ABSTRACT
The nature, occurrence, and role of superoxide dismutase (SOD) in animal and plant cells, as well as the biochemical implication of oxygen radical production and reactivity, have been well studied. Exposure of plant tissues to ultraviolet (UV) light is also assumed to generate superoxide immediately after exposure. The enhanced chemiluminescence was inhibited by scavengers of superoxide and H2O2, such as SOD and catalase, and also by the peroxidase inhibitors, salycylhydroxamic acid and cyanide. The temperature sensitivity of the superoxide-generating system in plants also suggests that this reaction is the key reaction responsible for the induction of resistance. Scavenging superoxide at an early stage in the tissue response resulted in suppression of these metabolic changes. Exposure of plant tissues to UV light is also assumed to generate superoxide immediately after exposure.
