The goal of this project is to complement transcriptomic data of the oxidative stress response with proteomic data. Catalase deficient Arabidopsis are the experimental model system to study the effect of enhanced endogenous H2O2 levels. Besides defining the differences in protein abundances between WT and mutants using shotgun proteomics, both tyrosine nitration and methionine oxidation will be assessed by use of the COFRADIC technology.