Integration of light, carbon, and nitrogen pathways in regulating rice yield

Rice productivity arises from an interdependent system: optimal nitrogen utilization enables efficient light signaling, photosynthetic energy capture, and carbon fixation (ultimately yielding carbohydrates), while these processes are fine-tuned by the nitrogen status they regulate, collectively optimizing growth and yield. Light signaling, mediated by photoreceptors, converts environmental cues into transcriptional reprogramming that elicits specific cellular responses. Concurrently, photosynthesis converts light into chemical energy and sugar signals that orchestrate plant growth and development. Nitrogen serves not only as a fundamental building block for all core biomolecules but also as a master regulatory signal, ultimately determining crop yield by governing both the physical structure and developmental programs of plants. The synergistic coordination of light, carbon, and nitrogen metabolism thus underlies crop productivity by regulating carbon-nitrogen balance and associated physiological processes. This review summarizes the dual role of light as both a signal and an energy source, and its integration with sugar and nitrogen metabolism across multiple biological levels to shape yield traits in rice. We further analyze how key transcription factor networks function as central hubs, integrating light, carbon, and nitrogen pathways to enhance photosynthetic capacity, nitrogen assimilation, and reproductive development, providing strategic insights for breeding high-yielding rice varieties with superior resource-use efficiency.