Figure 1.

Generation sites of reactive oxygen species (ROS) and redox biology. ROS are produced by respiratory burst oxidase homologs (RBOHs), mitochondria, chloroplasts, peroxisomes, and cell wall-resident peroxidases (PER). Subsequent H₂O₂ accumulation may oxidize cysteine residues in proteins, affect their redox states and functions, and regulate related signaling pathways. Excessive ROS may lead to oxidative stress, which may cause lipid oxidation, DNA damage, protein carbonylation, and injuries to other cellular components.