A genetic study on the Arabidopsis circadian clock genes with reference to an interlocking multi-loop model

Abstract

With regard to the Arabidopsis circadian clock, an interlocking multi-loop clock model has been currently acknowledged. This tentative model consists of three interactive feedback loops, namely, core CCA1/LHY-TOC1/X loop, morning CCA1/LHY-PRR9/PRR7 loop, and evening Y-TOC1 loop, in which the undefined Y gene might be GI and/or PRR5. To evaluate this model, we already characterized a prr9 prr7 double loss-of-function mutant that had lost the morning loop, and a cca1 lhy toc1 triple mutant that lacks the core loop. To extend these lines of genetic studies, here we characterized a gi toc1 and gi prr5 double loss-of-function mutants that are expected to have no evening loop, and a prr9 prr7 toc1 triple mutant that lacks both the morning and evening loops. The results will be discussed extensively with reference to the current clock model, including the possible functions of GI and PRR.