TAC4 controls tiller angle by regulating the endogenous auxin content and distribution in rice

Abstract Tiller angle, an important component of plant architecture, greatly influences the grain yield of rice ( Oryza sativa L.). Here, we identified Tiller Angle Control 4 ( TAC4 ) as a novel regulator of rice tiller angle. TAC4 encodes a plant‐specific, highly conserved nuclear protein. The loss of TAC4 function leads to a significant increase in the tiller angle. TAC4 can regulate rice shoot gravitropism by increasing the indole acetic acid content and affecting the auxin distribution. A sequence analysis revealed that TAC4 has undergone a bottleneck and become fixed in indica cultivars during domestication and improvement. Our findings facilitate an increased understanding of the regulatory mechanisms of tiller angle and also provide a potential gene resource for the improvement of rice plant architecture.