Specificity of brassinosteroid perception and its integration at signaling crossroads in vascular development

Brassinosteroids (BRs) are key regulators of plant growth and development. The BR receptor BRASSINOSTEROID-INSENSITIVE 1 (BRI1) is broadly expressed across root tissues, yet classical genetic studies suggested that BR signaling can also act non-cell-autonomously. Nevertheless, recent advances-based on tissue-specific CRISPR, state-of-the-art imaging and single-cell transcriptomics-reveal that BR perception operates largely cell-autonomous and strongly context-dependent. Here, we also review emerging evidence demonstrating that BR signaling is spatially confined and mechanistically integrated with other signaling pathways to regulate tissue-specific developmental outcomes. Rather than acting as a uniform growth trigger, BR functions as a modular, locally tuned regulator coordinating plant development via both canonical and non-canonical pathways.