The current study was performed to evaluate the potential of two plant extracts (from Nigella sativa L. seeds and Clerodendrum inerme L. leaves) and salicylic acid to induce systemic resistance (ISR) against Potato virus Y (PVY) in potato plants. Ultrastructure investigations using the transmission electron microscope (TEM) exhibited Pinwheels and Ga-Golgi apparatus in the infected plants. Flexuous filaments particles (with a model length of 730×13 nm) were observed in the infected sap using TEM investigation. RT-PCR technique revealed a band- sized at 610 bp in the infected samples with PVY. The infection with PVY was confirmed morphologically and histologically. The most effective treatment for induction of ISR was Nigella sativa L., since the highest reduction of virus infection and the lowest inhibition rate (34.7 and 61.7, respectively), were recorded in plants treated with this plant extract and salicylic acid. Peroxidase (POD) activities were 59.7and 37.7 and polyphenol oxidase (PPO) activities were 23.7and 21.0  after 1- and 2-weeks of Nigella sativa L. treatment, respectively.On the other hand, salicylic acid had the lowest effect on decreasing PVY infection rate and virus inhibition, resulting in of ISR in potato plants. Taken together, the extracts of Nigella sativa and Clerodendrum inerme as well as salicylic acid could be used to control PVY infection. A further study is needed to evaluate these materials under field conditions.