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

项目名称：合作研究：测试蒙克假说：葡萄树和树木韧皮部运输的水学主要研究者：Holbrook， Noel M.和Michael KnoblauchNSF项目编号：1021779和1022106韧皮部是一个细胞导管网络，它允许植物将光合作用的产物从合成或储存地点运输到呼吸和/或生长的利用地点，是植物整合光合作用和生长的主要途径。假设韧皮部运输是由渗透驱动的，但这是否通过连续的细胞质途径发生尚不清楚。在本项目中，基于解剖学数据的韧皮部运输速率、膨胀压力和水力传导率的测量将用于研究葡萄藤和树木韧皮部的水力功能。一个主要的目标是确定是否存在足以以观察到的速率驱动运输的膨胀压力梯度，从而支持连续细胞内途径的假设；或者，韧皮部可以被分割成离散的单元，溶质被主动地重新加载到其中。这个问题的解决对于理解植物中碳水化合物运动背后的水力约束是至关重要的。鉴于韧皮部在连接光合作用和生长中的核心作用，对韧皮部运输的全面了解对于预测和潜在地修改植物如何应对改变的资源可用性和/或紧张的气候条件至关重要。该合作项目将支持一名研究生和一名博士后，并将为本科生提供研究机会。将积极征聘妇女和代表性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，每年接待超过25万名游客，其中包括许多学校团体。此外，作为“树木基础”系列丛书的一部分，植物园的网站上还将发布一个在线版本。第二次大画幅图像展览，伴随着教育材料，将在各种公共空间展出，从普尔曼开始，随后在整个州展出。

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.