Late blight caused by the fungus Phytophthora infestans, is one of the most important diseases of potato (Solanum tuberosum L.) crop worldwide. However, in spite of its importance, understanding of the pathosystems mediating potato infection by this fungus is still limited. Therefore, to better understand the defense responses initiated by potato resistant plants challenged with P. infestans, expression of six well known defense-related genes were monitored at early four-time points of infection. Time-course experiments revealed notable differences in gene expression patterns during potato-pathogen interaction as compared to the non-infected control. It is noteworthy that both PR3 and StSYR1 have higher constitutive expressions with 6.1 and 8.1 folds, respectively, at 48 and 72 hours post inoculation (hpi) period. It was clear that their expressions were higher at the necrotrophic stage compared with the biotrophic one. According to findings, our data can provide an insight into the signaling pathways that accounts for conventional gene expression changes elicited during potato-P. infestans interactions.