Rice Storage Proteins: Focus on Composition, Distribution, Genetic Improvement and Effects on Rice Quality

Rice storage proteins (RSPs) are plant proteins with high nutritional quality. As the second largest type of storage substance in rice, it is the main source of protein intake for people who consume rice as a staple food. The content and type of RSPs affect the appearance, processing quality and eating quality of rice. These effects involve the distribution of RSPs in rice grains as well as the interactions of RSPs with other components such as starch in rice grains. In the past two decades, some progress has been made in the genetic improvement of RSPs. However, the determination mechanism of protein content and composition in rice is still unclear, and the mechanism of the effect of RSPs on rice quality has not been elucidated. In this review, the composition, biosynthesis and distribution of RSPs, and quantitative trait loci mapping and cloning of RSP genes are summarized, the research progress of the influence of RSPs and their components on rice quality are reviewed, and the research directions in the future are proposed.