Foliar application of SiO2 and ZnO nanoparticles affected polycyclic aromatic hydrocarbons uptake of Amaranth (Amaranthus tricolor L.): A metabolomics and typical statistical analysis

Abstract

Nano-enabled foliar-application could be an ideal strategy for advancing agricultural productivity. However, it remains largely unknown whether they inhibit or promote the uptake of pollutants. Here, we systematically examined how foliar applying SiO2 nanoparticles (nSiO2) and ZnO nanoparticles (nZnO) (20 nm, 100 mg·L−1), influence polycyclic aromatic hydrocarbons (PAHs) uptake in 4-week-old amaranth (Amaranthus tricolor L.). Results showed that foliar application of nSiO2 or nZnO enhanced amaranth biomass by 20.2–26.4% but decreased PAHs bioaccumulation in leaves by 20.4–54.9% after 7-d incubation. Changes regarding amino acid-related pathways (alanine/aspartate/glutamate metabolism and arginine biosynthesis) and energy maintenance pathways (TCA cycle) were observed in amaranth leaves after foliar application of nSiO2 and nZnO. Specific PLS-DA analyses with total PAHs uptake as the biological endpoint showed that the contents of PAHs positively correlated with valine (R2 = 0.799) and tyrosine (R2 = 0.789), but negatively correlated with D-tagatose (R2 = 0.805) and L-gulonolactone (R2 = 0.877), indicating greater oxidant stress under higher PAHs level. We propose that mechanisms of declined uptake of PAHs involve the biomass-dependent dilute effect and activation of biological response against PAHs accumulation. These findings provide a prospective vision on how nano-enabled foliar-application alleviates PAH-enriched environmental burden while producing higher-yield agricultural products, especially for low toxic and biocompatible nSiO2.