The Role of Sugarcane Catalase Gene in the Defense Response to Pathogen Challenge and Adversity Stress

Catalases, which consist of multiple structural isoforms, catalyze the decomposition of hydrogen peroxide in cells to prevent membrane lipid peroxidation. In this study, a group II catalase gene (GenBank Accession No. KF528830) was isolated from sugarcane genotype Yacheng05-179. encoded a predicted protein of 493 amino acid residues, including a catalase active site signature (FARERIPERVVHARGAS) and a heme-ligand signature (RVFAYADTQ). Subcellular localization experiments showed that the ScCAT2 protein was distributed in the cytoplasm, plasma membrane, and nucleus of epidermal cells. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the gene was ubiquitously expressed in sugarcane tissues, with expression levels from high to low in stem skin, stem pith, roots, buds, and leaves. mRNA expression was upregulated after treatment with abscisic acid (ABA), sodium chloride (NaCl), polyethylene glycol (PEG), and 4 °C low temperature, but downregulated by salicylic acid (SA), methyl jasmonate (MeJA), and copper chloride (CuCl₂). Moreover, tolerance of Rosetta cells carrying pET-32a- was enhanced by NaCl stress, but not by CuCl₂ stress. infection of 10 different sugarcane genotypes showed that except for YZ03-258, FN40, and FN39, transcript abundance in four smut-resistant cultivars (Yacheng05-179, YZ01-1413, YT96-86, and LC05-136) significantly increased at the early stage (1 day post-inoculation), and was decreased or did not change in the two smut-medium-susceptibility cultivars (ROC22 and GT02-467), and one smut-susceptible cultivar (YZ03-103) from 0 to 3 dpi. Meanwhile, the leaves that transiently overexpressed exhibited less severe disease symptoms, more intense 3,3'-diaminobenzidine (DAB) staining, and higher expression levels of tobacco immune-related marker genes than the control after inoculation with tobacco pathogen or var. . These results indicate that plays a positive role in immune responses during plant⁻pathogen interactions, as well as in salt, drought, and cold stresses.