BIG Regulates the Circadian Clock and Development

由于人口增长和环境变化，迫切需要了解调节作物产量的基本生物学。我们最近发现，一种名为BIG的蛋白质参与了植物发育和植物报时能力的调节。我们将解决BIG如何对植物的生长产生如此深远的影响。我们将通过研究植物生物钟的调节，以及BIG在生物钟中的作用与激素调节植物发育的途径之间的关系来实现这一点。小麦、大麦、番茄和许多其他作物的育种者通过传统育种改变了与生物钟有关的基因，以提高产量。我们感兴趣的是确定植物确保细胞过程在一天中正确时间发生的细胞机制。例如，就在黎明前，植物准备光合机制，为太阳的升起做好准备，而在晚上，与储存糖的分解有关的过程，为在黑夜中生存提供能量。生物事件的正确时间由内部生物钟调节，在概念上类似于调节人类睡眠和觉醒周期的生物钟。在植物中，生物钟控制着许多活动，包括花朵的开放和关闭，基因活性的变化以及淀粉产生和降解的时间。生物钟存在于每个细胞中，由在白天或夜晚的特定时间活跃的基因电路组成。这些基因相互调节，形成一个振荡器，可以被概念化为一个分子手表。生物钟通常被认为是24小时的生物钟，但这并不严格正确，拟南芥和其他生物的生物钟周期是可变的。我们已经发现，细胞内的糖加快了生物钟，而一种常见的代谢物烟酰胺使生物钟运行得更慢。我们的研究已经确定了一种蛋白质，它是正确控制昼夜节律速度所必需的，这种蛋白质被称为BIG。我们将发现哪些生物钟基因改变行为以响应BIG功能的改变，并确定与BIG相互作用以调节昼夜节律振荡器速度的蛋白质。我们将发现BIG是否参与单独对烟酰胺的反应，或者也参与由糖，光信号和激素引起的昼夜节律速度的变化。我们将通过研究不同长度的光暗周期中基因表达和叶片运动的时间来发现BIG是否影响植物生物钟对黎明时间变化的反应能力。我们将利用这些信息来研究BIG如何有助于激素信号传导和发育调控。我们将确定BIG是否影响植物发育的生物钟和激素控制，因为这两个过程密切相关，或者因为BIG在不同的过程中具有不同的功能。这些研究将开始，以解决如何大，一个主要的调节器的许多方面的功能，一个植物，发挥其影响。这项工作将在适合实验室研究的简单植物中进行，最终目标是了解作物植物中重要的生物反应如何控制作物的主要性状。

Due to population growth and changing environments there is an urgent need to understand the basic biology that regulates the yield of crop plants. We have recently discovered that a protein called BIG is involved in the regulation of plant development and the ability of plants to tell the time. We will resolve how BIG exerts such profound effects on the growth of plants. We will do this by investigating the regulation of circadian clocks in plants, and the relationship between the role of BIG in the circadian clock with pathways by which hormones regulate plant development. Breeders of wheat, barley, tomato and many other crops have through traditional breeding altered the genes involved in the circadian clock to increase productivity. We are interested in identifying the cellular mechanisms by which plants ensure that cellular processes occur at the correct time of day. For example, just before dawn plants prepare the photosynthetic machinery to be ready for the rising of the sun, whereas at night, process involved in the breakdown of storage sugars to provide energy for surviving the dark of the night come to the fore. The correct timing of biological events is regulated by internal circadian clocks, similar in concept to those that regulate human sleep and wake cycles. In plants, circadian clocks control many activities including the opening and closing of flowers, changes in gene activity and the timing of starch production and degradation. The circadian clock, present in every cell, is made of circuits of genes that are active at specific times of the day or night. These genes regulate each other to form an oscillator that can be conceptualised as a molecular watch. The circadian clock is popularly considered a 24 h clock, but this is not strictly correct, the period of the circadian clock of Arabidopsis, and other organisms is variable. We have discovered that cellular sugars speed up the circadian clock and a common metabolite, nicotinamide, makes the clock run more slowly. Our studies have identified a protein that is required for the correct control of circadian speed, this protein is called BIG. We will discover which circadian clock genes change behaviour in response to altered function of BIG and identify proteins that interact with BIG to regulate the speed of the circadian oscillator. We will discover if BIG is involved in the response to nicotinamide alone, or also participates in changes in circadian speed caused by sugars, light signals and hormones. We will discover if BIG affects the ability of plant circadian clocks to respond to the changing time of dawn by examining the timing of gene expression and leaf movements in light and dark cycles of different lengths. We will use this information to investigate how BIG also contributes to hormonal signalling and the regulation of development. We will determine if BIG affects both the circadian clock and hormonal control of plant development because these two processes are closely related, or because BIG has separate functions in different processes. These studies will begin to resolve how BIG, a major regulator of many aspects of the functioning of a plant, exerts its effects. This work will be performed in a simple plant suited to laboratory studies, with the ultimate goal of understanding how important biological responses in crop plants control the major traits of the crops.