Involvement of Arabidopsis Clock-Associated Pseudo-Response Regulators in Diurnal Oscillations of Gene Expression in the Presence of Environmental Time Cues

Abstract

The circadian clock is implicated in the several cellular and physiological activities in plants. It must be synchronized to local time by environmental time cues. In Arabidopsis, although many clock-associated components have been uncovered, the clock-associated elements that are involved in entrainment are largely unknown. We have been characterizing one core group of clock components that control the pace of the central oscillator, including PRR9, PRR7, PRR5, and TOC1. In this study, the diurnal oscillation profiles of clock-controlled genes in the presence of environmental time cues were examined in a set of prr mutants. As an extreme phenotype, the prr9-10 prr7-11 prr5-11 toc1-2 quadruple mutant showed an arrhythmia phenotype even under light/dark and hot/cold cycles. Here, we will propose that the clock components PRR9, PRR7, and PRR5 together might represent elements necessary for the circadian clock to properly entrain to local time in response to environmental time cues.