CRY1 interacts with BES1 to regulate BR signaling and photomorphogenesis (Plant Cell)

Plants perceive blue light through cryptochrome (CRY) photoreceptors that are responsible for photomorphogenesis, flowering, and circadian rhythms. At the same time, brassinosteroid (BR) represses photomorphogenesis. In this article, Wang et al. demonstrated CRY1-mediated inhibition of BR signaling as a potential mechanism. In dark conditions, inactivated CRY1 does not interact with dephosphorylated BES1 (BRI1-EMS SUPPRESSOR1), a transcription factor invovled in the BR signaling pathway. In the presence of light, activated CRY1 interacts with dephosphorylated BES1 through its N terminal end (CNT1) and inhibits the DNA binding capacity of BES1. In the presence of BR, BES1 is mostly in the dephosphorylated form that CRY1 does not interact with. Altogether this study suggests that CRY1-BES1 interaction inhibits the DNA binding ability of BES1 and consequently represses downstream gene expression, revealing a balance between external light and internal BR signals for plant photomorphogenesis. (Summary by Arif Ashraf) Plant Cell 10.1105/tpc.17.00994