Abstract
In Arabidopsis thaliana, the transcripts of the APRR1 family genes start each accumulating after dawn rhythmically and one after another at intervals in the order of APRR9, APRR7, APRR5, APRR3, APRR1 under continuous light. APRR1 is identical to TOC1 that is believed to be a component of the central oscillator. Except for the well-characterized APRR1/TOC1, no evidence has been provided that other APRR1/TOC1 family genes are indeed implicated in the mechanisms underlying circadian rhythms. We here attempted to provide such evidence by characterizing transgenic plants that constitutively express the APRR9 gene, and T-DNA insertion mutants of APRR9. Several lines of solid evidence will be presented to show that APRR9 (together with APRR1/TOC1) must be taken into consideration for a better understanding of the molecular links between circadian rhythms, control of flowering time through the photoperiodic long-day pathway, and also light signaling-controlled plant development.
