Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
Proc Natl Acad Sci U S A. 2010 Jul 20;107(29):13171-6. doi: 10.1073/pnas.1001429107. Epub 2010 Jul 1.
Circadian oscillators provide rhythmic temporal cues for a range of biological processes in plants and animals, enabling anticipation of the day/night cycle and enhancing fitness-associated traits. We have used engineering models to understand the control principles of a plant's response to seasonal variation. We show that the seasonal changes in the timing of circadian outputs require light regulation via feed-forward loops, combining rapid light-signaling pathways with entrained circadian oscillators. Linear time-invariant models of circadian rhythms were computed for 3,503 circadian-regulated genes and for the concentration of cytosolic-free calcium to quantify the magnitude and timing of regulation by circadian oscillators and light-signaling pathways. Bioinformatic and experimental analysis show that rapid light-induced regulation of circadian outputs is associated with seasonal rephasing of the output rhythm. We identify that external coincidence is required for rephasing of multiple output rhythms, and is therefore important in general phase control in addition to specific photoperiod-dependent processes such as flowering and hypocotyl elongation. Our findings uncover a fundamental design principle of circadian regulation, and identify the importance of rapid light-signaling pathways in temporal control.
生物钟振荡器为动植物的各种生物过程提供了有节奏的时间线索，使它们能够预测昼夜周期，并增强与适应能力相关的特征。我们已经使用工程模型来了解植物对季节性变化的反应的控制原理。我们表明，生物钟输出的时间变化需要通过前馈回路进行光调节，将快速的光信号通路与被调节的生物钟振荡器结合起来。为了量化生物钟振荡器和光信号通路对 3503 个生物钟调节基因和胞质游离钙浓度的调节幅度和时间，我们计算了生物钟节律的线性时不变模型。生物信息学和实验分析表明，快速光诱导的生物钟输出调节与输出节律的季节性重新同步有关。我们确定了外部巧合是多个输出节律重新同步所必需的，因此除了开花和下胚轴伸长等特定光周期依赖性过程之外，它在一般相位控制中也很重要。我们的发现揭示了生物钟调节的基本设计原则，并确定了快速光信号通路在时间控制中的重要性。
