The strains of Pseudomonas savastanoi are responsible for the formation of tumors or excrescences in the aerial parts of woody plants, belong to the Pseudomonas syringaecomplex and are classified in the pathovars savastanoi (Psv, olive), nerii (Psn, oleander), retacarpa (Psr, Spanish broom) and fraxini (Psf, ash). The production of indole‐3‐acetic acid (IAA) in Psv and Psn is a factor of pathogenicity essential for the correct development of tumors in olive and oleander. In addition, IAA has been described as a signaling molecule capable of modifying gene expression of other virulence factors, such as the type III and type VI secretion systems. Most strains of P. savastanoi produce IAA from tryptophan through the indole‐3‐acetamide pathway. However, the iaaMHoperon is not present in Psf and it is not frequent in other pathovars of the P. syringae complex. Previously, our research group showed that a Psv ΔiaaMH mutant drastically reduces IAA levels and does not induce olive tumors. This mutant produces an IAA concentration in culture supernatant similar to produce by strains of Psf and other strains of P. syringae lacking these genes. These results suggest that the existence of an alternative route of IAA biosynthesis in Pseudomonas. In order to identify an alternative route, a comparative genomic analysis of P. savastanoi and other strains in the P. syringae complex was carried out. Currently, Psv mutants have been constructed in genes potentially involved in the biosynthesis of IAA. Additionally, a metabolic analysis of indolic compounds has been conducted to determine possible intermediates of this route. Finally, we carried out a comparative transcriptomic analysis (RNAseq) of the wild type Psv and its mutant Psv ΔiaaMHand was determined the impact of the addition of exogenous IAA to cultures of P. savastanoi. In summary, this work aims to identify new routes of IAA biosynthesis in P. savastanoi and to study regulatory roles of the phytohormone, IAA, on the expression of other virulence factors in Pseudomonas.Support or Funding InformationAGL2017‐82492‐C2‐1‐R (MINECO‐FEDER)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.