Abstract
The rapid production of reactive oxygen species (ROS) is a characteristic early feature of the hypersensitive response (HR) in plant innate immunity. Oxidative burst is known to be responsible for triggering defense responses in plants. Respiratory burst oxidase homologs (rboh genes) have been implicated in ROS generation. We have isolated two rboh cDNAs, StrbohA and StrbohB, from potato tubers. StrbohA was expressed constitutively at a low level, whereas StrbohB gene was induced by cell wall elicitor from the potato pathogen, Phytophthora infestans. Both Strboh proteins carry two calcium-binding EF hand motifs, suggesting that calcium influx into cytoplasm plays an important role in oxidative burst. In fact, calcium inhibitors negated the elicitor-induced oxidative burst and HR cell death but not transcriptional activation of StrbohB.
