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MUCILAGE: the hydraulic bridge between roots and soil

粘液：根部和土壤之间的水力桥梁

基本信息

批准号：
252464214
负责人：
Professor Dr. Andrea Carminati
金额：
--
依托单位：
Universitätsleitung - Präsidium
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/252464214?language=en
关键词：
MUCILAGE hydraulic bridge between roots

项目摘要

Water is the source for plant growth. In times of climate change, water scarcity will endanger food production worldwide. One mitigation strategy for sustaining food production is to improve the capability of crops to capture water from soils. The central hypothesis of our project is that mucilage exuded by roots favors the water flow into roots and it increases plant drought tolerance. We hypothesize that mucilage alters the physicochemical properties of the rhizosphere, in particular its water holding capacity and hydraulic conductivity, and that these alterations affect the water flow across the rhizosphere. Thanks to its high water holding capacity, mucilage maintains the rhizosphere wet and helps roots to stay in hydraulic contact with soil during drought, improving the hydraulic conductivity of the root-soil interface. However, as mucilage dries, it becomes hydrophobic and it may reduce the local root uptake. It is not clear whether such temporary hydrophobicity is a problem for the acquisition of water or, on the contrary, it is a strategy of plants to not lose water when the soil becomes too dry. Furthermore, it is not known how such characteristics depend on plant species and soil types. Objective of our project is to understand the mechanistic role of mucilage for the regulation of water supply to plants. We structured the project in three sub-projects with the following tasks: 1) to measure the physiochemical properties of mucilage, and in particular the binding characteristics and mobility of water in mucilage; to this end we will employ1H-NMR-relaxometry, diffusometry and differential scanning calorimetry. 2) To measure the water retention curve and the hydraulic conductivity of soil-gel mixtures; to this end we will mix PGA-Ca (model for mucilage) and real mucilage (collected from different Fabaceae and Poaceae) with soils of different particle size distribution. In a first step, the gel will be homogeneously mixed with sand; then it will be added around artificial roots (suction cups) to mimic mucilage distribution in the rhizosphere. 3) To measure the effects of mucilage and rhizosphere on root water uptake. To this end a root pressure probe will be applied to single roots grown in soils. The measurements will be coupled with neutron radiography of water distribution in the rhizosphere. The experiments will be simulated with a numerical model of water flow into a single root including mucilage-rhizosphere dynamics. The three sub-projects are planned to stepwise link the processes at the supramolecular scale with the macroscopic soil hydraulic properties and root water uptake. The expected outcome of the project is the understanding of the role of mucilage on soil-plant water relations and its importance for improving plant drought tolerance.

水是植物生长的源泉。在气候变化时期，水资源短缺将危及全球粮食生产。维持粮食生产的一项缓解战略是提高作物从土壤中获取水分的能力。我们的项目的中心假设是，根系分泌的粘液有利于水分流入根系，它增加了植物的耐旱性。我们假设，粘液改变根际的物理化学性质，特别是它的持水能力和水力传导性，这些改变会影响整个根际的水流。由于其高持水能力，粘液保持根际湿润，并帮助根系在干旱期间保持与土壤的水力接触，提高根-土界面的水力传导性。然而，随着粘液干燥，它变得疏水，它可能会减少局部根吸收。目前尚不清楚这种暂时的疏水性是否是获取水分的问题，或者相反，这是植物在土壤变得过于干燥时不失去水分的策略。此外，尚不清楚这些特征如何取决于植物种类和土壤类型。我们的项目的目的是了解机械作用的粘液调节供水植物。我们将该项目分为三个子项目，任务如下：1）测量粘液的理化性质，特别是粘液中水的结合特性和流动性;为此，我们将采用1H-NMR-弛豫法，扩散法和差示扫描量热法。2)为了测量土壤-凝胶混合物的水分保持曲线和水力传导率;为此，我们将PGA-Ca（粘液模型）和真实的粘液（从不同的豆科和禾本科植物中收集）与不同粒度分布的土壤混合。在第一步中，将凝胶与沙子均匀混合;然后将其添加到人工根（吸盘）周围，以模拟根际中的粘液分布。3)研究根际土壤和土壤粘液对根系吸水的影响。为此，将对土壤中生长的单根应用根压探针。这些测量将与根际水分分布的中子射线照相术相结合。实验将模拟水流进入一个单一的根，包括粘液根际动力学的数值模型。这三个子项目计划逐步将超分子尺度的过程与宏观土壤水力特性和根系吸水联系起来。该项目的预期成果是了解粘液对土壤-植物水分关系的作用及其对提高植物耐旱性的重要性。