Genetic Engineering of C4 Pathway Enzymes Enhances Limited Water Tolerance in C3 Rice

Stress like drought and salinity, are responsible for up to 70% of yield loss in crop plants. Improving drought tolerance in crops has thus become a critical agricultural priority. This study evaluates the physiological, morphological, and biochemical changes in transgenic rice plants engineered to overexpress key C4 photosynthetic enzymes like phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), and carbonic anhydrase (CA). The transgenic lines demonstrated enhanced drought tolerance, as evidenced by higher relative water content (RWC), chlorophyll retention, and photosynthetic rate under limited water stress compared to wild-type (WT) plants. Additionally, greater oxidative stress mitigation was observed due to improved antioxidant activity and increased proline accumulation. The physiological and structural enhancements in transgenic lines are likely attributed to synergistic effects of the introduced C4 genes, which may improve CO2 availability and assimilation efficiency. The findings suggest that introducing C4 enzymes into C3 plants like rice offers a promising strategy for improving drought resilience and overall productivity.