We will study E3 Ubiquitin ligases from the model plant Arabidopsis thaliana that are putatively involved in jasmonate signalling. We aim to (1) identify their actual substrates, (2) acquire mechanistic insight in how they are regulated themselves,and interact and ubiquitinate these targets, and (3) phenotypically characterise Arabidopsis plants with altered expression in these E3 Ub ligases to establish their precise role at the whole plant level.