Abstract
In many organisms, a wide variety of biological processes are controlled by circadian rhythms. Two Myb-related genes, LHY and CCA1, have been shown to be closely associated with clock function in Arabidopsis. Lack of LHY or CCA1 shortens the period of the rhythm in the expression of clock-controlled genes under continuous conditions, and also accelerates flowering under short days. lhy cca1 double mutant plants flower much earlier than the progenitor single mutants and lose free-running rhythms in constant light. Loss-of-function of a blue light receptor gene, FHA/CRY2 or a floral inducer gene, CO, causes late flowering phenotype and decreased expression of a floral activator gene, FT, under long days. To understand molecular mechanisms on photoperiodic control of flowering, we have tested genetic interactions among LHY and CCA1, CO and FHA/CRY2. Our results suggest that both CO and FHA/CRY2 are downstream factors of LHY and CCA1 to control flowering.
