Shape Shifting Stomata: The Role of Geometry in Plant Cell Function

植物需要将水分从土壤中吸到嫩芽中。它们通过叶片表面被称为气孔的小而可控的气孔来蒸发水蒸气。开放的气孔使植物能够将水吸到植物的顶部，同时，它们允许二氧化碳进入叶片，用于光合作用，我们所有的食物都是通过光合作用产生的。然而，如果气孔总是打开，这将导致灾难性的水分流失，枯萎，并最终导致植物死亡。因此，植物不断调整它们的气孔，确保它们在条件好的时候足够开放，以便植物生长，但在有失去过多水分的危险时关闭。进化导致了两种主要类型的气孔：一种仅由两个细胞组成的简单形式（在大多数植物中发现）和一种由四个细胞组成的更复杂的形式。这些更复杂的气孔存在于玉米、水稻、小麦和大麦等植物中——它们是养活世界人口的最重要作物。这些植物如此成功的原因之一被认为是因为它们的气孔功能比其他植物更好，导致更少的水分流失。然而，究竟四细胞的气孔比二细胞的“好”的原因尚不清楚。我们的假设是，气孔的结构（细胞的特殊形状和/或气孔中细胞壁的机械特性）使它们成为一个更有效的控制水分流失的系统。这个项目将调查和测试这个想法。要解决牧草气孔如何更好地发挥作用的问题，需要了解气孔的力学特性，以确定哪些结构元素对气孔功能最重要。生物学家和计算科学家将共同努力创建一个四细胞气孔模型，使用模型草系统，短柄草，其中气孔生物学最近取得了重大进展，为该项目提供了重要的工具和资源。通过创建一个计算机模型，我们将能够快速探索气孔如何工作的想法。然后，我们将在实验中测试这些想法，在实验室中创造新的气孔类型并评估它们的性能。在项目期间，我们将应用新的软件工具来生成这些模型。这将使我们能够进一步验证细胞的特定形状可以对细胞的功能产生重大影响的想法。这将推进我们对生物学的基本理解，并为气孔的工作原理提供新的见解：叶片上不同气孔之间表面上微小的形状变化，实际上对气孔控制水分流失的能力有很大的影响吗？作为这项工作的结果，我们将确定是什么使得四细胞气孔比两细胞气孔更好，回答了植物生物学中一个长期存在的问题，并为作物育种者提供了潜在的信息，这些育种者希望提高作物在干旱下的生存能力——这是英国和世界农业面临的一个主要挑战。

Plants need to draw water up from the soil to the shoots. They do this by losing water vapour via small, controllable pores on the leaf surface, termed stomata. Open stomata allow plants to pull water up to the top of the plant and, at the same time, they allow carbon dioxide into the leaf where it is used for photosynthesis, the process by which all our food is made. However, if stomata were always open this would lead to catastrophic water loss, wilting, and eventual death of the plant. Therefore plants continually adjust their stomata, making sure that they are open enough to allow the plant to grow when conditions are good, but closed when there is the danger of losing too much water. Evolution has led to two main types of stomata: a simple form composed of just two cells (found in the majority of plants) and a more complex form composed of four cells. These more complex stomata are found in plants such as maize, rice, wheat and barley- the most important crops for feeding the world. One of the reasons why these plants are so successful is thought to be because their stomata function better than those found in other plants, leading to less water loss. However, exactly how the four-celled stomata are "better" than the two-celled type is unclear. Our hypothesis is that it is the structure of the stomata (both the special shape of the cells and/or the mechanical properties of the cell walls in the stomata) that make them a more efficient system for controlling water loss. This project will investigate and test this idea. To resolve the question of how grass stomata can perform better will involve understanding the mechanical properties of stomata to identify which elements of the structure are most important for stomatal function. Biologists and computational scientists will work together to create a model of the four-celled stomata, using a model grass system, brachypodium, in which significant advances in stomatal biology have recently been made, providing important tools and resources for this project.By creating a computer model we will be able to rapidly explore ideas on how the stomata work. We will then test these ideas experimentally, creating new types of stomata in the laboratory and evaluating their performance. During the project we will apply new software tools to generate these models. This will allow us to additionally test the idea that the specific shape of a cell can have a major outcome on what a cell does. This will both advance our fundamental understanding of biology and provide a new insight into how stomata work: do apparently minor changes in shape between different stomata on a leaf actually have a large influence on how well the stomata control water loss? As a result of this work we will determine what makes four-cell stomata better than two-cell stomata, answering a long-held question in plant biology and providing information that will be of potential use to crop breeders looking to improve how well crops survive under drought- a major challenge in UK and world agriculture.