Abstract
It has totally remained a mystery about the evolution and origin of circadian clocks in plants, because the studies on the molecular mechanism of the plant clock have so far mostly been limited to Arabidopsis thaliana. To obtain some hints about this mystery, we started to study the circadian clock using the moss Physcomitrella patens. Previously, we reported that clock-controlled genes of this moss showed rhythmic expression in continuous dark, while they were completely arrhythmic in continuous light (LL). This is contrasting to the cases of higher plants, which show robust circadian rhythms of gene expression in LL. We report here the results of recent analyses on a Physcomitrella homolog of the Arabidopsis clock gene PCL1, and phylogenetic relationships between the clock gene homologs in plants.
