Research on plant-water relations examining physiological, structural, and molecular mechanisms of plant responses to their environment

水的可获得性在维持管理生态系统和自然生态系统的健康和生产力方面发挥着重要作用。鉴于全球温度和降水模式的变化，更好地了解植物对水分胁迫的生理和分子反应变得越来越重要。气温和降水的变化对加拿大北方森林的影响预计将大于对温带和热带森林的影响。加拿大的森林可能不仅受到干旱的直接影响，而且还受到干旱带来的自然干扰(例如，火和昆虫)的影响。**水的供应往往是作物生产力和种植园树木存活的限制因素。干旱还会降低许多森林生态系统的树木生产力和存活率。一棵树的生存或死亡在一定程度上取决于它的“管道系统”的完整性，该系统位于干燥的土壤和更干燥的大气之间。**木质部是维管束植物的主要导水组织。植物的液压系统依赖于一种独特但天生不稳定的机制。当土壤干燥时，木质部中的水柱可能破裂，导致空气堵塞(血栓)。随着干旱的加剧，木材中会形成更多的血栓，直到树叶无法获得足够的水分来生存。我们将研究不同植物器官(叶、茎和根)的水力特性，以确定植物的哪个部分最容易形成血栓和丧失水力传导性。**木质部可以在远距离(红杉树超过100米)有效地运输水分和营养物质，而水通道蛋白(基于膜的水分通道)促进了细胞尺度上的水分运动。在水分进入根的木质部之前，在离开叶脉的木质部之后，它通过水孔蛋白流经活细胞。水通道是动态调节的，很可能在植物对不断变化的环境的反应中发挥重要作用。我们将研究水通道蛋白如何影响根和叶的活细胞内的水分流动，以了解它们在干旱胁迫生理中的作用。这些发现将在整个植物的背景下进行解释。这项拟议的研究将整合分子、器官、生物尺度上的水关系研究。

Water availability plays an important role in maintaining the health and productivity of both managed and natural ecosystems. In the light of global changes in temperature and precipitation patterns, it is becoming increasingly important to better understand physiological and molecular responses of plants to water stress. The impact of changes in temperature and precipitation on Canada's boreal forest is expected to be greater than on temperate and tropical forests. Forests in Canada are likely to be affected not only by direct impacts of drought but also by natural disturbances that are brought on by drought (e.g., fire and insects).**Water availability is often a limiting factor for the productivity of crops and the survival of plantation trees. Drought also reduces tree productivity and survival across many forest ecosystems. Whether a tree lives or dies in response to a drought episode depends in part on maintaining the integrity of its `plumbing system', which is positioned between the dry soil and the even dryer atmosphere. **The xylem (wood) is the principal water-conducting tissue in vascular plants. The hydraulic system of plants depends on a unique but inherently unstable mechanism. As the soil dries, water columns in the xylem may break, causing an air blockage (embolism). As drought increases, more embolism forms in the wood until leaves do not receive enough water to survive. We will study the hydraulic properties of different plant organs (leaves, stems, and roots) to determine which part of the plant is most vulnerable to embolism formation and loss of hydraulic conductivity. **While xylem allows for efficient transport of water and nutrients over long distances (over 100m in redwood trees), aquaporins (membrane-based water channels) facilitate water movement on a cellular scale. Before water enters the xylem in roots, and after it exits the xylem in leaf veins, it flows through living cells, via aquaporins. Water channels are dynamically regulated and are likely to play an important role in a plant's response to changing environments. We will study how aquaporins impact water flow in living cells of roots and leaves, in order to understand their role in drought stress physiology. Findings will be interpreted in a whole-plant context. The proposed research will integrate water relations research at the molecular, organ, organismal scales.