Abstract
Many plants monitor seasonal changes in day length in order to regulate flowering time for successful reproduction. We focused on the liverwort, M.polymorpha, to understand the origin and evolution of growth-phase transitions regulated by the photoperiod. M.polymorpha belongs to a group of basal land plants, and was reported to be a long-day plant. Firstly, we searched for genes associated with the photoperiod pathway in M.polymorpha genome database, and found homologues of TOC1/PRR family gene, GI and ADO/FKF/LKP/ZTL family gene. These genes were named as MpTOC1, MpPRR2, MpGI and MpFKF1, respectively. Phylogenetic analysis supported the orthologous relationship of these genes to their homologues in vascular plants. Furthermore, northern blot analyses showed rhythmic expression pattern of MpGI, MpTOC1, and MpPRR2 under LD conditions. The phase peaks of these genes were similar to those in vascular plant. Interestingly, expression level of MpPRR2 was lower in MpPHY RNAi-line than in WT, suggesting positive regulation of MpPRR2 by Mpphy. Taken together, these results suggest that M.polymorpha would have a basic and simple regulatory mechanism of its circadian clock.
