Defence induction was observed within 3 hpi for Pto and within 24 hpi for Hpa. Despite its rapid induction, this upregulation was not sustained with reduced expression observed by 24–72 hpi for Pto and ~72 hpi for Hpa. Although the response to biotrophic pathogens occurred over a delayed timecourse, presumably due to the requirement of the plant to detect infection, the response to biotic stressors displayed a similar expression profile as the response to exogenous SA application with a rapid induction followed by the deactivation of signaling within a relatively short timeframe. This evidence concerns the gene HPSE and infection.