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Catalase is an iron porphyrin enzyme,which serves as an efficient scavenger of reactive oxygen species (ROS) to avoid oxidative damage.In sugarcane,the enzymatic activity of catalase in a variety (Yacheng05-179) resistant to the smut pathogen Sporisorium scitomineum was always higher than that of the susceptible variety (Liucheng03-182),suggesting that catalase activity may have a positive correlation with smut resistance in sugarcane.To understand the function of catalase at the molecular level,a cDNA sequence of ScCAT1 (GenBank Accession No.KF664183),was isolated from sugarcane infected by S.scitomineum.ScCAT1 was predicted to encode 492 amino acid residues,and its deduced amino acid sequence shared a high degree of homology with other plant catalases.Enhanced growth of ScCAT1 in recombinant Escherichia coli Rosetta cells under the stresses of CuC12,CdC12 and NaCI indicated its high tolerance.Q-PCR results showed that ScCAT1 was expressed at relatively high levels in the bud,whereas expression was moderate in stem epidermis and stem pith.Different kinds of stresses,including S.scitamineum challenge,plant hormones (SA,MeJA and ABA) treatments, oxidative (H202) stress,heavy metal (CuC12) and hyper-osmotic (PEG and NaCI) stresses,triggered a significant induction of ScCAT1.The ScCATl protein appeared to localize in plasma membrane and cytoplasm.Furthermore,histochemical assays using DAB and trypan blue staining,as well as conductivity measurement,indicated that ScCAT1 may confer the sugarcane immunity.In conclusion,the positive response of ScCAT1 to biotic and abiotic stresses suggests that ScCAT1 is involved in protection of sugarcane against reactive oxidant-related environmental stimuli.