Abstract

Significance As one of the most important growth-promoting hormones, auxin regulates many aspects of plant growth and development. Understanding auxin action has long been a challenging task because of the complexity of the hormone transport involved in auxin response. Despite tremendous progress made in Arabidopsis , auxin response and transport are poorly understood in crop plants, which impedes the application of hormone knowledge in agricultural improvement. This study not only identifies a novel positive regulator of plant growth in rice and demonstrates its significant role in improving seed size and grain yield, it also illustrates the specific involvement of the plasma membrane-associated protein in regulating auxin response and transport, thus illuminating a new strategy for enhancing crop productivity.