The functions of TaLAD1-A1, Rht8, and Rht-D1b in regulating leaf angle in wheat.

key messageA genotypic pattern for breeding wheat with ideal plant architecture. Breeding wheat with reduced leaf angle represents a promising strategy for developing lines tolerant to high planting density, mitigating the adverse effects of shade avoidance and thus increasing yield potential. However, the molecular mechanisms underlying the reduced leaf angle phenotype remain poorly understood. In this study, a wheat mutant with a reduced leaf angle, designated lad1 and exhibiting impaired sensitivity to brassinosteroids (BRs), was isolated from an EMS-induced mutant library. Phenotypic analysis revealed that the reduced leaf angle in lad1 plants is due to a decrease in the size of lamina joint cells. Genetic mapping and cloning identified Talad1-A1, a single recessive nuclear gene located on chromosome 2A, is responsible for the variation in leaf angle. Furthermore, Rht8 and Rht-D1b have been shown to contribute significantly to leaf angle regulation. These findings deepen our understanding of the genetic and molecular mechanisms controlling leaf angle in wheat and provide a potential molecular selection strategy for the developing elite wheat varieties adapted to high-density planting.