Abstract
In the model higher plant Arabidopsis thaliana, a number of circadian clock-associated protein components have recently been identified. Among them, a small family of ARABIDOPSIS PSEUDO-RESPONSE REGULATOR (APRRs) < is interesting because the most probable clock component TIMINING OF CAB EXPRESSION 1 (TOC1) belongs to this family. Here we dissected the regulatory cis-elements of the light-induced and/or circadian-controlled APRR9 promoter, by employing not only a mutant plant carrying a T-DNA insertion in the APRR9 promoter, but also a series of APRR9-promoter::LUC (luciferase) reporters that were introduced into an Arabidopsis cultured cell line (T87). we provided several lines of evidence for that the APRR9 promoter contains at least two distinctive and separable regulatory cis-elements: namely, "L element" responsible for the light-induced expression, which is followed by "R element" necessary for the fundamental rhythmic expression of APRR9. Furthermore, APRR1/TOC1 was implicated in the L-element-mediated light response of APRR9, directly or indirectly.
