Molecular Basis of the ABA Dependent Modulation of CONSTANS Activity in Drought Escape Response

Plants ability to adapt their development in response to environmental changes is one key factor underlying their evolutionary success. Phytohormones modulate different plant–environment interactions, namely the regulation of flowering time that is crucial to synchronize the onset of the reproductive phase with the most favorable conditions. In Arabidopsis thaliana the plant hormone abscisic acid (ABA), known to regulate various drought stress responses, promotes flowering under long day but not short day conditions. Genetic analyses support a model where ABA signals interact with the photoperiodic pathway, upstream of the flowering gene FLOWERING LOCUS T. Aims of my project are to define how ABA and photoperiod signaling interact. My genetic data indicates that ABA promotes flowering by modulating the activity of the FT activator CONSTANS (CO) rather than its transcriptional regulation. Initial data about the molecular basis of this ABA–CO interaction will be presented. Our study point to CO as the key integrator between ABA signals and the photoperiodic pathway, allowing plants to coordinate flowering time according to the prevailing watering conditions.