Collaborative Research: Physiology of Long Distance Assimilate Transport

地球上生命的基础是通过植物中发生的光合作用将太阳能转化为化学能。光合作用的高能量最终产物是糖，糖必须通过称为韧皮部的组织从产生部位（在大多数情况下是叶子）转移到消耗和储存部位（茎，根，果实）。人类要么直接以沙拉、谷物、蔬菜等形式消耗富含能量的植物组织，或者间接地通过食用肉类，肉类是由动物食用植物产生的。糖在韧皮部内的转运是生产高质量、高产量和健康食品的关键机制。例如，如果通过韧皮部的糖输出不足，则植物的光合作用主动减少。蚜虫等害虫攻击韧皮部，将它们的口器插入组织中并以富含糖的溶液为食，这导致产量损失。植物病毒通过韧皮部传播并对植物造成严重损害。尽管韧皮部在植物生长和粮食生产中起着重要作用，但人们对韧皮部装载和运输的基本过程知之甚少。该项目将研究糖通过叶子的流动路径，糖进入或“装载”到韧皮部以及糖在植物中的分布。加强对韧皮部装载和运输的理解可能会导致新的策略，以保护植物免受害虫，提高作物产量，并通过减少或消除农药的应用，生产更健康的食品。该奖项的目标是调查韧皮部装载的生理参数和运输的物理长韧皮部网络的植物（葡萄树和树木）。在以前的奖项开发的方法将被用来生成细胞和组织类型的叶概述膨压和韧皮部流动模式在不同的静脉顺序的地图。此外，细胞和组织之间的胞间连丝的分布，以及从源细胞到筛管的细胞间传导性也将被绘制出来。测量筛管膨压和流速的新系统，以及简单的基于SEM的方法将用于收集关于胞间连丝频率和筛板结构的数据。植物大小和源膨压和韧皮部结构之间的关系，在树木和葡萄树与不同的负载类型也将进行调查。这将使目前的模型韧皮部运输重新参数化，以更好地反映通过植物的光合同化物运输的途径的水力结构。该奖项还将汇集专门从事植物细胞生物学和血管运输的研究人员，并支持博士后研究人员和研究生的教育和培训，以及让本科生参与研究，并为高中学生和教师提供学习植物中光合同化物运输的机会。

The basis for life on earth is the conversion of solar energy into chemical energy by a process called photosynthesis that takes place in plants. The high energy containing end product of photosynthesis is sugar that has to be translocated, via a tissue called phloem, from the site of generation (in most cases leaves) to the sites of consumption and storage (stems, roots, fruits). Humans either consume energy rich plant tissues directly in the form of salads, cereals, vegetables etc., or indirectly via the consumption of meat, which was produced by animals consuming plants. The translocation of sugars within the phloem is a key mechanism in the production of high quality, high yield, and healthy food. For example, photosynthesis is actively reduced by the plant if export of sugars through the phloem is insufficient. Pests like aphids attack the phloem, insert their mouthparts into the tissue and feed on the sugar rich solution, which results in loss of production. Plant viruses travel through the phloem and cause severe damage to the plant. Despite the central role the phloem plays in plant performance and food production, the knowledge of the underlying processes of phloem loading and transport are poorly understood. This project will investigate the flow path of sugars through leaves, the entry or "loading" of sugars into the phloem and the distribution of sugars within the plant. Enhanced understanding of phloem loading and transport could lead to new strategies to protect plants from pests, to increase crop yield and to produce healthier food by reducing or eliminating the necessity for application of pesticides.The goal of this award is to investigate physiological parameters of phloem loading and the physics of transport in plants with long phloem networks (vines and trees). Methods developed during previous awards will be used to generate cell and tissue-type based maps of leaves outlining turgor pressure and phloem flow patterns in different vein orders. In addition, the distribution of plasmodesmata between cells and tissues, and cell-to-cell conductivity from source cells to sieve tubes will be mapped. New systems to measure sieve tube turgor and flow velocity, as well as straightforward SEM based methods will be used to gather data on plasmodesmal frequencies and sieve plate structure. The relationship between plant size and source turgor pressure and phloem architecture in trees and vines with different loading types will also be investigated. This will allow current models of phloem transport to be re-parameterized so as to reflect better the hydraulic architecture of the pathway for photoassimilate transport through the plant. This award will also bring together researchers specializing in plant cell biology and vascular transport, and support education and training for a postdoctoral researcher and graduate students, as well as engage undergraduates in research and provide opportunities for high-school students and teachers to learn about the transport of photoassimilates in plants.