My work is focused on the effector repertoire in the Pseudomonas syringae species complex, a major plant pathogen infecting a wide range of plant species, including those of high agricultural relevance. Type III Secretion System effectors (T3SEs) are injected into plant cells by the bacteria in order to manipulate host immunity and metabolism to the pathogen’s benefit. The precise repertoire ofT3SEs varies dramatically across the species complex and has a complicated relationship with pathogenicity. Using in silico tools, I investigate the distribution, phylogeny and protein structure of T3SEs identified in our Tübingen isolate collection of 1524 genomes.