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FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis

TitleFKF1 is essential for photoperiodic-specific light signalling in Arabidopsis
Publication TypeJournal Article
Year of Publication2003
AuthorsImaizumi T, Tran HG, Swartz TE, Briggs WR, Kay SA
Date Published2003
ISBN Number1476-4687 (Electronic)0028-0836 (Linking)
Keywords*Light, *Photoperiod, *Signal Transduction, Arabidopsis Proteins/genetics/*metabolism, Arabidopsis/genetics/*physiology, Circadian Rhythm, Color, DNA-Binding Proteins/genetics, Flowers/genetics/physiology, Gene Expression Regulation, Plant, Genes, Plant/genetics, Protein Structure, Tertiary, Seasons, Universities, Transcription Factors/genetics

<p>Adaptation to seasonal change is a crucial component of an organism&#39;s survival strategy. To monitor seasonal variation, organisms have developed the capacity to measure day length (photoperiodism). Day-length assessment involves the photoperiodic control of flowering in Arabidopsis thaliana, whereby the coincidence of light and high expression of CONSTANS (CO) induces the expression of FLOWERING LOCUS T (FT), leading to flowering in long-day conditions. Although controlling CO expression is clearly a key step in day-length discrimination, the mechanism that generates day-length-dependent CO expression remains unknown. Here we show that the clock-controlled FLAVIN-BINDING, KELCH REPEAT, F-BOX (FKF1) protein has an essential role in generating the diurnal CO peak and that this function is dependent on light. We show that a recombinant FKF1 LIGHT, OXYGEN OR VOLTAGE (LOV) domain binds the chromophore flavin mononucleotide and undergoes light-induced photochemistry, indicating that FKF1 may function as a photoperiodic blue-light receptor. It is likely that the circadian control of FKF1 expression and the light regulation of FKF1 function coincide to control the daytime CO waveform precisely, which in turn is crucial for day-length discrimination by Arabidopsis.</p>