es7b00422_si_004.mpg (4.94 MB)
Silver Nanoparticles and Wheat Roots: A Complex Interplay
media
posted on 2017-04-26, 00:00 authored by Ana E. Pradas del
Real, Vladimir Vidal, Marie Carrière, Hiram Castillo-Michel, Clément Levard, Perrine Chaurand, Géraldine SarretAgricultural
soils are major sinks of silver nanoparticles in the
environment, and crops are directly exposed to these emerging contaminants.
A clear picture of their chemical transformations, uptake and transport
mechanisms, and phytotoxic impacts is still lacking. In this work,
wheat plants were exposed to pristine metallic (Ag-NPs) and sulfidized
(Ag2S-NPs) silver nanoparticles and ionic Ag. Data on Ag
distribution and speciation, phytotoxicity markers, and gene expression
were studied. A multi-technique and multi-scale approach was applied,
combining innovating tools at both the laboratory and synchrotron.
Various chemical transformations were observed on the epidermis and
inside roots, even for Ag2S-NPs, leading to an exposure
to multiple Ag forms, which likely evolve over time. Genes involved
in various functions including oxidative stress, defense against pathogens,
and metal homeostasis were impacted in different ways depending upon
the Ag source. This study illustrates the complexity of the toxicity
pattern for plants exposed to Ag-NPs, the necessity of monitoring
several markers to accurately evaluate the toxicity, and the interest
of interpreting the toxicity pattern in light of the distribution
and speciation of Ag.