Abstract
Photoperiodic flowering is established through the interaction between the circadian clocks and the external light signaling. The extensive molecular genetics has been done on the circadian clocks in Arabidopsis, but not in rice. We have demonstrated that the circadian clocks works properly during the daily cycles in se5 mutants, which lose the response of flowering to the photoperiods due to a phytochrome deficiency. To understand the roles of circadian clocks in the photoperiodic flowering of rice at the molecular levels, we screened several suppressor mutants of se5, which caused significant late flowering under natural conditions among ca. 15,000 M2 plants derived from ca. 3,000 gamma ray- mutagenized se5 seeds. The mRNA expression analysis of some rice genes orthologous to the Arabidopsis circadian clock- genes such as OsGI, OsPRR1, OsLHY, using these se5 suppressor mutants revealed how the circadian-clocks are involved in the genetic network of the photoperiodic flowering in rice.
