CAT and infection: Without pathogen infection, CAT-deficient mutants show SA accumulation, induced expression of the SA-pathway marker gene PR1 (pathogenesis-related 1), cell death, along with H2O2 accumulation in tobacco (Takahashi et al., 1997; Chamnongpol et al., 1998; Mittler et al., 1999) and Arabidopsis (Chaouch and Noctor, 2010; Chaouch et al., 2010).