It is worth noting that in plants SA specifically inhibits the H2O2-degrading activity of catalase (Chen et al., 1993) and of ascorbate peroxidase (Durner and Klessig, 1995), while SA treatment induces an increase in H202 concentrations in vivo, suggesting that SA may facilitate H2O2 accumulation during the oxidative burst induced by infection with avirulent pathogens (reviewed by Vlot et al., 2009). The gene discussed is CAT; the disease is infection.