TY - JOUR
T1 - Comparative phytotoxicity of ZnO NPs, bulk ZnO, and ionic zinc onto the alfalfa plants symbiotically associated with Sinorhizobium meliloti in soil
AU - Bandyopadhyay, Susmita
AU - Plascencia-Villa, Germán
AU - Mukherjee, Arnab
AU - Rico, Cyren M.
AU - José-Yacamán, Miguel
AU - Peralta-Videa, Jose R.
AU - Gardea-Torresdey, Jorge L.
N1 - Funding Information:
This material is based upon work supported by the National Science Foundation and the Environmental Protection Agency under Cooperative Agreement Number DBI-0830117 . Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Environmental Protection Agency. This work has not been subjected to EPA review and no official endorsement should be inferred. This work was supported by Grant 2G12MD007592 from the National Institutes on Minority Health and Health Disparities (NIMHD) , a component of the National Institutes of Health (NIH). The authors also acknowledge USDA grant number 2011-38422-30835 , and NSF Grant # CHE-0840525 . J. L. Gardea-Torresdey acknowledges the Dudley family for the Endowed Research Professorship in Chemistry. The authors acknowledge Chuan Xiao, for using his spectroscopy facility. We also acknowledge the Facilities of Kleberg Advanced Microscopy Center (KAMiC) and NIH RCMI Nanotechnology and Human Health Core NIH RCMI Biophotonics Core (Grant 5G12RR013646-12 and Grant G12MD007591) at The University of Texas at San Antonio (UTSA).
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/5/5
Y1 - 2015/5/5
N2 - ZnO nanoparticles (NPs) are reported as potentially phytotoxic in hydroponic and soil media. However, studies on ZnO NPs toxicity in a plant inoculated with bacterium in soil are limited. In this study, ZnO NPs, bulk ZnO, and ZnCl2 were exposed to the symbiotic alfalfa (Medicago sativa L.)-Sinorhizobium meliloti association at concentrations ranging from 0 to 750mg/kg soil. Plant growth, Zn bioaccumulation, dry biomass, leaf area, total protein, and catalase (CAT) activity were measured in 30day-old plants. Results showed 50% germination reduction by bulk ZnO at 500 and 750mg/kg and all ZnCl2 concentrations. ZnO NPs and ionic Zn reduced root and shoot biomass by 80% and 25%, respectively. Conversely, bulk ZnO at 750mg/kg increased shoot and root biomass by 225% and 10%, respectively, compared to control. At 500 and 750mg/kg, ZnCl2 reduced CAT activity in stems and leaves. Total leaf protein significantly decreased as external ZnCl2 concentration increased. STEM-EDX imaging revealed the presence of ZnO particles in the root, stem, leaf, and nodule tissues. ZnO NPs showed less toxicity compared to ZnCl2 and bulk ZnO found to be growth enhancing on measured traits. These findings are significant to reveal the toxicity effects of different Zn species (NPs, bulk, and ionic Zn) into environmentally important plant-bacterial system in soil.
AB - ZnO nanoparticles (NPs) are reported as potentially phytotoxic in hydroponic and soil media. However, studies on ZnO NPs toxicity in a plant inoculated with bacterium in soil are limited. In this study, ZnO NPs, bulk ZnO, and ZnCl2 were exposed to the symbiotic alfalfa (Medicago sativa L.)-Sinorhizobium meliloti association at concentrations ranging from 0 to 750mg/kg soil. Plant growth, Zn bioaccumulation, dry biomass, leaf area, total protein, and catalase (CAT) activity were measured in 30day-old plants. Results showed 50% germination reduction by bulk ZnO at 500 and 750mg/kg and all ZnCl2 concentrations. ZnO NPs and ionic Zn reduced root and shoot biomass by 80% and 25%, respectively. Conversely, bulk ZnO at 750mg/kg increased shoot and root biomass by 225% and 10%, respectively, compared to control. At 500 and 750mg/kg, ZnCl2 reduced CAT activity in stems and leaves. Total leaf protein significantly decreased as external ZnCl2 concentration increased. STEM-EDX imaging revealed the presence of ZnO particles in the root, stem, leaf, and nodule tissues. ZnO NPs showed less toxicity compared to ZnCl2 and bulk ZnO found to be growth enhancing on measured traits. These findings are significant to reveal the toxicity effects of different Zn species (NPs, bulk, and ionic Zn) into environmentally important plant-bacterial system in soil.
KW - Bulk ZnO
KW - General plant behavior
KW - Ionic Zn
KW - Toxicity
KW - Zn uptake
KW - ZnO nanoparticles
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U2 - 10.1016/j.scitotenv.2015.02.014
DO - 10.1016/j.scitotenv.2015.02.014
M3 - Article
C2 - 25698520
AN - SCOPUS:84923037440
SN - 0048-9697
VL - 515-516
SP - 60
EP - 69
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -