RUI: Adaptive Significance of Circadian Rhythms in StomatalFunction and Photosynthesis

几乎所有的生物——从人类到豆类植物——都表现出“昼夜节律”，即以24小时为周期的各种功能的节律波动。植物也有这样的节奏。例如，豆类植物在白天将叶子水平放置（以便捕捉阳光），但在晚上将叶子垂直放置在茎上，即使植物保持在恒定的光线下，它们也会继续这种有节奏的运动，没有任何线索表明它是一天中的什么时候。没有人知道这种有节奏的叶子运动是否对植物有好处，但部分原因是没有人知道叶子沿着茎折叠会给植物带来什么好处，不管这种折叠是否有节奏。研究人员将研究有节奏的运动对植物可能带来的好处，但在一个比叶子运动更容易理解的过程中。叶子通过被称为气孔的小气孔与空气相连，这些气孔可以打开和关闭。众所周知，当植物可以进行光合作用时（例如，白天），气孔会打开，而当光合作用不可能发生时（例如，晚上），气孔会关闭。除了这些对环境变化的反应外，气孔也根据一个大约24小时周期的内部时钟打开和关闭：它们有昼夜节律。到目前为止，还没有人试图系统地了解昼夜节律如何影响气孔。这个问题对基础科学很重要，主要有两个原因。首先，如果不了解节律因素，对气孔反应的理解就不可能真正完整。其次，一些实验室正致力于了解从人类到单细胞植物等生物体中驱动昼夜节律的时钟的基本工作原理，任何昼夜节律研究都有希望揭示这个极其重要且难以捉摸的基本问题。也有潜在的实际效益，因为对气孔的研究总是具有农业应用的潜力。气孔控制着植物利用水分的速度，而水分利用是任何作物的一个极其重要的特征，尤其是在全球变化的时代，育种和选择能够在变化的环境中生存的植物变得非常重要。最后，这项研究将在本科院校进行，并将广泛涉及本科生，为他们的科学事业提供一个宝贵的机会来教育和激励他们。

Practically all organisms-from human beings to bean plants- exhibit "circadian rhythms," rhythmic fluctuations in all kinds functions that have a period of about twenty-four hours. Plants have such rhythms, too. Bean plants, for example, hold their leaves horizontally during the day (in a position to catch the sun), but hold them vertically along the stem at night, and they will continue this rhythmic movement even if plants are kept in constant light, with no clues as to what time of day it is. No one knows whether this rhythmic leaf movement does the plant any good, but that is partly because no one knows what benefit the plant might get from having its leaves folded along the stem, whether rhythmically or not. The investigators will examine the possible benefit to the plant of a rhythmic movement, but in a process whose function is much better understood than leaf movements. Leaves are connected to the air by small pores called stomata, and these pores can open and close. It is well known that the stomata open when the plants can photosynthesize (during the day, for example), and that they close when photosynthesis is unlikely to take place (at night, for example). In addition to responses like these to environmental changes, stomata also open and close according to an internal clock with a period of about twenty-four hours: they have circadian rhythms. Until now, no one has tried systematically to understand how circadian rhythms affect stomata. This question is important to basic science for two major reasons. First, understanding of stomatal responses cannot be really complete without an understanding of the rhythmic element. Second, several laboratories are concerned with understanding the basic working of the clock that drives circadian rhythms in organisms ranging from humans to single-celled plants, and any circadian research has some promise for shedding light on this extremely important and elusive basic question. There are also potential practical benefits, because research on stomata always has potential for agricultural applications. Stomata control the rate at which plants use water, and water use is an extremely important characteristic of any crop, particularly in an era of global change when breeding and selecting of plants that can survive a changed environment take on immense importance. Finally, the research will be done at an undergraduate institution and will involve undergraduate students extensively, providing a valuable opportunity to educate and inspire them for the career in science.