James Allan B, Monreal José A, Nimmo Gillian A, Kelly Ciarán L, Herzyk Pawel, Jenkins Gareth I, Nimmo Hugh G
Division of Molecular and Cellular Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
Science. 2008 Dec 19;322(5909):1832-5. doi: 10.1126/science.1161403.
The circadian oscillator in eukaryotes consists of several interlocking feedback loops through which the expression of clock genes is controlled. It is generally assumed that all plant cells contain essentially identical and cell-autonomous multiloop clocks. Here, we show that the circadian clock in the roots of mature Arabidopsis plants differs markedly from that in the shoots and that the root clock is synchronized by a photosynthesis-related signal from the shoot. Two of the feedback loops of the plant circadian clock are disengaged in roots, because two key clock components, the transcription factors CCA1 and LHY, are able to inhibit gene expression in shoots but not in roots. Thus, the plant clock is organ-specific but not organ-autonomous.
真核生物中的昼夜节律振荡器由几个相互连锁的反馈环组成，通过这些反馈环来控制生物钟基因的表达。一般认为，所有植物细胞都含有基本相同的、细胞自主的多环生物钟。在此，我们表明，成熟拟南芥植株根中的生物钟与地上部分显著不同，且根生物钟由来自地上部分的一个与光合作用相关的信号同步。植物生物钟的两个反馈环在根中解耦，因为两个关键的生物钟组分，即转录因子CCA1和LHY，能够在地上部分抑制基因表达，但在根中却不能。因此，植物生物钟具有器官特异性，但并非器官自主性。
