Metal-Based Nanotoxicity and Detoxification Pathways in Higher Plants

Abstract

The potential risks from metal-based nanoparticles (NPs) in the environment have increased with the rapidly rising demand for and use of nanoenabled consumer products. Plant's central roles in ecosystem function and food chain integrity ensure intimate contact with water and soil systems, both of which are considered sinks for NPs accumulation. In this review, we document phytotoxicity caused by metal-based NPs exposure at physiological, biochemical, and molecular levels. Although the exact mechanisms of plant defense against nanotoxicity are unclear, several relevant studies have been recently published. Possible detoxification pathways that might enable plant resistance to oxidative stress and facilitate NPs detoxification are reviewed herein. Given the importance of understanding the effects and implications of metal-based NPs on plants, future research should focus on the following: (1) addressing key knowledge gaps in understanding molecular and biochemical responses of plants to NPs stress through global transcriptome, proteome, and metablome assays; (2) designing long-term experiments under field conditions at realistic exposure concentrations to investigate the impact of metal-based NPs on edible crops and the resulting implications to the food chain and to human health; and (3) establishing an impact assessment to evaluate the effects of metal-based NPs on plants with regard to ecosystem structure and function.

Uptake, translocation and physiological effects of magnetic iron oxide (γ-Fe2O3) nanoparticles in corn (Zea mays L.)

“…NPs could activate an antioxidant defense in corn root through inducing the oxidative stress, and plant, itself, could regulate SOD, CAT and POD activities to break down excess ROS. Furthermore, comparing with the previous studies, ROS generation and antioxidant enzyme activities may vary with exposure conditions, NPs type, and plant species (Ma et al, 2015b). For example, SOD activities in ryegrass (Lolium perenne L.) and pumpkin (Cucurbita mixta) exhibited different responses upon exposure to Fe 3 O 4 NPs .…”

“…2BeD shows the enzyme activity in corn roots and leaves treated with different concentrations of g-Fe 2 O 3 NPs. In plant cells, three types of SOD, containing Fe-SOD, Mn-SOD, and Cu-Zn-SOD, are able to rapidly convert O 2 À to H 2 O 2 (Ma et al, 2015b).…”

“…CAT is one of the common antioxidant enzymes that convert H 2 O 2 to H 2 O and O 2 (Ma et al, 2015b). As shown in Fig.…”

Effect of TiO2 Nanoparticles on Antioxidant Enzymes Activity and Biochemical Biomarkers in Pinto Bean (Phaseolus vulgaris L.)

“…Enzymes such as (superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), guaiacol peroxidase (GPX), malondialdehyde (MDA) content and 8-deoxy-2-hydroxyguanosine (8-OHDG) are generally altered as a response to the alternation in ROS concentration (Du et al, 2016). In this regard, it is reported that metal oxide nanoparticles exposure can induce the generation of ROS, consequently causing oxidative stress and activating plant responses for detoxification such as enzymatic activity (Ma et al, 2015). Similarly, Servin et al (2013), Hong et al (2005) and Song et al (2013) reported an increase in the activities of SOD, CAT, POD and decreased accumulation of ROS when plants were exposed to TiO 2 nanoparticle.…”

Parallel comparative studies on toxicity of quantum dots synthesized and surface engineered with different methods in vitro and in vivo

“…In this study, DNA-strand breaks in L02 liver cells were analyzed by comet assay. 32,41,42 The intensity of the comet tail relative to the head reflects the number of DNA breaks in a particular cell. Compared with the cells treated with QDs-1, longer comet tails extending toward the anode are observed in the cells exposed to QDs-2 and QDs-3, which is attributed to the DNA-strand breakage and loss of supercoiled structure ( Figure 2C).…”