Poster: Clocks

Abs # 781: Forward and reverse genetic approaches to study the Arabidopsis circadian clock

Presenter:	McClung, C. Robertson , mcclung@dartmouth.edu
Authors	McClung, C. Robertson  (A)   Salomé, Patrice A. (A)   Michael, Todd P. (A)   Yu, Hannah J. (A)   Spencer, Taylor R. (A)   Sharp, Emily L. (A)   Colligan, James J. (A)   Olowoyeye, OmoLara  (A)
Affiliations:	(A): Dartmouth College
Web Site:	http://www.dartmouth.edu/~rmcclung/index.html

Rhythms with periods of approximately 24 hours are widespread in nature. Those that persist in constant conditions are termed circadian rhythms and reflect the activity of an endogenous biological clock. Although the clock is known to consist of a negative feedback loop, the components of the Arabidopsis thaliana clock have not all been identified, nor have the interactions among them been completely specified. Analysis of recombinant inbred lines between accessions Columbia and Landsberg erecta reveals much more variation in circadian parameters (period, phase, and amplitude) than is found in either parent. This is termed transgressive segregation and suggests that positive and negative alleles of multiple clock loci interact to determine clock characteristics. We have mapped Quantitative Trait Loci (QTL) for each clock parameter. Through loss of function and overexpression analysis, we have identified a number of loci that contribute to the establishment of period and phase and are candidate QTLs. These loci include the CRY1 and PHYB photoreceptors as well as each member of the ARABIDOPSIS PSEUDO-RESPONSE REGULATOR (APRR) family. The characterization of these loci and their contribution to the Arabidopsis clock will be discussed.