Plant growth-promoting rhizobacteria (PGPR) exert beneficial effects on plant growth and immune system. In the MSc thesis, we monitored the response of potato plants post Bacillus subtilis root colonization on transcriptomic level. For this purpose, we selected two Bacillus subtilis strains, PS-216 and PS-218, and two potato genotypes Rywal and Desiree. We examined root colonization by B. subtilis strains as well as response in roots and leaves at different time points. The onset of PS-218 biofilm formation on the roots of Rywal genotype was observed after 30-minutes incubation period of plants in precultivated bacterial culture, after two hours, biofilm was observed along entire root surface. When the bacterial culture was not precultivated, PS-216 biofilm formation on roots of both genotypes was observed after 6-hours incubation period, and PS-218 biofilm after 5-hours of incubation. Also at all next examined time points, biofilm formation on roots was confirmed. We confirmed the response of potato plants post B. subtilis root treatment. We detected the altered expression of selected genes in leaves and roots of plants inoculated with B. subtilis at all analysed time points. We detected effect on gene expression in roots early at the time of biofilm formation, response was most pronounced after 2-hours incubation period. Response to B. subtilis in leaves was more pronounced after overnight incubation. PTI5 and 13LOX genes were identified as maker genes of potato response to B. subtilis, as their expression was significantly induced in leaves and roots of potato plants post B. subtilis inoculation.