Role of aquaporins in plant water relations

自从水通道蛋白(Aquaporins)被发现以来，人们开始认识到它们在植物水分关系中的关键作用。现在需要做出重大努力来了解影响、调节和协调植物中水通道蛋白功能的因素和过程。拟议项目的主要目标是发展有关水通道蛋白在植物水流调节中的作用的知识。拟议的项目包括一系列研究，旨在增进关于水通道蛋白介导的运输在植物水分关系中的作用的知识。在一项研究中，我们将研究不同叶组织中细胞的水分关系，以检验这样一种假设，即叶组织中水细胞的运输特性不同，反映了它们的功能差异，这些差异反映在单个水通道蛋白的表达水平上。另一项研究将利用过量表达主要水通道蛋白的转基因杂交杨树来研究水通道蛋白在植物根和叶水分运输过程中的协调和整合功能。我们还将使用过度表达水通道蛋白的转基因真菌来检验真菌水通道蛋白有助于菌根植物根和叶的水分运输的假设。在接种了漆树菌根真菌的杨树上，还将研究菌根联合对根和叶水分运输的影响，以研究茉莉酸信号通路通过水通道蛋白表达的变化而参与根对菌根定植的水力反应的假说。内生真菌对植物水分关系的影响也将与最近发现的根内生植物印度梨形孢子定植拟南芥进行研究。这种真菌因其促进植物生长和保护逆境的特性而引起了人们的广泛兴趣。我们将检验这一假说，即真菌通过改变水通道蛋白的功能在植物中触发这些反应。拟议的研究将填补我们对植物水分关系知识的重要空白，这对发展旨在提高生长和产量的方法和实践至关重要。

Since the discovery of water channel proteins (aquaporins), recognition of their pivotal role in plant water relations has begun to emerge. Major effort is now required to learn about the factors and processes which affect, regulate and coordinate the functions of aquaporins in plants. The principal objective of the proposed project is to develop knowledge concerning the role of aquaporins in water flow regulation in plants. The proposed project consists of the series of studies aimed at contributing knowledge concerning the role of the aquaporin-mediated transport in plant water relations. In one study, we will investigate cell water relations in different leaf tissues to examine the hypothesis that the water cell transport properties differ in leaf tissues reflecting their functional differences and that these differences are reflected by the expression levels of individual aquaporins. Another study will be carried out using genetically-transformed hybrid poplars, which overexpress a major aquaporin, to study the function of aquaporins in the coordination and integration of root and leaf water transport processes in plants. We will also use genetically-transformed fungi which overexpress aquaporins to examine the hypothesis that the fungal aquaporins contribute to root and leaf water transport of mycorrhizal plants. Effects of mycorrhizal associations on root and leaf water transport will be also carried out in aspen (Populus tremuloides) inoculated with Laccaria bicolor mycorrhizal fungus to study the hypothesis that jasmonic acid-signalling pathway is involved in the root hydraulic responses to mycorrhizal colonization through changes in aquaporin expression. The effects of endophytic fungi on plant water relations will be also conducted with Arabidopsis thaliana colonized by a recently discovered root endophyte Piriformospora indica. This fungus has generated extensive interest due to its plant growth-promoting and stress-protecting properties. We will examine the hypothesis that the fungus triggers triggers these responses in plants by altering the function of aquaporins. The proposed studies will fill important gaps in our knowledge of plant water relations which is crucial to the development of methods and practices aimed at growth and yield improvement.