Identification of circadian-regulated genes of Arabidopsis thaliana.

Most higher organisms, including plants and animals, have developed a time-keeping mechanism that allows them to anticipate daily fluctuations of environmental parameters such as light and temperature. This circadian clock efficiently coordinates plant growth and metabolism with respect to time-of-day by producing self-sustained rhythms of gene expression with an approximately 24-hour period. The importance of these rhythms has in fact been demonstrated in both phytoplankton and higher plants: organisms that have an internal clock period matched to the external environment possess a competitive advantage over those that do not. We used microarrays to identify circadian-regulated genes of Arabidopsis thaliana to elucidate how the clock provides an adaptive advantage by understanding how the clock regulates outputs and determining which pathways and processes may be under circadian control. Keywords: time course Groups of Arabidopsis seedlings were grown in light/dark cycles for 7 d before, transferred to constant light, and after 24 h in constant light 12 samples were harvested at 4-h intervals over the next 44 h for RNA extraction and hybridization on Affymetrix microarrays.