FKF1, a clock-controlled gene that regulates the transition to flowering in Arabidopsis

Plant reproduction requires precise control of flowering in response to env ironmental cues. We isolated a late-flowering Arabidopsis mutant, fkf1, tha t is rescued by vernalization or gibberellin treatment. We positionally clo ned FKF1, which encodes a novel protein with a PAS domain similar to the fl avin-binding region of certain photoreceptors, an F box characteristic of p roteins that direct ubiquitin-mediated degradation, and six kelch repeats p redicted to fold into a beta propeller. FKF1 mRNA levels oscillate with a c ircadian rhythm, and deletion of FKF1 alters the waveform of rhythmic expre ssion of two clock-controlled genes, implicating FKF1 in modulating the Ara bidopsis circadian clock.