Mechanisms and functions of photosynthetic entrainment of the Arabidopsis circadian clock

生物钟是一个24小时计时装置，控制着每天的活动节奏。在植物中，生物钟调节光合作用、生长以及新陈代谢和发育的大多数方面，以赋予竞争优势。我们已经确定了一种新的途径，在这种途径中，光合作用产生的糖（植物的决定性代谢途径）调节植物生物钟的时间，以确保植物的节奏与当地的昼夜周期正确匹配。这个新发现的过程定义了代谢黎明。我们现在希望了解代谢黎明发生的机制，并理解为什么生物钟是由光合作用产生的糖来调节的。我们将进行实验研究，旨在了解当植物无法对光合作用产生的糖做出反应时，对生物钟的影响。我们将通过在阻止正常光信号通路运作的条件和突变植物中进行实验，发现每日糖的循环是否足以确保昼夜节律时钟的正确定时。使用类似的方法来操纵光合作用，我们将研究当光合作用被抑制时，昼夜节律与当地昼夜环境的匹配程度。这将告知光合作用对整个生物钟功能的贡献。我们将与日本的研究人员合作，创建糖对生物钟调节的数学描述，以及生物钟调节糖丰度的反向过程。数学分析将确定生物钟对糖的反应主要是为了提高生物钟的性能还是优化植物的碳利用。数学模型的预测将为实验测试提供新的途径，而这不是单凭直觉就能得到的。我们将进行实验研究，探讨糖调节生物钟的机制。我们研究了已知参与植物对糖的其他反应的基因是否也参与生物钟的调节。我们将确定糖是否通过引起dna结合蛋白的化学修饰来调节基因表达。我们将进行实验来确定钙离子和钙结合蛋白是否参与糖对昼夜节律系统的调节。我们将抑制特定细胞类型的光合作用，以确定糖信号是否通过植物扩散来调节邻近细胞的生物钟。为了完成这项工作，我们组建了一个研究团队，他们精通昼夜节律、dna结合蛋白的化学修饰、光合作用和数学。

The circadian clock is a 24 h timing device that controls daily rhythms of activity. In plants, the circadian clock regulates photosynthesis, growth and most aspects of metabolism and development to confer a competitive advantage. We have identified a new pathway in which the sugars made by photosynthesis, the defining metabolic pathway of plants, adjust the timing of the plant circadian clock to ensure that the rhythms of the plant are correctly matched to the local day/night cycle. This newly identified process defines a metabolic dawn. We wish now to understand the machinery by which the metabolic dawn occurs and understand why the circadian clock is adjusted by the sugars made by photosynthesis.We will perform experimental studies aimed at understanding the consequence for the circadian clock when the plant is prevented from responding to sugars produced by photosynthesis. We will find out if the daily cycle of sugars is sufficient alone to ensure correct timing of the circadian clock by perform experiments in conditions and mutant plants which prevent the normal light signalling pathways from operating. Using similar approaches to manipulate photosynthesis, we will study how well circadian rhythms are matched to the local day and night environment when photosynthesis is inhibited. This will inform about the contribution of photosynthetic entrainment to the functioning of the entire circadian clock. We will partner with researchers in Japan to create mathematical descriptions of the regulation of the circadian clock by sugars and the reverse process in which the circadian clock regulates the abundance of sugars. The mathematical analyses will determine if the response of the circadian clock to sugar is primarily to improve circadian clock performance or optimizes plant carbon usage. The predictions of the mathematical models will provide new avenues for experimental testing that would not be arrived at by intuition alone. We will perform experimental studies to investigate the machinery by which sugars regulate the circadian clock. We investigate whether the genes already known to be involved in other responses of plants to sugars are also involved in the regulation of the circadian clock. We will determine whether sugars regulate gene expression by causing chemical modifications of DNA-binding proteins. We will perform experiments to determine if the calcium ion and calcium-binding proteins are involved in the regulation of the circadian system by sugars. We will inhibit photosynthesis in specific cell-types to determine if sugar signals diffuse through the plant to regulate the circadian clock in neighbouring cells.To perform this work we have formed a team of researchers with skills in circadian rhythms, chemical modification of DNA-binding proteins, photosynthesis and mathematics.