Analysis of CAT Gene Family and Functional Identification of OsCAT3 in Rice

Catalase (CAT) is an important antioxidant enzyme in plants that plays a key role in plant growth and stress responses. CAT is usually encoded by a small gene family that has been cloned and functionally studied in some species, such as Arabidopsis, wheat and cucumber, but its specific roles in rice are not clear at present. In this study, we identified three CAT family genes (OsCAT1, OsCAT2 and OsCAT3) in the rice genome and performed a systematic bioinformatics analysis. RT-PCR analysis revealed that OsCAT1-OsCAT3 was primarily expressed in vegetative tissues such as roots, stems and leaves. Since OsCAT3 showed the highest expression level among the three OsCAT genes, we then focused on its related functions. OsCAT3 prokaryotic expression protein has an obvious ability to remove H₂O₂. The OsCAT3 plant was short and had a low survival rate, the leaves were small with brown lesions, and the activities of the CAT, POD and SOD enzymes were significantly reduced. A microarray analysis showed that differentially expressed genes were primarily enriched in toxin metabolism and photosynthesis. This study laid a foundation for further understanding the function of the rice OsCAT gene.