Sumoylation in Arabidopsis: stress response, signaling & evolution

Plants constantly face changing environments that can be hostile. One strategy to adapt to such (a)biotic challenges consists of transiently modulating protein activity by attachment of small molecules to proteins. The reversible attachment of these molecules is referred to as post-translation modifications (PTMs). The nature of these small molecules varies, ranging from small chemical groups (like in acetylation or phosphorylation) to peptides (like in ubiquitination). In the last three decades, a group of PTMs that shares its protein fold with ubiquitin and that are conjugated in a similar manner as ubiquitin to target proteins, has been discovered. One well-established and essential member of these so-called Ubiquitin-like modifiers is Small Ubiquitin-like Modifier (SUMO). Using the model plant Arabidopsis thaliana, this thesis investigates the role of SUMO conjugation in plant defense signaling and in acclimation to elevated temperatures. In addition, this thesis explores the evolutionary mechanisms that shaped the SUMO gene family in this model plant.