Reactive oxygen species production in association with suberization: evidence for an NADPH‐dependent oxidase

In response to wounding, potato tubers generate reactive oxygen species (ROS) in association with suberization. Immediately following wounding, an initial burst of ROS occurs, reaching a maximum within 30 to 60 min. In addition to this initial oxidative burst, at least three other massive bursts occur at 42, 63 and 100 h post‐wounding. These latter bursts are associated with wound healing and are probably involved in the oxidative cross‐linking of suberin poly(phenolics). The source of ROS is likely to be a plasma membrane NADPH‐dependent oxidase immunorelated to the human phagocyte plasma membrane oxidase. The initial oxidative burst does not appear to be dependent on new protein synthesis, but the subsequent bursts are associated with an increase in oxidase protein components. Oxidase activity is enhanced in vitro by hydroxycinnamic acids and conjugates associated with the wound healing response in potato.