 of Bacillus subtilis, in reducing infection of tomato plants with Tomato yellow leaf curl virus (TYLCV), by treating tomato seeds and later watering the seedlings with a suspension of the tested bacteria at a concentration of 1x109/ml, and then measuring incidence (%) and severity of virus infection, and estimating peroxidase enzyme activity. The results showed that 30 days after inoculation with tomato leaf curl virus, a decrease in virus infection rate and severity in virus-infected and bacteria-treated plants compared with virus-infected and untreated control plants was observed. The reduction in disease incidence and severity of infection reached 26.67% and 34.28%, respectively, with significant differences between the treatments. In addition, the activity of peroxidase enzyme 7 days after infection with the virus showed an increase in plants treated with bacteria only (0.1342 μmol/mg) and those treated with bacteria and virus-infected (0.0913 μmol/mg), compared with the healthy control plants (0.0958 μmol/mg), and virus-infected and untreated with bacteria (0.0570 μmol/mg). The results also showed 15 days after infection that the enzyme activity was higher in plants treated with bacteria only (0.1592 μmol/mg) compared with the healthy control (0.1415 μmol/mg) with significant differences, and also the differences were significant with the untreated infected plants (0.1002 μmol/mg), and with inoculated and treated plants (0.1372 μmol/mg). Thus, this bacterial isolate may have an important applied role in enhancing tomato plant resistance to the virus and consequently reducing its damage.