在植物中，糖通过光合作用的生成是生物钟的一个关键代谢输出。
这项研究显示，节律性的内源糖信号能通过调控生物钟基因的表达设定拟南芥的生物钟的时间。
作者提出了“代谢黎明”这样一个概念，用来描述生物钟响应于光合作用所生成的内源性的糖的某一峰值而发生的重设。（生物谷Bioon.com）
生物谷推荐的英文摘要
Nature doi:10.1038/nature12603
Photosynthetic entrainment of the Arabidopsis thaliana circadian clock
Michael J. Haydon，Olga Mielczarek，Fiona C. Robertson，E. Hubbard& Alex A. R. Webb
Circadian clocks provide a competitive advantage in an environment that is heavily influenced by the rotation of the Earth1， 2， by driving daily rhythms in behaviour， physiology and metabolism in bacteria， fungi， plants and animals3， 4. Circadian clocks comprise transcription–translation feedback loops， which are entrained by environmental signals such as light and temperature to adjust the phase of rhythms to match the local environment3. The production of sugars by photosynthesis is a key metabolic output of the circadian clock in plants2， 5. Here we show that these rhythmic， endogenous sugar signals can entrain circadian rhythms in Arabidopsis thaliana by regulating the gene expression of circadian clock components early in the photoperiod， thus defining a ‘metabolic dawn’. By inhibiting photosynthesis， we demonstrate that endogenous oscillations in sugar levels provide metabolic feedback to the circadian oscillator through the morning-expressed gene PSEUDO-RESPONSE REGULATOR 7 (PRR7)， and we identify that prr7 mutants are insensitive to the effects of sucrose on the circadian period. Thus， photosynthesis has a marked effect on the entrainment and maintenance of robust circadian rhythms in A. thaliana， demonstrating that metabolism has a crucial role in regulation of the circadian clock.
