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First published online February 3, 2006; 10.1104/pp.105.074518 Plant Physiology 140:1464-1474 (2006) © 2006 American Society of Plant Biologists
Analysis of Phase of LUCIFERASE Expression Reveals Novel Circadian Quantitative Trait Loci in Arabidopsis1,[W]Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom (C.D., B.L.T., H.G.M.); Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh EH9 3JH, United Kingdom (K.D.E., P.E.B.); and School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom (A.H.)
In response to exogenous rhythms of light and temperature, most organisms exhibit endogenous circadian rhythms (i.e. cycles of behavior and gene expression with a periodicity of approximately 24 h). One of the defining characteristics of the circadian clock is its ability to synchronize (entrain) to an environmental rhythm. Entrainment is arguably the most salient feature of the clock in evolutionary terms. Previous quantitative trait studies of circadian characteristics in Arabidopsis (Arabidopsis thaliana) considered leaf movement under constant (free-running) conditions. This study, however, addressed the important circadian parameter of phase, which reflects the entrained relationship between the clock and the external cycle. Here it is shown that, when exposed to the same photoperiod, Arabidopsis accessions differ dramatically in phase. Variation in the timing of circadian LUCIFERASE expression was used to map loci affecting the entrained phase of the clock in a recombinant population derived from two geographically distant accessions, Landsberg erecta and Cape Verde Islands. Four quantitative trait loci (QTL) were found with major effects on circadian phase. A QTL on chromosome 5 contained SIGNALING IN RED LIGHT REDUCED 1 and PSEUDORESPONSE REGULATOR 3, both genes known to affect the circadian clock. Previously unknown polymorphisms were found in both genes, making them candidates for the effect on phase. Fine mapping of two other QTL highlighted genomic regions not previously identified in any circadian screens, indicating their effects are likely due to genes not hitherto considered part of the circadian system.
1 This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC; grant no. 43/G17845 to H.G.M.) and a BBSRC studentship (to C.D.). H.G.M. is a Royal Society University Research Fellow. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Harriet G. McWatters (harriet.mcwatters{at}plants.ox.ac.uk). [W] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.074518. * Corresponding author; e-mail harriet.mcwatters{at}plants.ox.ac.uk; fax 441865275074. Received November 22, 2005; returned for revision January 26, 2006; accepted January 26, 2006. This article has been cited by other articles:
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