SUMO news: Antagonistic crosstalk among Arabidopsis SUMO isoforms in immune balances/trigger

Plants have been endowed with the ability to tolerate diverse external stress. Several proteins that have been discovered to play a critical part in this adaptation respond quickly to the environmental cues. Post-translational modifications on proteins provide capacity to regulate their functions/fates. This study investigated SUMOylation, the covalent attachment of Small Ubiquitin like modifiers (SUMO) to the unique lysine residue on a target protein. We demonstrated that different Arabidopsis thaliana isoforms of SUMOs modify core immune-related proteins such as SRFR1 and EDS1, altering the plant’s response to the bacterial pathogen Pseudomonas syringae. We observed a tug of war between the two distinct SUMOs, SUMO1 and SUMO3, for functional modification of the above immune players. SUMO1 puts a check on mis-priming of defence activation whereas SUMO3 support defense responses. Under pathogen attack, both SUMO isoforms coordinate to achieve appropriate response without fitness costs to the host plant. Front. Cell Dev. Biol., 30 September 2021 https://doi.org/10.3389/fcell.2021.680760