Functional Analysis of Tocopherols in Plants and their Integration within the Plastid Antioxidant Network

植物中生育酚的功能分析及其在质体抗氧化网络中的整合

• 批准号: 0235929
• 负责人: Dean DellaPenna
• 金额: $ 58.5万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235929&HistoricalAwards=false
• 关键词: Functional; Analysis; Tocopherols; Plants; their

During its lifecycle, a plant is exposed to a wide range of abiotic and biotic stresses that can cause production of reactive oxygen species (ROS) in excess of that normally generated by metabolism and for signaling in the absence of stress. Although all subcellular compartments produce ROS, chloroplasts are the major ROS source in photosynthetic tissues. In order to avoid oxidative damage and death, plants have evolved an interconnected, complementary network of compounds (e.g., ascorbate, tocopherols, carotenoids, glutathione), enzymes (e.g., superoxide dismutases, peroxidases, catalases) and biochemical responses (e.g., non-photochemical quenching) that serve to minimize plastid ROS production under stressful conditions or rapidly detoxify excess ROS species or byproducts that are produced. Tocopherols, more commonly known as Vitamin E, are the major lipid soluble antioxidant in plastids and are proposed to be an essential component of the plastid antioxidant network. Studies in mammals and artificial membranes indicate tocopherols are important for membrane structure, quenching of singlet oxygen and other ROS, scavenging of chain-propagating lipid peroxy radicals and other "non-antioxidant" functions related to signaling and transcriptional regulation. In plants, tocopherols are assumed to function similarly though experimental evidence for this is lacking. During the past five years, the DellaPenna laboratory has cloned all enzymes of the tocopherol biosynthetic pathway in Arabidopsis and developed mutant/transgenic lines whose leaves are completely deficient in tocopherols or accumulate tocopherols at 4-5 times wild type levels. These tocopherol-modified lines will be used:1. To define the role(s) of tocopherols in scavenging specific ROS species and control of lipid peroxidation. 2. In genetic combinations with mutations that affect other components of the antioxidant network to assess functional compensation and redundancy of antioxidant network components.3. To study a novel germination phenotype in tocopherol deficient lines.4. In whole genome expression analysis to assess the response of individual antioxidant network genes and other cellular components to tocopherol modifications. Tocopherols, more commonly known as Vitamin E, are the major lipid soluble antioxidant in chloroplasts of all plants and are proposed to be an essential component of the plastid antioxidant network. The research being undertaken will provide a comprehensive understanding of tocopherol function(s) in photosynthetic tissues of Arabidopsis. This work will also define and characterize the integration and complementation of tocopherols with and by other components of the plastid antioxidant network (Vitamim C, carotenoids and enzymes that scavenge reactive oxygen). Because of the evolutionary conservation of the antioxidant network in chloroplasts, the data obtained will be of direct relevance to a wide range of plant species and crops.

在其生命周期中，植物暴露于广泛的非生物和生物胁迫下，这些胁迫会导致活性氧（ROS）的产生超过正常代谢产生的活性氧（ROS），并在没有胁迫的情况下发出信号。虽然所有亚细胞区室都产生活性氧，但叶绿体是光合组织中主要的活性氧来源。为了避免氧化损伤和死亡，植物已经进化出一个相互关联的互补网络，包括化合物（如抗坏血酸、生育酚、类胡萝卜素、谷胱甘肽）、酶（如超氧化物歧化酶、过氧化物酶、过氧化氢酶）和生化反应（如非光化学猝灭），以减少应激条件下质体ROS的产生，或迅速解毒产生的过量ROS物种或副产物。生育酚，通常被称为维生素E，是质体中主要的脂溶性抗氧化剂，被认为是质体抗氧化网络的重要组成部分。对哺乳动物和人工膜的研究表明，生育酚对膜结构、单线态氧和其他ROS的猝灭、清除链传播脂质过氧化自由基以及其他与信号和转录调节相关的“非抗氧化”功能都很重要。在植物中，虽然缺乏实验证据，但人们认为生育酚的功能与之相似。在过去的五年中，DellaPenna实验室克隆了拟南芥中生育酚生物合成途径的所有酶，并开发了叶片完全缺乏生育酚或生育酚积累水平为野生型4-5倍的突变/转基因品系。这些生育酚修饰系将用于：明确生育酚在清除特定活性氧和控制脂质过氧化中的作用。2. 2 .在影响抗氧化网络其他组成部分的突变基因组合中，评估抗氧化网络组成部分的功能补偿和冗余。研究一种新的生育酚缺乏品系的萌发表型。在全基因组表达分析中评估个体抗氧化网络基因和其他细胞成分对生育酚修饰的反应。生育酚，通常被称为维生素E，是所有植物叶绿体中主要的脂溶性抗氧化剂，被认为是质体抗氧化网络的重要组成部分。正在进行的研究将提供对拟南芥光合组织中生育酚功能的全面了解。这项工作还将定义和描述生育酚与质体抗氧化网络（维生素C、类胡萝卜素和清除活性氧的酶）的其他组成部分的整合和互补。由于叶绿体中抗氧化网络的进化保守性，所获得的数据将与广泛的植物物种和作物直接相关。