Harmer Lab:NIH

Molecular analysis of Arabidopsis circadian regulation
Funded by National Institute of General Medical Sciences

Senior Personnel

 * PI: Stacey Harmer

Abstract
Circadian rhythms, found widely in nature, are physiological cycles produced by an internal oscillator or clock that have a period of roughly 24 hours. They provide organisms with an adaptive advantage, presumably by allowing them to coordinate growth and physiology with daily changes in the environment that occur as a consequence of the earth’s rotation. Despite similarities in circadian physiology across higher taxa, most molecules involved in clock function are not conserved. The study of circadian clocks in multiple model systems therefore provides us with alternate views of how living cells keep track of time. My lab is interested in understanding how the plant clock works and why it is important for fitness. Circadian rhythms influence most aspects of plant physiology, including photosynthesis, stress responses, and cell elongation. We would like to understand both the molecular machinery underlying the plant clock and how it generates these important outputs that regulate plant growth and development.

Despite recent progress made possible by genomic, genetic, and mathematical approaches, the nature of the core oscillator in higher plants is still debated. Some core oscillator components have been tentatively identified, but the function of many of these gene products and even their placement within the circadian system has yet to be unequivocally determined. Furthermore, predicted components of the clock have yet to be identified. A basic understanding of circadian circuitry in plants, which is now lacking, requires the identification of more clock components and an exploration of how they work with each other to regulate clock outputs.

In our previous work, we identified genes that act near the central clock and affect clock-controlled processes such as growth. Here, we propose to study the molecular functions of these novel genes and to clone a new clock mutant identified in a sensitized genetic background. We will use genetic, genomic, and biochemical techniques to place these gene products within the architecture of the plant clock. Further, we will study links between the plant clock and regulation of development. This work will have important implications for understanding both the makeup of the plant clock and how circadian clocks can influence physiology in general.