Figure 2.

Overview of ROS Perception Mechanisms.

(A) Oxidative posttranslational modifications of cysteine and methionine residues. Alkalization of the apoplast is expected to increase the availability of thiolate anions for reaction with H₂O₂. The oxidation of methionine residues is pH independent within the apoplastic pH range.

(B) RLK-assisted ROS perception mechanisms. Asterisks indicate pH-dependent reactions, assuming that the oxidized amino acid residues are cysteines. See the main text for a detailed description. Prx, peroxiredoxin.