Premium
PIF 4‐induced BR synthesis is critical to diurnal and thermomorphogenic growth
Author(s) -
Martínez Cristina,
EspinosaRuíz Ana,
Lucas Miguel,
BernardoGarcía Stella,
FrancoZorrilla José M,
Prat Salomé
Publication year - 2018
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201899552
Subject(s) - biology , microbiology and biotechnology , biophysics , biochemistry
The Arabidopsis PIF 4 and BES 1/ BZR 1 transcription factors antagonize light signaling by facilitating co‐activated expression of a large number of cell wall‐loosening and auxin‐related genes. While PIF 4 directly activates expression of these targets, BES 1 and BZR 1 activity switch from a repressive to an activator function, depending on interaction with TOPLESS and other families of regulators including PIF s. 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 BES 1, PIF 4, and the BES 1‐ PIF 4 complex recognize different DNA elements, thus revealing a distinctive cis‐regulatory code beneath BES 1‐repressive and PIF 4 co‐activation function. BES 1 homodimers bind to conserved BRRE ‐ and G‐box elements in the BR biosynthetic promoters and inhibit their expression during the day, while elevated PIF 4 competes for BES 1 homodimer formation, resulting in de‐repressed BR biosynthesis at dawn and in response to warmth. Our findings demonstrate a central role of PIF 4 in BR synthesis activation, increased BR levels being essential to thermomorphogenic hypocotyl growth.