Chaperone-like protein DAY plays critical roles in photomorphogenesis

Abstract Photomorphogenesis, light-mediated development, is an essential feature of all terrestrial plants. While chloroplast development and brassinosteroid (BR) signaling are known players in photomorphogenesis, proteins that regulate both pathways have yet to be identified. Here we report D E-ETIOLATION IN THE DARK A ND Y ELLOWING LIGHT (DAY) , a membrane protein containing DnaJ-like domain, plays dual-role photomorphogenesis by stabilizing the BR receptor, BRI1, as well key enzyme chlorophyll biosynthesis, POR. DAY localizes endomembrane chloroplasts via its first transmembrane domain transit peptide, respectively, interacts with BRI1 POR their respective subcellular compartments. Using genetic analysis, show acts independently on biogenesis. Collectively, this work uncovers factor simultaneously regulates revealing regulator across cell