RUI: Regulation of Water Uptake in Tank Bromeliads

RUI：水箱凤梨科植物吸水的调节

• 批准号: 1258499
• 负责人: Gretchen North
• 金额: $ 21.23万
• 依托单位: Occidental College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1258499&HistoricalAwards=false
• 关键词: RUI; Regulation; Water; Uptake; Tank

Tank bromeliads are plants that grow on trees in the forest canopy in the Neotropics, deriving sustenance from the water and nutrients collected in the tanks formed at the base of their leaves. In addition to the ecological importance of tank bromeliads due to the rich communities sustained in and by the tank water, they are excellent case studies for investigating the role of environmental variables such as light in governing leaf water uptake. Many bromeliad species can occur at several positions in the canopy, thus even a single host tree can provide a range of plants from different light exposures. The capacity of leaves to transport water, or leaf hydraulic conductance, can determine a plant's ability to succeed in its environment, and light can determine that capacity due to long-term effects on leaf anatomy and morphology and short-term effects on leaf physiology. Because tank bromeliads virtually lack absorptive roots and stems, they also provide excellent models in which to investigate external and internal regulators of leaf hydraulic conductance. The relatively simple strap-shape of the leaves as well as their parallel venation facilitate measurement and modeling of leaf hydraulic conductance for bromeliads, and their use of tanks as reservoirs allows manipulation of the water supply to investigate the effects of environmental and internal regulators. Specifically, light and pH are known to affect leaf hydraulic conductance at least in part via their effects on aquaporins, proteins that regulate water movement across membranes. This research is truly integrative in that the regulation of leaf hydraulic conductance will be assessed in the field at the level of plant responses to light variation within the forest canopy as well as in the laboratory, using experimental manipulations of light, tank-water pH, and aquaporin inhibitors. Aquaporin gene expression in leaves from different light exposures and in different leaf regions will also be measured and compared. For plants in both field and laboratory, anatomical and morphological traits will be investigated and incorporated into a model of leaf hydraulic conductance that will be further informed and tested by microscopic examination of the pathways indicated by tracer and diagnostic staining. Because the leaves of tank bromeliads are the organs of both supply and demand, understanding how their leaf hydraulic conductance is regulated is fundamental to understanding their ecological function and how they might respond to changes that are rapidly occurring in tropical forests. The role of tank bromeliads and other plants that grow in the branches of the tropical tree canopy is predicted to become even more important as primary forest becomes more fragmented and is replaced by secondary forest.The research will be carried out entirely by the principal investigator and undergraduate students, both in the field at La Selva Biological Station in Costa Rica and in the laboratory at Occidental College. A key component of the proposed research is its use of a field station in Costa Rica, in part because Occidental College's location in Los Angeles attracts many students with personal and intellectual ties to Latin America. One major goal of the proposed research is to strengthen those ties and to develop an international experience for undergraduates that will demonstrate the role of science in understanding how people and other organisms are linked by global processes such as water use and changes in forest structure.

水箱凤梨科植物是生长在新热带地区森林冠层树木上的植物，从叶子基部形成的水箱中收集的水和养分中获取营养。除了由于水箱水中维持丰富的群落而使水箱凤梨科植物具有生态重要性之外，它们还是研究光等环境变量在控制叶子吸水方面的作用的绝佳案例研究。许多凤梨科植物物种可以出现在树冠的多个位置，因此即使是一棵寄主树也可以提供一系列来自不同光照的植物。叶子输送水的能力或叶子水导率可以决定植物在其环境中成功的能力，而光可以由于对叶子解剖和形态的长期影响以及对叶子生理的短期影响而决定这种能力。由于水箱凤梨科植物实际上缺乏吸收性的根和茎，因此它们还提供了研究叶片水力传导的外部和内部调节器的优秀模型。叶子相对简单的带状形状及其平行的脉络有利于凤梨科植物叶子水力传导的测量和建模，并且它们使用水箱作为水库可以控制供水以研究环境和内部调节器的影响。具体来说，已知光和 pH 值至少部分通过影响水通道蛋白（调节水跨膜运动的蛋白质）来影响叶片水力传导。这项研究是真正的综合性研究，将在现场评估植物对森林冠层内光变化的反应水平以及在实验室中使用光、水箱水 pH 值和水通道蛋白抑制剂的实验操作，评估叶片水力传导的调节。还将测量和比较不同光照下的叶子和不同叶子区域的水通道蛋白基因表达。对于田间和实验室的植物，将研究其解剖和形态特征，并将其纳入叶片水力传导模型中，通过对示踪剂和诊断染色指示的路径进行显微镜检查，进一步了解和测试该模型。由于水箱凤梨科植物的叶子是供给和需求的器官，了解它们的叶子水力传导度是如何调节的对于了解它们的生态功能以及它们如何应对热带森林中迅速发生的变化至关重要。随着原始森林变得更加破碎并被次生林取代，罐凤梨科植物和生长在热带树冠树枝上的其他植物的作用预计将变得更加重要。这项研究将完全由首席研究员和本科生在哥斯达黎加拉塞尔瓦生物站的实地和西方学院的实验室进行。拟议研究的一个关键组成部分是利用哥斯达黎加的一个实地站，部分原因是西方学院位于洛杉矶，吸引了许多与拉丁美洲有个人和智力联系的学生。拟议研究的一个主要目标是加强这些联系，并为本科生提供国际经验，展示科学在理解人类和其他生物如何通过水利用和森林结构变化等全球过程联系起来方面的作用。