PIF4‐induced BR synthesis is critical to diurnal and thermomorphogenic growth

Martínez, Cristina; Espinosa‐Ruíz, Ana; de Lucas, Miguel; Bernardo‐García, Stella; Franco‐Zorrilla, José M; Prat, Salomé

Abstract

The Arabidopsis PIF4 and BES1/BZR1 transcription factors antagonize light signaling by facilitating co‐activated expression of a large number of cell wall‐loosening and auxin‐related genes. While PIF4 directly activates expression of these targets, BES1 and BZR1 activity switch from a repressive to an activator function, depending on interaction with TOPLESS and other families of regulators including PIFs. However, the complexity of this regulation and its role in diurnal control of plant growth and brassinosteroid (BR) levels is little understood. We show by using a protein array that BES1, PIF4, and the BES1‐PIF4 complex recognize different DNA elements, thus revealing a distinctive cis‐regulatory code beneath BES1‐repressive and PIF4 co‐activation function. BES1 homodimers bind to conserved BRRE‐ and G‐box elements in the BR biosynthetic promoters and inhibit their expression during the day, while elevated PIF4 competes for BES1 homodimer formation, resulting in de‐repressed BR biosynthesis at dawn and in response to warmth. Our findings demonstrate a central role of PIF4 in BR synthesis activation, increased BR levels being essential to thermomorphogenic hypocotyl growth.

Citation

Martínez, C., Espinosa‐Ruíz, A., de Lucas, M., Bernardo‐García, S., Franco‐Zorrilla, J. M., & Prat, S. (2018). PIF4‐induced BR synthesis is critical to diurnal and thermomorphogenic growth. The EMBO Journal, 37(23), Article e99552. https://doi.org/10.15252/embj.201899552

• Journal Article Type: Article
• Acceptance Date: Sep 27, 2018
• Online Publication Date: Nov 2, 2018
• Publication Date: Nov 2, 2018
• Deposit Date: Jan 4, 2019
• Publicly Available Date: May 2, 2019
• Journal: EMBO Journal
• Print ISSN: 0261-4189
• Electronic ISSN: 1460-2075
• Publisher: EMBO Press
• Peer Reviewed: Peer Reviewed
• Volume: 37
• Issue: 23
• Article Number: e99552
• DOI: https://doi.org/10.15252/embj.201899552
• Public URL: https://durham-repository.worktribe.com/output/1311007