Abstract
Circadian clock generates internal 24-h rhythm in plants, allowed them to predict changes of environment like daily and seasonal changes. Resent studies suggest CARCADIAN CLOCK ASSOCIATED 1(CCA1)/ LATE ELONGATED HYPOCOTYL(LHY), PSEUDO RESPONSE REGULATOR9/7/5, TIMIG OF CAB EXPRESSION 1(TOC1, also called PRR1), and GIGANTEA(GI) regulate each other in transcription, and form interlocked feedback loop in Arabidopsis.
Photoperiodic flowering induction is most important physiology regulated by clock, and arrows many plant to flower at their favorite seasons. Flowering is induced when CONSTANS(CO) gene expression coincides with the exposure of plants to light, in that condition, CO protein is highly stabilized. However, how circadian clocks induce CO gene expression at dusk is unknown.
By comparative genetics of cca1/lhy, prr7/5, and gi, we show circadian clocks induce CO at dusk via at least two pathways(PRR7/5-CO, and CCA1/LHY-GI-CO). And more, we discuss molecular mechanisms of these genes for the strict phase regulation of CO.
