Occurs in almost all aerobically respiring organisms and serves to protect cells from the toxic effects of hydrogen peroxide (By similarity). May prevent the excessive accumulation of H(2)O(2) during water stress in response to the accumulation of abscisic acid (ABA) (PubMed:21398647). Involved in the modulation of ROS levels related to root growth regulation (Ref.11). Required for pollen viability and floret fertility upon heat stress (HS) by detoxifying reactive oxygen species (ROS) and malondialdehyde (MDA) accumulation in developing anthers exposed to HS (PubMed:29464319). 2 H2O2 = 2 H2O + O2 Strongly inhibited by beta-mercaptoethanol, sodium azide and potassium cyanide. Slightly repressed by 3-amino-1,2,4-triazole (3-AT). Activity is repressed proportionally to increased concentration of NaCl, KCl, LiCl and MgCl(2). kcat is 20 min(-1) with H(2)O(2) as substrate (at pH 7.5). Optimum pH is 7.5. Optimum temperature is 25 degrees Celsius. Homotetramer (By similarity). Interacts with GLO1 and GLO4; these interactions are disturbed by alpha-hydroxy-2-pyridinemethanesulfonic acid (HPMS) and salicylic acid (SA) (PubMed:26900141). Interacts with STRK1 at the plasma membrane (PubMed:29581216). Predominantly expressed in roots and, at low levels, in leaves (e.g. sheaths) (PubMed:21398647, Ref.11, PubMed:26900141, PubMed:29464319). Detected in seeds (PubMed:21979082, PubMed:21398647, Ref.11, PubMed:29464319). Also present in panicles and culms (PubMed:22106097, Ref.11). Observed in stems and anthers (PubMed:29464319). Abundance in roots follows a diurnal oscillating expression pattern peaking during the night period (Ref.11). Induced by water stress and abscisic acid (ABA) in a concentration-dependent manner (PubMed:21398647, Ref.11). Activated by salicylic acid (SA) (PubMed:29464319). Repressed by ABA biosynthesis inhibitors nordihydroguaiaretic acid and tungstate under water stress (PubMed:21398647). Induced by high salinity (NaCl) and hydrogen peroxide (H(2)O(2)) treatments (Ref.11). Triggered by zinc oxide nanoparticles (ZnO NPs); this induction is reversed by sodium nitroprusside (SNP, a NO donor) (PubMed:25958266). Repressed by cadmium (Cd) (PubMed:28969789). Inhibited by heat stress (HS) (e.g. 35 degrees Celsius day/27 degrees Celsius night, 38 degrees Celsius day/30 degrees Celsius night) (PubMed:29464319). Belongs to the catalase family.