Decoding the Hormonal, Genetic, and Environmental Signals Regulating Leaf Angle in Plants

Plant architecture is a key determinant of canopy structure, light interception, photosynthetic efficiency and overall biomass production. In response to changing environmental conditions, plants dynamically adjust their growth and architectural traits to optimize resource use and productivity. Leaf angle (LA) is one of the vital agronomic traits that influences leaf orientation, with erect leaf phenotypes enhancing light capture, nitrogen use efficiency and yield, particularly advantageous in high-density planting systems. This review provides a comprehensive overview of the hormonal and genetic regulatory networks that control leaf structure and specifically LA. It highlights the role of major phytohormones pathways, including brassinosteroids (BR), auxin (IAA), gibberellins (GA), and cytokinins (CKs), with an emphasis on their roles in shaping leaf architecture. BR signaling, in particular, emerges as a central hub, coordinating developmental responses through extensive crosstalk with IAA, GA, and other signaling cascades. Additionally, this review also explores how environmental constraints interact with hormonal and transcriptional dynamics of these pathways to modulate LA, highlighting the complex interplay between intrinsic genetic programs and external conditions. Overall, this review explores current insights into the key genes, signaling pathways, molecular networks, and diverse environmental factors involved in LA regulation. It emphasizes their practical significance in plant architectural optimization and implications for high-density planting adaptability, crop improvement and sustainable agricultural productivity.