Strain P. fluorescens was supplied by College of Plant Protection, Shenyang Agricultural University, China. The strain was identified and reported as a potent antagonistic agent against TMV (Shen et al.,2017). Submerged fermentation broth was produced and centrifuged it. Broth was used for antimicrobial activity. Make 30% dilution of the active fraction with distilled water. Bacillus subtilis was used as a test pathogen. Silver nitrate and extracted broth from P. fluorescens strain were mixed. The reaction was set up by a mix of 90 ml of AgNO3 with 10 ml of bioactive substance at 80 c by keeping at 5 pH and stirring it for 2 h and then put it over 1 day. The upper layer was removed by centrifuge to get rid of the impurities. Separated substance further dried at 80 c for 12 h and then crushed into a fine powder, and finally, at 700 c for 3 h calcinated to remove all the impurities (EL-Moslamy Shahira, 2018). X-ray diffractometer was used to calculate the diameter of nanoparticles. SEM analysis was done to observe the shape of the synthesized NPS. TMV obtained from the Lab of Shenyang Agricultural University, Shenyang, China. The viral inoculum was maintained on infected tobacco plants. Humidity and temperature were maintained. Nicotiana glutinosa was transplanted into a small pot in the greenhouse after seedling cultivation, and the same growth of tobacco seedlings was selected for reserve in 5–6 leaf stage.
Silver nanoparticles (AgNPs) (100 μl) treatment was given 24 h before TMV inoculation on the leaf.
Mix the TMV supernatant with 100 μl AgNPs for 10 min and rub the leaf with the mixture
Inoculate the plant leaf with TMV and after 24 h treated with AgNPs
Five seedlings per treatment were inoculated with 3 leaves per seedling. After the onset, the number of the lesions was investigated and the inhibition rate of the lesions was calculated. To observe the effects of AgNPs and TMV, supernatant was sprayed. For control, TMV was mixed with a 1:1 ratio with distilled water. After 36 h, it was photographed. Later, the same plant sample was observed by using the transmission electron microscope (TEM), to determine the effects of nanoparticle on the morphology of TMV.