The whole and its parts: cell-specific functions of brassinosteroids

Brassinosteroid (BR) phytohormones operate at both the cellular and organ levels, and impart distinct transcriptional responses in different cell types and developmental zones, with distinct effects on organ size and shape. Here, we review recent advances implementing high-resolution and modeling tools that have provided new insights into the role of BR signaling in growth coordination across cell layers. We discuss recently gained knowledge on BR movement and its relevance for intercellular communication, as well as how local protein environments enable cell- and stage-specific BR regulation. We also explore how tissue-specific alterations in BR signaling enhance crop yield. Together, we offer a comprehensive view of how BR signaling shapes the whole (overall growth dynamics) through its parts (intricate cellular interactions).