Bioengineering of Canopy Photosynthesis in Rice for Securing Global Food Security: A Critical Review

The emerging threat of climate change is posing a scientific conundrum for global food and nutritional security. As a primary staple food, half of the global human population is supported by rice crop. Thus, enhancing rice yield is highly critical to ensure food security. Photosynthesis is the defining physiological process of plants that determines maximum attainable yield. Efficiently capturing solar radiation and converting the carbon assimilates into rice grain is critical to achieve high yield. Genetic interventions to modify the plant architecture for enhanced light capture can improve rice yield significantly. Enhancement of cellular photosynthesis by synthetic biology approaches targeting important nodes of the light harvesting and carbon assimilation pathways are critical for breaking yield ceiling. The possible targets for improving photosynthesis include the light capture, chloroplast electron transport, Calvin cycle enzymes, sugar transport mechanisms, minimization of photorespiration, and improving source-sink relations. Conversion of C-3 rice into a C-4 type plant is also an option being vigorously pursued. Here, we review the determinants of canopy photosynthesis in rice with special reference to genetic factors and cellular photosynthetic capacity.