Abstract
Circadian rhythms are driven by endogenous biological clocks that regulate many processes in a wide variety of organisms. At least 4 genes, LHY, CCA1, TOC1 and GI, have been shown to be closely associated with clock function in Arabidopsis. Loss-of-function of either LHY or CCA1 shortens the period of the rhythm in the expression of clock-controlled genes under continuous light, and also accelerates flowering under short days (SD). To identify more mutations which affect circadian rhythms, we have screened EMS-mutagenised lhy-12 seeds for plants which flowered earlier than the lhy-12 in SD. We found that two mutations, 38elf-1 and 70elf-1, in a similar way to the cca1, enhanced 1) early flowering phenotype in SD and 2) shift in the phase of expression of GI, of the lhy-12 mutant. Characterization of these enhancer mutations is underway. They may define further cca1 loss-of-function alleles or genes required for CCA1 regulation.
