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

大多数生物都是用来测量时间的。我们熟悉人类的“生物钟”，它作为一个内部时钟，让我们以固定的时间间隔睡觉和醒来。特别是，当我们跨越时区，遇到时差时，我们会体验到时钟被打乱的生理影响。植物也测量时间，并使用这些信息来测量季节的长度和控制开花。许多植物行为只发生在一天中的特定时间，例如睡莲花只在一天的中间开放，并在黄昏前很久关闭。我们最近发现，有功能时钟的植物比没有工作时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，细胞中的糖含量是有节奏的变化。白天，植物利用来自阳光的能量，通过光合作用制造糖。在夜间，细胞的含糖量很低，因为没有光合作用。我们的发现表明，糖调节生物钟的行为表明，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分所需的基因之一。这就是巨人茶(Gi)，一种已知的属于生物钟的基因。我们现在想要了解GI如何对糖做出反应，以及这如何影响时钟的功能。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除了在糖调节生物钟的作用之外，是否还在糖介导的发育和基因活性的变化中发挥作用。这将发现GI是否是一般血糖感知机制的一部分。我们希望通过生物钟找到其他对糖分感知重要的基因。我们将寻找生物钟的其他基因对糖分感觉的影响。我们还将调查已知在其他糖感途径中起作用的其他基因是否也对时钟的糖感有影响。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GI基因在影响植物含糖量的环境中的生长和生理学来实现这一点。对GI和糖感应的生理作用的了解是规划如何生产生长更快、更健康、更大的作物或生产新产品(如生物燃料)的关键步骤。

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.