Role of aquaporins in plant water relations

自发现水通道蛋白（水通道蛋白）以来，人们开始认识到它们在植物水分关系中的关键作用。在植物中，影响、调节和协调水通道蛋白功能的因素和过程有待进一步研究。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旨在提供有关水通道蛋白介导的运输在植物水分关系中的作用的研究。在一项研究中，我们将研究不同叶片组织中的细胞水关系，以检验水细胞运输特性在叶片组织中反映其功能差异的假设，这些差异是由单个水通道蛋白的表达水平反映的。另一项研究将利用过表达一种主要水通道蛋白的转基因杂交杨树，研究水通道蛋白在植物根和叶水分运输过程的协调和整合中的作用。我们还将使用过表达水通道蛋白的基因转化真菌来检验真菌水通道蛋白有助于菌根植物根和叶水分运输的假设。以接种双色拉卡菌根真菌的白杨（Populus tremuloides）为实验材料，研究了菌根关联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参与了根对菌根定植的水力响应。内生真菌对植物水分关系的影响也将以最近发现的根内生真菌Piriformospora indica定殖的拟南芥为研究对象。这种真菌由于其促进植物生长和保护胁迫的特性而引起了广泛的关注。我们将检验真菌通过改变水通道蛋白的功能在植物中引发这些反应的假设。拟议的研究将填补我们在植物水分关系知识方面的重要空白，这对旨在提高生长和产量的方法和实践的发展至关重要。

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.