Abstract
In order to dissect the mechanism of photoperiodic flowering, we have begun molecular analysis using two Lemna species; Lemna gibba G3 and L. paucicostata 6746 show strict photoperiodism as long day- and short day plants, respectively. We have focused on TOC1/APRR1 homologs of each species. Arabidopsis TOC1/APRR1 is a major factor in the oscillation machinery of circadian clock. This nuclear protein shows a sequence similarity to response regulators in the His-to-Asp phosphorelay. Four other genes closely related to TOC1/APRR1 have been identified in Arabidopsis. These five members are circadianly expressed and their peak phases sequentially reach one by one, and they appear to be involved in circadian clock, photoperiodic flowering, and photomorphogenesis. We report the isolation of homologs, expression analysis, and comparison between the long day- and the short day Lemna plants. The relationship between their expression manners and photoperiods will be discussed.
