Interactions between nanoparticles and plants: phytotoxicity and defense mechanisms

With the rapid development of nanotechnology, the potential releases of nanoparticles (NPs) have drawn considerable attention. Plants are essential fundamental components of all ecosystems, and the interaction between NPs and plants is an indispensable aspect of the risk assessment. Originally, this review focuses on NP phytotoxicity, which is an important precondition to promote the application of nanotechnology and to avoid the potential ecological risks. Both enhancive and inhibitive effects of various NPs on different plants’ growth have been documented. In this paper, the influence factors of nanotoxicity and the mechanisms of these toxic effects are also summarized. Subsequently, the defense mechanisms are presented as well. Eventually, this review puts forward the prospects of research direction of the environmental behavior and the biological toxicity of NPs, hoping to bring new ideas to the further research on NP phytotoxicity. Abbreviations: 1O2: singlet oxygen; AA: ascorbate; ABA: abscisic acid; APX: ascorbate peroxidase; B-Ag NPs: biosynthesized silver nanoparticles; Bt: Bacillus thuringiensis; CAT: catalase; CDs: carbon dots; Cu/Zn-SOD: copper/Zinc SOD; DHA: dehydroascorbate; DHAR: dehydroascorbate reductase; GA: gibberellic acid: GA-Ag NPs: coated silver nanoparticles; GPOX: guaiacol peroxidase; GPX: glutathione peroxidase; GR: glutathione reductase; GSH: glutathione; GSSG: oxidized glutathione; GST: glutathione S-transferases; •OH: hydroxyl radical; HA: high amylose; IAA: indole-3-acetic acid; LA: low amylose; MA: medium amylose; MDA: malondialdehyde; MDHAR: monodehydroascorbate reductase; NPs: nanoparticles; $\hbox{O}_ 2^{ \bullet - } $: superoxide radical; POD: promoting peroxidase; ROS: reactive oxygen species; SOD: superoxide dismutase; t-ZR: trans-zeatin-ribosid