Abstract
Circadian rhythms are generated by endogenous circadian clock system. In the past decade, molecular genetic analyses using Arabidopsis thaliana provided novel insights into the plant circadian clock system. A large number of circadian clock genes (CCGs) are involved in a complex gene network of the plant clock system. With systems biology analyses, the clock system in Arabidopsis was modeled as three transcriptional feedback loops (loop I, II and III) that consist of a single Myb genes (LHY/CCA1) and pseudo-response regulator genes (PRRs). However, a molecular phylogeny of these genes in angiosperm has not been determined. In order to clarify the phylogeny, we analyzed intron-exon structures, phylogenetic trees and chromosome syntenies among CCGs of three model plants (Arabidopsis, Rice and Poplar). We revealed that some CCGs were duplicated via whole genome duplication events and that, after these events, some duplicated CCGs were deleted from the genomes.
