Collaborative Research: Testing the Munch Hypothesis: Hydraulics of Phloem Transport in Vines and Trees

项目名称：合作研究：验证蒙克假说：葡萄和树木韧皮部运输的水力学主要研究者：Holbrook，诺埃尔M.，和Michael KnoblauchNSF项目编号：1021779和1022106韧皮部，一种允许植物将光合作用产物从合成或储存场所运输到呼吸和/或生长中利用场所的细胞管道网络，是植物整合光合作用和生长的主要途径。韧皮部运输被假设为被驱动，但这是否发生通过连续的细胞质途径是未知的。在这个项目中，测量韧皮部运输速率，膨压和水力传导率的解剖数据的基础上，将被用来调查葡萄树和树木的韧皮部的水力功能。一个主要的目标是确定是否在膨压梯度足以驱动运输在观察到的速率实际存在，从而支持一个连续的细胞内途径的假设;或者韧皮部可以分割成离散的单位，溶质被积极重新加载。这个问题的解决是至关重要的理解植物内碳水化合物运动的水力约束。鉴于韧皮部在连接光合作用和生长中的核心作用，全面了解韧皮部运输对于预测和潜在地改变植物对资源可用性和/或压力气候条件的反应是必不可少的。将积极征聘妇女和任职人数不足的少数民族担任这些职位。对K-12和公共教育的贡献包括阿诺德植物园游客中心的互动展览，该中心每年接待超过250，000名游客，其中包括许多学校团体。此外，还将在植物园的网站上张贴在线版本，作为“树木基础知识”系列的一部分。第二个展览的大幅面图像，伴随着教育材料，将显示在各种公共空间，开始在普尔曼，华盛顿州，随后在整个国家。

Project Title: Collaborative Research: Testing the Munch Hypothesis: Hydraulics of Phloem Transport in Vines and TreesPrincipal Investigators: Holbrook, Noel M., and Michael KnoblauchNSF Project Numbers: 1021779 and 1022106 The phloem, a network of cellular conduits that allows plants to transport the products of photosynthesis from sites of synthesis or storage to sites of utilization in respiration and/or growth, is the major pathway through which plants integrate photosynthesis and growth. Phloem transport is hypothesized to be driven osmotically, but whether this occurs through a continuous cytoplasmic pathway is unknown. In this project, measurements of phloem transport rates, turgor pressure and hydraulic conductivity based on anatomical data will be used to investigate the hydraulic functioning of phloem in vines and trees. A major goal is to determine if the gradients in turgor pressure sufficient to drive transport at observed rates actually exist, thus supporting the hypothesis of a continuous intracellular pathway; alternatively the phloem could be segmented into discrete units into which solutes are actively re-loaded. Resolution of this issue is critical for understanding the hydraulic constraints underlying the movement of carbohydrates within plants. Given the central role of the phloem in linking photosynthesis and growth, a comprehensive understanding of phloem transport is essential for predicting and potentially modifying how plants respond to altered resource availability and/or stressful climatic conditions.This collaborative project will support both a graduate student and a postdoctoral fellow, and will provide research opportunities for undergraduates. Women and underrepresented minorities will be actively recruited for these positions. Contributions to K-12 and public education include an interactive exhibit for the Arnold Arboretum's visitor center, which receives over 250,000 visitors per year, including many school groups. In addition, an on-line version will be posted on the Arboretum's web site as part of the "Tree Basics" series. A second exhibit of large-format images, accompanied by educational materials, will be displayed in a variety of public spaces, beginning in Pullman, WA and subsequently throughout the state.