Single-walled Carbon Nanotubes Phytotoxicity To Rice Seedling (Oryza Sativa L)

In recent years, with the rapid development of nanotechnology, carbon nanotubes(CNTs) are used in a wide range of industrial areas because of its large specific surface area and high surface energy as one new type of nanomaterials. However, CNTs will inevitably enter into the atmosphere, water and soil environment during the production, use and disposal process of CNTs, causing potentially adverse effects on the structure and function of ecosystems. Rice is a staple crop to the survival of mankind. CNTs will be released into environment and taken up by rice plants, and then eventually enter into human body through the food chains, thus constituting the potential risks to human health. Currently, relevant research mainly explored the toxic effects of CNTs on people, animals and microorganisms. However, the effect of CNTs on rice plants is not fully clear, and the toxic mechanism of CNTs to rice plants is still unknown. The purpose of this study isto investigate the effects of SWCNTs on seed germination rate, root length, fresh weight, dry weight, moisture content, chlorophyll, soluble protein contents, superoxide dismutase(SOD), catalase(CAT) and lipid peroxidation by means of hydroponic experiments, revealing the toxic impacts of SWCNTs on the growth of rice plants and trying to explore the phytotoxicity mechanism of SWCNTs. Simultaneously, we aim to study the accumulation of SWCNTs in rice seedlings and disclose the possible pathways of SWCNTs penetrating into rice seedlings and the distribution of SWCNTs in rice seedlings.Results showed that, in the germination period,compared with the control group, the germination rate did not change, seed germination process retarded. In the seedling growth period, roots length, fresh weight, dry weight, moisture content, chlorophyll and soluble protein of rice decreased with the increase of SWCNTs concentration. Further research also showed that SWCNTs could induce the increase of reactive oxygen species(ROS) in rice plants, excessive ROS inhibited the activities of SOD and CAT and caused lipid oxidation. Furthermore, SWCNTs were observed in the cell wall of rice roots epidermal cells by the method of TEM, suggesting that SWCNTs could be taken up by rice plants root.