title: Exposure of cerium oxide nanoparticles to kidney bean shows disturbance in the plant defense mechanisms.
abstract: Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO2) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of ∼ 8 ± 1 nm nCeO2 (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO2 exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron μ-XRF mapping, and the chemical forms were identified using μ-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO2, although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO2/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO2 exposure in order to maintain cellular homeostasis.
authors: Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; University of California Center for Environmental Implications of Nanotechnology (UC CEIN), USA.
authors: Sanghamitra
authors: S
authors: Majumdar
authors: Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; University of California Center for Environmental Implications of Nanotechnology (UC CEIN), USA.
authors: Jose R
authors: JR
authors: Peralta-Videa
authors: Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; University of California Center for Environmental Implications of Nanotechnology (UC CEIN), USA.
authors: Susmita
authors: S
authors: Bandyopadhyay
authors: European Synchrotron Radiation Facility, B.P. 220-38043 Grenoble, Cedex, France.
authors: Hiram
authors: H
authors: Castillo-Michel
authors: Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; University of California Center for Environmental Implications of Nanotechnology (UC CEIN), USA.
authors: Jose-Angel
authors: JA
authors: Hernandez-Viezcas
authors: Department of Biology, Western Kentucky University, Bowling Green, KY 42101, USA.
authors: Shivendra
authors: S
authors: Sahi
authors: Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 USA; University of California Center for Environmental Implications of Nanotechnology (UC CEIN), USA. Electronic address: jgardea@utep.edu.
authors: Jorge L
authors: JL
authors: Gardea-Torresdey
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002563:Cerium / Q000494:pharmacology / Q000633:toxicity*; D053768:Metal Nanoparticles / Q000633:toxicity*; D009195:Peroxidase / Q000378:metabolism; D027805:Phaseolus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D035261:Plant Components, Aerial / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D002563:Cerium; C030583:ceric oxide; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase
keywords: Antioxidant enzymes; Cerium oxide nanoparticles; Phaseolus vulgaris; Synchrotron micro-x-ray absorption spectroscopy; Translocation