Molecular bases and genetic improvement of rice grain size and quality for optimized yield and human health

Driven by growing consumer demand for healthier food, modern breeding increasingly focuses on biofortifying crops without compromising yield. Rice, as a widely consumed staple, holds significant potential for improving human health, whether through simultaneous improvement of grain size and overall quality to optimize yield or via multiple biofortification strategies that enhance nutritional value. Together, these key grain traits underpin the development of rice as a functional staple food. Advances in resolving the underlying genetic networks and biosynthetic pathways now offer practical avenues for regulating grain size and nutritional quality. This review summarizes recent progress in the regulation of grain size and nutritional quality in rice, as well as genetic improvement approaches, aiming to provide rational molecular design strategies for synergistically enhancing yield and quality. Furthermore, the multifunctional applications of improved grain are discussed to illustrate the potential for concurrent improvement in size and nutritional quality, thereby linking advances in sustainable rice production to human health outcomes.