The Role of GIGANTEA in mediating metabolic input in to the Arabidopsis circadian clock

大多数生物都是测量时间的。我们熟悉我们的人体“生物钟”，它作为一个内部手表，让我们在固定的时间间隔睡觉和醒来。特别是，当我们穿越时区并时差时，我们会体验到生物钟中断的生理影响。植物也测量时间，并利用这些信息来测量季节的长度和控制开花。许多植物的行为只发生在一天中的特定时间，例如睡莲花只在中午开放，在黄昏前很久就关闭了。我们最近发现，有生物钟的植物比没有生物钟的植物生长得更快。植物中的计时器存在于每个细胞中，被称为生物钟。我们有新的数据表明，糖可以调节生物钟的行为。这一点很重要，因为在植物中，细胞中糖的含量有节奏地变化。在白天，利用阳光的能量，植物通过光合作用制造糖。在夜间，由于没有光合作用，细胞中的糖含量很低。我们发现糖调节生物钟的行为，这表明植物的新陈代谢调节其他活动的日常节奏的机制。我们已经确定了植物生物钟感知糖所需的基因之一。这就是GIGANTEA（GI），一种已知是生物钟一部分的基因。我们现在想了解GI如何对糖做出反应，以及这如何影响生物钟的功能。我们将测量糖如何影响GI基因以及GI蛋白与其他蛋白质之间的相互作用。糖不仅调节生物钟。糖影响植物的发育并调节许多基因。我们将发现GI是否在糖介导的发育和基因活性变化中发挥作用，以及它在糖调节生物钟中的作用。这将发现GI是否是一般糖感测机制的一部分。我们希望找到其他基因对昼夜节律钟的糖传感很重要。我们将寻找其他基因的昼夜节律对糖传感的影响。我们还将研究其他已知在其他糖传感途径中发挥作用的基因是否也对生物钟的糖传感产生影响。我们项目的一个主要目标是找出为什么糖会影响植物的生物钟。我们将通过研究在影响植物糖含量的环境中具有遗传操纵水平的GI基因的植物的生长和生理来做到这一点。对GI和糖传感的生理作用的理解是规划如何生产生长更快，更健康，更大或生产新产品（如生物燃料）的作物的重要一步。

Most living organisms measure time. We are familiar with our human 'body clock' which acts as an internal watch allowing us to sleep and wake up at regular time intervals. In particular, we experience the physiological effects of disruption of the clock when we cross time zones and get jet-lag. Plants also measure time and use this information to measure the length of the seasons and to control flowering. Many plant behaviours only occur at specific times of the day, for example water lily flowers are only open in the middle of the day and close long before dusk. We have recently found that plants with a functional clock grow faster than plants that do not have a working clock. The time-keeper in plants is present in every cell and is known as a circadian clock. We have new data that demonstrate that sugar can regulate the behaviour of the circadian clock. This is important because in plants, there are rhythmic changes in the content of sugar in the cells. In the day, using the energy from sunlight, plants make sugar by photosynthesis. At night the sugar content of cells is low because there is no photosynthesis. Our finding that sugar regulates the behaviour of the circadian clock suggests a mechanism by which the metabolism of plants regulates daily rhythms of other activities. We have identified one of the genes required for the sensing of sugar by the plant circadian clock. This is GIGANTEA (GI), a gene already known to be part of the clock. We now want to understand how GI responds to sugar and how this affects the function of the clock. We will measure how sugar affects the GI gene and interactions between the GI protein with other proteins. Sugar does not only regulate the circadian clock. Sugar affects the development of the plant and regulates many genes. We will find out if GI has a role in sugar-mediated changes in development and gene activity, in addition to its role in sugar regulation of the clock. This will find out if GI is part of a general sugar sensing mechanism. We hope to find other genes important for sugar sensing by the circadian clock. We will look for effects of other genes of the circadian clock on sugar sensing. We also will investigate whether other genes already known to have a role in other sugar-sensing pathways also have an effect on sugar sensing by the clock. A major goal of our project is to find out why sugar affects the plant circadian clock. We will do this by studying the growth and physiology of plants with genetically-manipulated levels of the GI gene in environments that affect the sugar content of the plant. This understanding of the physiological role of GI and sugar sensing is an essential step in planning how to produce crop plants that grow faster, are healthier, larger or produce new products, such as biofuels.