Natural variation reveals that intracellular distribution of ELF3 protein is associated with function in the circadian clock.

Muhammad Usman Anwer,Seth Jon Davis,Eva Herrero,Geo Velikkakam James,Ferenc Nagy,Eleni Boikoglou,Amanda Melaragno Davis,Marc Hallstein

doi:10.7554/elife.02206

Abstract

Natural selection of variants within the Arabidopsis thaliana circadian clock can be attributed to adaptation to varying environments. To define a basis for such variation, we examined clock speed in a reporter-modified Bay-0 x Shakdara recombinant inbred line and localized heritable variation. Extensive variation led us to identify EARLY FLOWERING3 (ELF3) as a major quantitative trait locus (QTL). The causal nucleotide polymorphism caused a short-period phenotype under light and severely dampened rhythm generation in darkness, and entrainment alterations resulted. We found that ELF3-Sha protein failed to properly localize to the nucleus, and its ability to accumulate in darkness was compromised. Evidence was provided that the ELF3-Sha allele originated in Central Asia. Collectively, we showed that ELF3 protein plays a vital role in defining its light-repressor action in the circadian clock and that its functional abilities are largely dependent on its cellular localization.

Highlights

The rotation of the earth leads to environmental changes in ambient light and temperature that define a 24-hr cycle
We identified that the circadian abnormalities in EARLY FLOWERING3 (ELF3)-Sha are associated to cellular localization defects of ELF3 protein that results in an inability to properly function under light and in darkness
A significant shift for shortened free-running periodicity of CCR2 after thermal entrainment was observed for the parental lines, as well as Recombinant Inbred Lines (RILs) (Figure 1A–C; Table 1)

Summary

Introduction

The rotation of the earth leads to environmental changes in ambient light and temperature that define a 24-hr cycle. During these diurnal cycles, light is correlated with warmth, while darkness is correlated with coolness. To ensure fitness in response to such regular environmental oscillations, many organisms have evolved an internal timing mechanism to predict these cyclic environmental cues, and this is termed the circadian clock. This internal clock synchronizes major developmental and physiological processes. The coordination of molecular and physiological processes with the external environment provides an adaptive advantage under diverse climatic conditions (Dodd et al, 2005)

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