title: Toxicogenomic Responses of the Model Legume Medicago truncatula to Aged Biosolids Containing a Mixture of Nanomaterials (TiO₂, Ag, and ZnO) from a Pilot Wastewater Treatment Plant.
abstract: Toxicogenomic responses in Medicago truncatula A17 were monitored following exposure to biosolids-amended soils. Treatments included biosolids produced using a pilot wastewater treatment plant with either no metal introduced into the influent (control); bulk/ionic TiO2, ZnO, and AgNO3 added to influent (bulk/dissolved treatment); or Ag, ZnO, and TiO2 engineered nanomaterials added to influent (ENM treatment) and then added to soil, which was aged in the field for 6 months. In our companion study, we found inhibition of nodulation in the ENM but not in the bulk/dissolved treatment. Gene expression profiling revealed highly distinct profiles with more than 10-fold down-regulation in 239 genes in M. truncatula roots from the ENM treatment, while gene expression patterns were similar between bulk/dissolved and control treatments. In response to ENM exposure, many of the identified biological pathways, gene ontologies, and individual genes are associated with nitrogen metabolism, nodulation, metal homeostasis, and stress responses. Expression levels of nine genes were independently confirmed with qRT-PCR. Exposure to ENMs induced unique shifts in expression profiles and biological pathways compared with bulk/dissolved treatment, despite the lack of difference in bioavailable metal fractions, metal oxidation state, and coordination environment between ENM and bulk/dissolved biosolids. As populations of Sinorhizobium meliloti Rm2011 were similar in bulk/dissolved and ENM treatments, our results suggest that inhibition of nodulation in the ENM treatment was primarily due to phytotoxicity, likely caused by enhanced bioavailability of Zn ions.
authors.affiliation: †Department of Plant and Soil Sciences, University of Kentucky, Lexington Kentucky 40546, United States.|‡Transatlantic Initiative for Nanotechnology and the Environment (TINE), University of Kentucky, Lexington, Kentucky 40546, Unites States.|§Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina 27708, United States.
authors.forename: Chun
authors.initials: C
authors.lastname: Chen
authors.affiliation: †Department of Plant and Soil Sciences, University of Kentucky, Lexington Kentucky 40546, United States.|‡Transatlantic Initiative for Nanotechnology and the Environment (TINE), University of Kentucky, Lexington, Kentucky 40546, Unites States.|§Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina 27708, United States.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Unrine
authors.affiliation: †Department of Plant and Soil Sciences, University of Kentucky, Lexington Kentucky 40546, United States.|‡Transatlantic Initiative for Nanotechnology and the Environment (TINE), University of Kentucky, Lexington, Kentucky 40546, Unites States.|§Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina 27708, United States.|∥CSIRO Land and Water, Waite Campus, Urrbrae, South Australia 5064, Australia.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Judy
authors.affiliation: †Department of Plant and Soil Sciences, University of Kentucky, Lexington Kentucky 40546, United States.|‡Transatlantic Initiative for Nanotechnology and the Environment (TINE), University of Kentucky, Lexington, Kentucky 40546, Unites States.
authors.forename: Ricky W
authors.initials: RW
authors.lastname: Lewis
authors.affiliation: ⊥Departments of Epidemiology and Biostatistics, University of Kentucky, Lexington Kentucky 40536, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Guo
authors.affiliation: †Department of Plant and Soil Sciences, University of Kentucky, Lexington Kentucky 40546, United States.|‡Transatlantic Initiative for Nanotechnology and the Environment (TINE), University of Kentucky, Lexington, Kentucky 40546, Unites States.
authors.forename: David H
authors.initials: DH
authors.lastname: McNear
authors.affiliation: †Department of Plant and Soil Sciences, University of Kentucky, Lexington Kentucky 40546, United States.|‡Transatlantic Initiative for Nanotechnology and the Environment (TINE), University of Kentucky, Lexington, Kentucky 40546, Unites States.|§Center for the Environmental Implications of Nanotechnology (CEINT), Duke University, Durham, North Carolina 27708, United States.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Tsyusko
mesh_terms: D015536:Down-Regulation / Q000187:drug effects; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D006706:Homeostasis / Q000187:drug effects / Q000235:genetics; D046913:Medicago truncatula / Q000187:drug effects* / Q000235:genetics; D049329:Nanostructures / Q000633:toxicity*; D009584:Nitrogen / Q000378:metabolism; D010865:Pilot Projects; D055170:Plant Root Nodulation / Q000187:drug effects / Q000235:genetics; D012722:Sewage / Q000737:chemistry*; D012834:Silver / Q000633:toxicity; D016962:Sinorhizobium meliloti; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D014025:Titanium / Q000633:toxicity; D043922:Toxicogenetics; D059467:Transcriptome / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification; D015034:Zinc Oxide / Q000633:toxicity
chemical_list: D009584:Nitrogen; D012722:Sewage; D012834:Silver; D014025:Titanium; D062065:Wastewater; D015034:Zinc Oxide; C009495:titanium dioxide