Figure 3.

Crosslinking of ABA and light signaling on ABI5. Solid lines represent protein–protein interactions presented in PAIR, BioGRID, and IntAct, and dotted lines represent transcriptional regulation. ABA-responsive element binding factors of the ABA signaling network, such as ABF2, ABF4, and ABI3 (involved in abiotic stress defense and stress memory) cooperate with ABI5 to jointly regulate its function. Light signaling proteins PIF1, PIF4, FHY3/FAR1, and HY5 activate the expression of ABI5, whereas BBX21 inhibits its expression. FCA activates ABI5 by protein–protein interaction and jointly with ABI5 regulates expression of FLC. FLC and FCA are proteins that substantially reduce plant water use and are important for heat and cold adaptation. Red activator lines from FHY3/FAR1 and HY5 indicate cooperative effects HY5, DET1, and FHY3 signaling on ABI5 function (see also details in Figure 4). Abbreviations: ABI3,4,5, ABA insensitive 3,4,5; ABFs, abscisic acid responsive elements-binding factors; PIFs, phytochrome-interacting transcription factors; HY5, transcription factor HY5 (protein long hypocotyls 5); BBX21, B-box zinc finger transcription factor BBX21; FHY3/FAR1, far-red elongated hypocotyls 3/protein far-red impaired response 1; FCA, flowering time control protein; FLC, MADS-box protein flowering locus C.