title: Evidence of translocation and physiological impacts of foliar applied CeO2 nanoparticles on cucumber (Cucumis sativus) plants.
abstract: Currently, most of the nanotoxicity studies in plants involve exposure to the nanoparticles (NPs) through the roots. However, plants interact with atmospheric NPs through the leaves, and our knowledge on their response to this contact is limited. In this study, hydroponically grown cucumber (Cucumis sativus) plants were aerially treated either with nano ceria powder (nCeO2) at 0.98 and 2.94 g/m(3) or suspensions at 20, 40, 80, 160, and 320 mg/L. Fifteen days after treatment, plants were analyzed for Ce uptake by using ICP-OES and TEM. In addition, the activity of three stress enzymes was measured. The ICP-OES results showed Ce in all tissues of the CeO2 NP treated plants, suggesting uptake through the leaves and translocation to the other plant parts. The TEM results showed the presence of Ce in roots, which corroborates the ICP-OES results. The biochemical assays showed that catalase activity increased in roots and ascorbate peroxidase activity decreased in leaves. Our findings show that atmospheric NPs can be taken up and distributed within plant tissues, which could represent a threat for environmental and human health.
authors.affiliation: Environmental Science and Engineering PhD Program, The University of Texas at El Paso , 500 West University Avenue, El Paso, Texas 79968, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Hong
authors.forename: Jose R
authors.initials: JR
authors.lastname: Peralta-Videa
authors.forename: Cyren
authors.initials: C
authors.lastname: Rico
authors.forename: Shivendra
authors.initials: S
authors.lastname: Sahi
authors.forename: Marian N
authors.initials: MN
authors.lastname: Viveros
authors.forename: Jane
authors.initials: J
authors.lastname: Bartonjo
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhao
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Gardea-Torresdey
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001692:Biological Transport; D002563:Cerium / Q000378:metabolism*; D018553:Cucumis sativus / Q000201:enzymology / Q000648:ultrastructure; D057075:Enzyme Assays; D018527:Hydroponics; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D018515:Plant Leaves / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure; D011208:Powders; D013997:Time Factors
chemical_list: D000975:Antioxidants; D011208:Powders; D002563:Cerium; C030583:ceric oxide