LAZY5 acts in an LAZY1-independent pathway to regulate rice tiller angle

Tiller angle is a key agronomic trait that influences plant architecture and thus grain yield by optimizing rice planting density. Although great progress has been made in understanding the LAZY1-dependent pathway mediating rice tiller angle, the genetic regulatory network of rice tiller angle remains to be elucidated. Here, we identified a new tiller angle gene LAZY5 (LA5) that encodes a member of the ATP binding cassette transporter G subfamily (ABCG) transporter. We found LA5 can interact with OsPIN3t to regulate lateral auxin transport (LAT), shoot gravitropism, and thus tiller angle. Further genetic analysis demonstrated that LA5 acts in a novel LA1-independent pathway to modulate LAT and rice tiller angle. Up-regulation of LA5 not only enlarges tiller angle but also increases tiller number in rice. Moreover, LA5 was strongly selected during rice domestication, with haplotype differentiations happened within the indica rice population. Our study not only uncovers a novel LA1-independent pathway controlling LAT and shoot gravitropism, but also provides a potential molecular target for high-yield breeding via synergistically regulating rice tiller angle and tiller number.