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_crispr 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.

Glutinous rice has very low amylose content and is a good material for determining the structure and physicochemical properties of amylopectin. We selected 29 glutinous rice varieties and determined the amylopectin structure by high-performance anion exchange chromatography with the pulsed amperometric detection method. We also determined the correlation between amylopectin structure and the physicochemical properties of starch extracted from these varieties. The results showed that the amylopectin chain ratio Σdegree of polymerization (DP) ≤ 11/ΣDP ≤ 24 of 29 glutinous rice varieties was greater than 0.26, signifying that these varieties contained type II amylopectin. The results of the correlation analysis with gelatinization temperature showed that ΣDP 6–11 was significantly negatively correlated with the onset gelatinization temperature (GT) (T_O), peak GT (T_P), and conclusion GT (T_C). Among the thermodynamic properties, ΣDP 12–24 was significantly positively correlated with To, Tp, and Tc, ΣDP 25–36 was significantly negatively correlated with To, Tp, and Tc, and ΣDP ≥ 37 had no correlation with the thermodynamic properties. The results of correlation analysis with RVA spectrum characteristic values showed that ΣDP 6–11 was significantly negatively correlated with hot paste viscosity (HPV), cool paste viscosity (CPV), consistency viscosity (CSV), peak time (PeT), and pasting temperature (PaT) among the Rapid Visco Analyzer (RVA) profile characteristics, ΣDP 12–24 was significantly positively correlated with HPV, CPV, CSV, PeT, and PaT, and ΣDP ≥ 25 had no correlation with the viscosity characteristics. Therefore, we concluded that the amylopectin structure had a greater effect on the T_O, T_P, T_C, ΔH and peak viscosity, HPV, CPV, CSV, PeT, and PaT. The glutinous rice varieties with a higher distribution of short chains and a lower distribution of medium and long chains in the amylopectin structure resulted in lower GT and RVA spectrum characteristic values.

The leaf is the main site of photosynthesis and is an important component in shaping the ideal rice plant architecture. Research on leaf morphology and development will lay the foundation for high-yield rice breeding. In this study, we isolated and identified a novel curling leaf mutant, designated curling leaf 1 (cl1). The cl1 mutant exhibited an inward curling phenotype because of the defective development of sclerenchymatous cells on the abaxial side. Meanwhile, the cl1 mutant showed significant reductions in grain yield and thousand-grain weight due to abnormal leaf development. Through map-based cloning, we identified the CL1 gene, which encodes a MYB transcription factor that is highly expressed in leaves. Subcellular localization studies confirmed its typical nuclear localization. Transcriptome analysis revealed a significant differential expression of the genes involved in photosynthesis, leaf morphology, yield formation, and hormone metabolism in the cl1 mutant. Yeast two-hybrid assays demonstrated that CL1 interacts with alpha-tubulin protein SRS5 and AP2/ERF protein MFS. These findings provide theoretical foundations for further elucidating the mechanisms of CL1 in regulating leaf morphology and offer genetic resources for practical applications in high-yield rice breeding.