Translatome analyses capture of opposing tissue-specific brassinosteroid signals orchestrating root meristem differentiation

Brassinosteroid (BR) differentially regulates the number of stem cell daughters in the root meristem. How its activity coordinates and maintains the meristem size remains unknown. We show that BR signal coordinates root growth by evoking distinct and often opposing responses in specific tissues. Whereas epidermal BR signal promotes stem cell daughter proliferation, the stele-derived BR signal induces their differentiation. Using a comprehensive tissue-specific translatome survey, we uncovered a context-specific effect of BR signaling on gene expression. Auxin genes, activated by epidermal BR perception, are necessary for induction of cell division. Conversely, the stele BR perception, accompanied by gene repression, restrains the epidermal effect. Therefore, a site-specific BR signal is essential for balanced organ growth.