To combat infections, immune cells use NADPH oxidase to reduce O2 to oxygen free radical and then H2O2. Neutrophils and monocytes utilize myeloperoxidase to further combine H2O2 with Cl− to produce hypochlorite, which plays a role in destroying bacteria. Absence of NADPH oxidase will prevent the formation of reactive oxygen species and will result in chronic granulomatous disease.
Reactive oxygen species (ROS) in plants are important in various signaling cascades and are continuously produced by cells as byproducts of various metabolic pathways. They were mostly shown to be massively produced after the detection of PAMPs by cell-surface located receptors (e.g. FLS2 or EFR). The production of reactive oxygen species is mediated by the NADPH oxidase, and in plant immunity the subunits RbohD and RbohF have overlapping functions but are expressed in different tissues and in different levels. ROS production can be used as a readout for successful pathogen recognition via a luminol-peroxidase based assay.
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