<jats:p>The root system of the plant is essential for taking up water and nutrients, serves as an anchor and is the organ where plant-microorganism interaction takes place. When the Plant Growth Promoting Rhizobacteria (PGPR) Azospirillum brasilense Sp245 colonizes the root of the plants, it halts the growth of the primary root and stimulates the development of the lateral roots and root hairs which support vegetative, green biomass. Target of Rapamycin (TOR) is a highly conserved protein in all eukaryotes, and it controls anabolic processes, such as cell cycle, ribosome biogenesis, protein synthesis, cell wall changes and photosynthesis among others. TOR in plants forms part of the TORC1 complex, which when is activated by auxins and light, activates anabolic processes and represses autophagy. TOR regulates the growth of the primary root of Arabidopsis through cell proliferation and elongation. In the present investigation, the participation of TOR during the Arabidopsis-Azospirillum interaction was determined using two approaches, a pharmacology and other genetic. The results showed that TOR is involved in the development of the lateral roots of A. thaliana seedlings inoculated with A. brasilense.</jats:p>