A novel strategy for arsenic phytoremediation

砷植物修复的新策略

• 批准号: 10478512
• 负责人: Om Parkash Dhankher
• 金额: $ 4.93万
• 依托单位: UNIVERSITY OF MASSACHUSETTS AMHERST
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-09 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10478512
• 关键词: Aerobic; Arabidopsis; Arsenates; Arsenic; Arsenites; Binding; Biomass; C-terminal; Crambe abyssinica; Cysteine; Drug Metabolic Detoxication; Enzymes; Food; Genes; Genetic; Glutathione; Goals; Grain; Health; Human; Inorganic Phosphate Transporter; Knowledge; Mutation; Oryza sativa; Plant Roots; Plants; Play; RNA Interference; Rice; Role; Soil; Tissues; Transgenic Organisms; Translating; arsenate reductase; base; doctoral student; improved; knock-down; novel strategies; overexpression; phytochelatin; training project; uptake

Project Summary: The main objective of this supplemental project is to characterize arsenate reductase, ACR2, as a multifunctional enzyme for its role in arsenic tolerance, translocation, and limiting accumulation in food crops. Under aerobic conditions, plants absorb arsenate (AsV) from soil through phosphate transporters, and then AsV in roots is electrochemically reduced to arsenite (AsIII) by the activity of endogenous arsenate reductase, ACR2, or its homologs HAC1. AsIII is either extruded out of the roots or strongly binds to glutathione (GSH) and phytochelatins (PCs), which causes trapping most As belowground in the roots. Previously, to enhance the translocation of As to shoot tissues for phytoremediation purpose, we knocked down the AtACR2 expression using RNA interference (RNAi) in Arabidopsis. RNAi lines translocated 10- to 16-fold more As in shoots and retained less As in roots compared to wild-type plants. Therefore, arsenate reductases play a critical role in the translocation and accumulation of As in plants. Contrary to the results of RNAi knockdown of AtACR2, the overexpression of AtACR2 in Arabidopsis provided strong tolerance to AsV and caused a 50-75% reduction of As accumulation in aboveground shoot tissues. However, this multifunctional AtACR2 gene is not fully characterized and the mode of action in modulating the As tolerance/sensitivity and accumulation is not well understood. Arabidopsis AtACR2 contains a canonical arsenate reductase domain “HCX5R” and a highly cysteine- rich C-terminal domain. The canonical “HXC5R” and C-terminal Cys-rich domains are missing in the recently characterized alternate arsenate reductase HAC1. We speculate that “HCX5R” domain reduces AsV to AsIII, which binds to the Cys-rich C-terminal domain and hence provides AsIII tolerance. n the proposed supplemental training project, the PhD student trainee will characterize this AtACR2 gene to understand its role and mechanism of As tolerance and accumulation using a mutational approach by replacing the conserved Cys-residues in the C- terminus. Rice (Oryza sativa) is well known to accumulate high levels of As in edible grains. The ultimate goal of this supplemental project is to translate the knowledge into rice via overexpressing AtACR2 constitutively for increase tolerance and limiting As accumulation in the grains. The resulting transgenic rice lines overexpressing AtACR2 will be grown in As contaminated soils and will be analyzed for As tolerance and accumulation under greenhouse conditions. Therefore, the proposed project will lead to developing strategies for limiting As in rice to improve human health and thus will have a significant societal impact. This project is directly related, but not overlapped, to our R01 (Project ID: 1R01E032686-01) project “A novel strategy for arsenic phytoremediation”. The objective of the R01 project is to develop a genetics-based phytoremediation strategy for arsenic uptake, translocation, detoxification, and hyperaccumulation into the fast-growing, high biomass, non-food crop Crambe abyssinica.

项目概要： 该补充项目的主要目标是将砷酸还原酶 ACR2 作为一种多功能酶进行表征 因其在有氧条件下植物对砷的耐受性、易位和限制积累方面的作用。 通过磷酸转运蛋白从土壤中吸收砷酸盐（AsV），然后根部的AsV被电化学还原 通过内源性砷酸还原酶 ACR2 或其同源物 HAC1 的活性转化为亚砷酸盐 (AsIII)。 从根部挤出或与谷胱甘肽 (GSH) 和植物螯合素 (PC) 强烈结合，这会导致捕获大多数 以前在根部地下，以增强砷向芽组织的转运以进行植物修复。 为此，我们在拟南芥中使用 RNA 干扰 (RNAi) 敲低了 AtACR2 的表达。 与野生型植物相比，芽中的 As 转移量增加了 10 至 16 倍，而根部中的 As 保留量减少了。 砷酸还原酶在植物中砷的转运和积累中发挥着关键作用，这与研究结果相反。 AtACR2 的 RNAi 敲低、AtACR2 在拟南芥中的过表达提供了对 AsV 的强耐受性 然而，这种多功能的 AtACR2 导致地上芽组织中砷的积累减少了 50-75%。 基因尚未完全表征，并且调节 As 耐受性/敏感性和积累的作用模式尚不明确。 拟南芥 AtACR2 含有典型的砷酸还原酶结构域“HCX5R”和高度半胱氨酸。 典型的“HXC5R”和 C 端富含 Cys 的结构域在最近的研究中缺失。 我们推测“HCX5R”结构域将 AsV 还原为 AsIII。 与富含 Cys 的 C 末端结构域结合，因此在建议的补充训练中提供 AsIII 耐受性。 项目中，博士生学员将描述 AtACR2 基因的特征，以了解其作用和机制 通过替换 C- 中的保守 Cys 残基，使用突变方法来控制 As 耐受性和积累 众所周知，水稻 (Oryza sativa) 在食用谷物中积累了高含量的砷。 补充项目是通过组成型过度表达 AtACR2 将知识转化为水稻，以增加 过度表达 AtACR2 的转基因水稻品系将具有耐受性并限制砷在籽粒中的积累。 生长在砷污染的土壤中，将在温室下分析砷的耐受性和积累 因此，拟议的项目将导致制定限制水稻中砷的策略，以改善人类健康。 健康，因此将产生重大的社会影响 该项目与我们直接相关，但不重叠。 R01（项目 ID：1R01E032686-01）项目“砷植物修复的新策略”。 R01项目旨在开发一种基于遗传学的植物修复策略，用于砷的吸收、易位、解毒、 以及对快速生长、高生物量的非粮食作物海甘蓝的超积累。