Flavonoid Regulation of Root Architecture and Reactive Oxygen Species Signaling

植物必须有高度分枝的根系，才能有效地获得水分和养分。由于全球气候变化，干旱正在世界范围内变得更加普遍，这促使人们需要深入了解根系结构，以最大限度地吸收水分，从而可能导致发展耐旱作物。这个项目探索了类黄酮是如何控制根部结构的，类黄酮是一种由植物制造的化学物质，具有抗氧化剂的功能。类黄酮类抗氧化剂降低了活性氧物种(ROS)的水平，ROS是帮助植物适应紧张生长条件的信号分子，但在高水平时会变得有毒。ROS信号在植物对光、温度和干旱的反应中起着重要作用。这个项目研究了依赖ROS的信号通路是如何被诱导的，以及类黄酮是如何限制这些信号以防止氧化损伤的。计划中的实验将使用具有改变类黄酮合成的突变的植物来展示类黄酮何时何地改变根中的ROS水平，以及类黄酮的积累如何改变根构型。该项目还将探索ROS调节蛋白质活性和基因表达的机制。该项目还将支持制定一项针对高中生的案例研究练习，教授植物遗传学、植物如何应对干旱以及植物常规育种和基因工程培育耐旱作物品种的潜力。该团队将把大学生带到高中课堂，带领学生完成这门课程，更好地理解这些概念以及它们如何应用于农业。本项目将研究活性氧(ROS)作为信号分子控制根发育的作用，并研究类黄酮类化合物如何清除ROS来调节发育。本项目应用遗传学、分子生物学和生物化学的方法来检测和操纵模式植物拟南芥的类黄酮生物合成途径，以探讨类黄酮对根构型的影响是否是其抗氧化作用的结果。我们手中的突变体在类黄酮生物合成的大多数步骤中都存在缺陷，我们将利用这些突变体来确定哪些类黄酮控制根构型。我们将使用共聚焦显微镜和检测特定活性氧物种的探针来定位和定量ROS，以确定ROS的积累和分布是否受这些突变体中发现的不同黄酮类积累谱的调节。我们将使用遗传和化学方法来操纵ROS和ROS清道夫的水平，以证明类黄酮/ROS的相互作用与根的发育直接相关。最后，我们将通过探索转录网络的变化和使用无偏见的蛋白质组学方法来识别在黄酮醇依赖的机制中被ROS可逆修饰的蛋白质，从而确定类黄酮调节的ROS控制根发育的机制。然后，将使用突变方法测试受ROS调控的基因产物或ROS氧化蛋白的功能。

Plants must have a highly branched root system for efficient moisture and nutrient acquisition. As a result of global climate change, drought is becoming more prevalent world-wide, driving the need for insight into root architecture that maximizes water uptake that may lead to development of drought tolerant crops. This project explores how root architecture is controlled by flavonoids, which are chemicals made by plants that function as antioxidants. Flavonoid antioxidants reduce the levels of reactive oxygen species (ROS), which act as signaling molecules to help plants adapt to stressful growth conditions, but can become toxic at high levels. ROS signals play important roles in the response of plants to changes in light, temperature, and drought. This project examines how ROS-dependent signaling pathways are induced and how flavonoids limit these signals to prevent oxidative damage. The planned experiments will use plants with mutations that alter flavonoid synthesis to demonstrate when and where flavonoids alter ROS levels in roots and how the accumulation of flavonoids alters root architecture. This project will also explore the mechanisms by which ROS modulates activity of proteins and expression of genes. This project will also support the development of a case study exercise targeted to high school students, which teaches plant genetics and how plants respond to drought and the potential of conventional breeding and genetic engineering of plants to lead to drought tolerant crop varieties. The team will bring college students to high school classrooms to lead students through this curriculum to better understand these concepts and how they apply to agriculture. This project will examine the role of reactive oxygen species (ROS) as signaling molecules that control root development and examine how flavonoids scavenge ROS to modulate development. This project applies genetic, molecular biological, and biochemical approaches to examine and manipulate the flavonoid biosynthetic pathway in the model plant species of Arabidopsis thaliana to ask whether flavonoid effects on root architecture are the result of their antioxidant action. We have in hand mutants with defects at most steps in flavonoid biosynthesis, which we will use to determine which flavonoids control root architecture. We will localize and quantify ROS using confocal microscopy with a probes that detect specific reactive oxygen species to determine whether ROS accumulation and distribution are modulated by the different flavonoid accumulation profiles found in these mutants. We will use genetic and chemical approaches to manipulate the levels of ROS and ROS scavengers to demonstrate that flavonoid/ROS interplay is directly linked to root development. Finally, we will identify the mechanisms by which flavonoid-modulated ROS controls root development by exploring changes in transcriptional networks and using an unbiased proteomic approach to identify proteins that are reversibly modified by ROS in a flavonol-dependent mechanism. The function of ROS regulated gene products or ROS oxidized proteins will then be tested using a mutant approach.