Tissue specific aquaporin expression for seedling water stress resistance

这个植物科学项目结合了细胞生物学和植物生理学来了解种子在发芽和发芽后的幼苗生长过程中如何吸收水分，以及我们如何控制这一过程来开发能够在水分胁迫条件下发芽和建立的作物。种子萌发后植物组织的快速扩张对作物成活率和植株均匀性至关重要，并直接影响作物周期结束时的品质和产量。因此，早熟是作物改良的重要目标。大多数细胞（包括种子细胞）通过称为水通道蛋白（AQP）的蛋白质水通道吸收水分。我们对AQP在植物根和叶中的结构和功能了解甚多，但对其在种子萌发和萌发后幼苗生长中的作用知之甚少。我们的项目直接解决了这个问题。AQP存在于不同的细胞膜上，水分摄入通常由外细胞膜（质膜）上的AQP控制。值得注意的是，我们发现在种子中，通常存在于质膜上的AQP直到种子发芽后才产生。那么在发芽过程中是什么在控制水分的进入呢？我们发现通常存在于液泡膜上的AQP在种子成熟和萌发过程中也存在于质膜上。因此，种子似乎有一种独特的方式通过向质膜发送细胞质AQP来调节水分摄入。我们还发现，经过修饰产生大量种子AQP的植物能够在水分胁迫条件下发芽和生长，表现明显优于野生型植物。因此，我们假设种子AQP是种子中水流和幼苗早期生长的主要控制者，可以用来产生更好地应对干旱条件的植物。我们的项目旨在通过研究细胞质AQP靶向质膜的方式来了解AQP的作用。我们还建议在一系列水分胁迫条件下操纵种子细胞质膜上AQP的数量和类型，并将其与种子发芽能力和萌发后幼苗生长活力联系起来。我们将在模式植物拟南芥中进行基础实验，但与此同时，我们也将在甘蓝中进行试点实验，这种作物的协调发芽和早期活力对最终产量有直接的重大影响。在项目结束时，我们的目标是提高对萌发和早期苗木生长过程中AQP调节的理解，并建立控制AQP的策略，以最大限度地提高早期活力和抗水胁迫能力。

This plant science project combines cell biology and plant physiology to understand how seeds take up water during germination and post-germination seedling growth and how we can control this process to develop crops that can germinate and establish in water stress conditions. Rapid plant tissue expansion after seed germination is crucial for crop establishment and plant uniformity and it directly impacts on quality and yield at the end of the crop cycle. For these reasons early vigour is an important target for crop improvement. Most cells (including seed cells) take up water through protein water channels called aquaporins (AQP). While a lot is known about AQP structure and function in plant roots and leaves, very little is known about their role in seed germination and post-germination seedling growth. Our project directly addresses this question. AQP exist on different cellular membranes and water intake is usually controlled by AQP on the outer cell membrane (the plasma membrane). Remarkably, we have found that in seeds the AQP that are normally present on the plasma membrane are NOT produced until AFTER the seed has germinated. So what is controlling water entry during germination? We have discovered that AQP that normally reside on the membrane of the vacuole (the tonoplast) are also found at the plasma membrane during seed maturation and germination. Therefore it seems that seeds have a unique way of regulating water intake by sending tonoplast AQP to the plasma membrane.We have also discovered that plants modified to produce very high amounts of seed AQP are able to germinate and grow in conditions of water stress, performing significantly better than wild-type plants. Therefore we hypothesise that seed AQP are major controllers of water flow in seeds and early seedling growth that can be used to generate plants that cope better with drought conditions.Our project aims at understanding the role of AQP by studying the way the tonoplast AQP are targeted to the plasma membrane. We also propose to manipulate both the amount and type of AQP present on the seed cells' plasma membrane and correlate it with the ability of seeds to germinate and the vigour of post-germination seedling growth using a range of water stress conditions. We will perform the basic experiments in the model plant Arabidopsis but, in parallel we will also perform pilot experiments in Brassica oleracea, a crop for which co-ordinated germination and early vigour can have a direct, major impact on final yield. By the end of the project we aim to have improved understanding of the regulation of AQP during germination and early sedling growth and to have established strategies to manipulate AQP in order to maximise early vigour and water stress resistance.