Study On The Combined Physiological Toxicity Of Nano-zinc Oxide And Multi-walled Carbon Nanotubes To Arabidopsis Thaliana

Nanomaterials will inevitably enter into the soil environment various ways during their production application in industry and agriculture.Nanomaterials may be potentially harmful to the plants growing in soil due to their unique physical and chemical properties,and through the biological chain transmission,bringing harm to the ecosystem and human health.Plants play a key role in the final fate and migration of nanoparticles in the environment,so it is important to understand the interaction between plants and nanomaterials.Firstly,the effects of nano-zinc oxide particles?nZnO?and multi-walled carbon nanotubes?MWCNTs?on Arabidopsis thaliana were studied.The results showed that the toxicity of nZnO to Arabidopsis thaliana was greater than that of MWCNTs.Next,the effects of nZnO and MWCNTs on Arabidopsis thaliana and its mechanism were studied.The results showed that the toxicity of binary nanocomposites to Arabidopsis thaliana was more significant,and two nanomaterials had synergistic effects.The growth of the main root and hypocotyls of Arabidopsis thaliana was inhibited and the chlorophyll content decreased.The contents of malondialdehyde?MDA?,hydrogen peroxide?H₂O₂?and activities of superoxide dismutase?SOD?and glutathione reductase?GR?were increased whereas glutathione?GSH?and catalase?CAT?were decreased significantly.The expression of SOD,CAT,GSH and GR related genes changed.Gene FSD1 and FSD2 were found to be significantly induced in shoots while,FSD2,CSD1 followed by MSD1 and FSD1 were found to be induced in roots,which indicated that differential gene regulation patterns underlined the increased SOD activities in different tissues;the decreased CAT activity was mainly due to the decreased expression level of CAT3,the up and down-regulation of GR1,GSH1 and GSH2 expression resulted in the increase and decrease activity of GR and GSH in Arabidopsis seedlings respectively.The results showed that single and binary pollution of nZnO and MWCNTs inhibited the growth and development of Arabidopsis thaliana,destroyed the antioxidant defense system in vivo,and showed differences in gene expression.Compared with single nano-material pollution,the combined toxicity of binary pollution to Arabidopsis thaliana was more significant.By studying the effects of single and binary pollution of nZnO and MWCNTs on Arabidopsis thaliana,The response of Arabidopsis thaliana to nZnO and MWCNTs combined pollution was analyzed at the genetic level,which provided theoretical guidance for the diagnosis,assessment and risk management of nanomaterials pollution,and supplemented and improved the basic data of ecotoxicology of nanomaterials pollutants.