Advances in the Regulation of Rice (<i>Oryza sativa</i>) Grain Shape by Auxin Metabolism, Transport and Signal Transduction

Abstract: Rice (Oryza sativa) is a major food crop in the world. The optimization and utilization of the major yield-determining factors are important for increasing yield potential. Among these factors, seed weight is one of the most important factors determining rice production. The heritability of rice grain weight is stable, which is largely unaffected by environmental factors. Grain weight depends on grain shape, which is determined by grain length, grain width, and grain thickness, and the degree of grain filling. The growth of rice glumes and seed endosperm determines the grain shape and weight. The proliferation and expansion of glume cells affect grain development, and endosperm occupies most of the volume of mature seeds. Auxin is an important plant hormone that affects rice yield, which regulates the development of glume and endosperm after fertilization. The spatial-temporal distribution of active auxin is dynamically modulated by auxin metabolism, auxin transport and signal transduction, all of which maintain auxin at the optimal level for seed development. Here we reviewed the research progress of auxin pathways regulating rice grain shape from three aspects, auxin metabolism, auxin transport and auxin signal transduction, to provide clues for exploring the auxin regulation mechanism of grain shape and improve yield in rice.

Key words: rice, auxin metabolism, auxin transport, auxin signal transduction, grain shape