Abstract
The Lemna genus in duckweeds includes two species that show photoperiodic flowering responses of a long-day type (L. gibba) and a short-day type (L. paucicostata). We tried to reveal the molecular basis for their timing systems. We isolated a number of Lemna homologues of circadian clock-related genes of Arabidopsis. We then tried establishing the methods for analysis of functions of those homologues in the Lemna plants. To monitor the circadian rhythm, we developed a bioluminescent reporter system in which the luciferase gene under a circadian promoter was introduced by using a particle bombardment method. Then, this semi-transient bioluminescence monitoring system was combined with overexpression/RNAi procedures to manipulate the expression levels of clock-related homologues. This enabled us to try various combinations of effectors/promoter-reporters for an approach to the gene network underlying the circadian system. Physiological functions of Lemna clock-related homologues and the comparison with those in Arabidopsis will be discussed.
