Plants grow on brassinosteroids

Brassinosteroids (BRs) are plant steroid hormones known mainly for promoting organ growth through their combined effect on cell expansion and division. In addition, BRs regulate a broad spectrum of plant developmental and physiological responses, including plant architecture, vascular differentiation, male fertility, flowering, senescence, photomorphogenesis and tolerance to biotic and abiotic stresses. Recently, a complete core BR signaling pathway was defined in which BR signals are conveyed from the cell surface to the nucleus through sequential signaling modules. A major challenge now is to understand precisely how this signaling pathway controls the different BR-regulated actions. The current identification of direct targets of BRASSINAZOLE-RESISTANT1 (BRZ1) and BR-INSENSITIVE-EMS-SUPPRESSOR1 (BES1)/BZR2 transcription factors suggests that BR signaling pathway controls growth and interacts with other signaling pathways mainly at the transcriptional level.

► Brassinosteroids regulate plant growth, development and stress responses.
► A complete brassinosteroid signaling cascade has recently been identified.
► Brassinosteroids control an extensive gene network through the transcription factors BZR1 and BES1/BZR2.
► Brassinosteroids regulate cell division to establish the root meristem size.
► Brassinosteroids control light responses at the transcriptional level.