Spatial control of plant steroid signaling

Two recent studies disclose the interaction between brassinosteroids (BRs) and cell-identity genes in establishing organ boundaries. BR signaling is downregulated by LATERAL ORGAN BOUNDARIES (LOB), whereas active BR signaling prevents LATERAL ORGAN FUSION1 (LOF1) and CUP SHAPED COTYLEDON (CUC) expression in the growing primordia, pointing to cell-specific hormone signaling as part of the mechanisms controlling fate acquisition.