Red light and the dormancy-germination decision in Arabidopsis seeds

The Arabidopsis dormancy-germination transition is known to be environmentally-cued by red light and controlled by the competing hormones abscisic acid (ABA) and gibberellin (GA) produced by the seed. Recently, new molecular details emerged concerning the propagation of red light through a complex gene regulatory network involving PhyB, PIF1, and RVE1 and two feedback loops. This network influences the formation of the PIF1-RVE1 complex. The PIF1-RVE1 complex is a transcription factor that regulates the production of ABA and GA and helps shift the balance to high concentration of ABA and low concentration of GA, which corresponds to a dormant seed state. This new gene regulatory network has not been analyzed mathematically. Our analysis shows that this gene regulatory network exhibits switch-like bistability as a function of the red light input and makes a suite of biologically-testable predictions concerning seed dormancy and germination in response to the amplitude and periodicity of an oscillatory red light input.