Abstract
Plants must properly respond to daily light/dark cycles and changes in seasonal day-lengths. In such processes, a circadian clock plays crucial role. In the model higher plant Arabidopsis thaliana, it has been proposed that the central oscillator is composed of the Myb-related transcription factors CCA1 (LHY) and the pseudo response regulator PRR1/TOC1. The PRR1 clock component is a member of small family including PRR9, PRR7, PRR5, and PRR3. We already suggested that these PRR members all together play roles close to the circadian clock. To gain further insight into the clock-associated functions of PRRs, here we characterized a series of double prr mutants, such as prr5/prr7, prr5/prr9, prr7/prr9, with reference to the circadian-associated phenotypes. The results suggested that these PRRs play clock-associated roles coordinately and/or complementarily. These results will be discussed in the context of the current molecular model of the plant circadian clock.
