A modern circadian clock in the common angiosperm ancestor of monocots and eudicots

C Robertson Mcclung

doi:10.1186/1741-7007-8-55

Abstract

The circadian clock enhances fitness through temporal organization of plant gene expression, metabolism and physiology. Two recent studies, one in BMC Evolutionary Biology, demonstrate through phylogenetic analysis of the CCA1/LHY and TOC1/PRR gene families that the common ancestor of monocots and eudicots had components sufficient to construct a circadian clock consisting of multiple interlocked feedback loops.See research article http://www.biomedcentral.com/1471-2148/10/126

Highlights

The circadian clock enhances fitness through temporal organization of plant gene expression, metabolism and physiology
In the third loop, termed the ‘morning’ loop based on the time of peak mRNA accumulation of its constituents, CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) are positive regulators of two TIMING OF CAB EXPRESSION 1 (TOC1) relatives, PRR7 and PRR9, that are negative regulators of CCA1 and LHY [4,5]
Proper regulation of CCA1 and LHY requires other clock genes, including EARLY FLOWERING 4 (ELF4), which encodes a protein of unknown function, and LUX ARRHYTHMO/PHYTOCLOCK1 (LUX/PCL), which encodes a Myb domain transcription factor; these and other clock components have yet to be fully incorporated into current clock models [4,5]

Summary

Introduction

The circadian clock enhances fitness through temporal organization of plant gene expression, metabolism and physiology. Circadian clocks of taxonomic groups as diverse as plants, fungi and animals are composed of multiple interlocked feedback loops with positive and negative components [3] and many of the components of these clocks are encoded by members of gene families.

Results

Conclusion