| Manufactured nanomaterials have been widely applied in catalyst, biosensors, medical science and electronic industry fields due to their unique phychem ical properties. These nanomaterials would inevitably be exposed to the ecological environment in the processes of production, recycling and waste treatment, thus causing great adverse effects on animals and plants in the environment. More importantly, these pollutants may pose a potential threat to the whole ecosystem by entering the food chain through animals and plants in it. Although there have been several reports on phytotoxicity of nanoparticles, as well as their uptake and bio-accumulation in plants. However, it is necessary to supplement and complete the studies of negative effects and accumulation behaviors of some typical manufactured nanomaterials to the same plants species. Thus, in this work, the ffects of some common manufactured nanomaterials on growth indexes, oxidative stress, physiological function changes biosynthesis of rice seedling were inverstigated, as well as the uptake of nanomaterials in rice. Multi-wall carbon nanotubes(MWCNTs), zinc oxide nanoparticle(Zn ONPs), zinc sulfide nano particle(Zn SNPs) and copper oxide nanoparticles(Cu ONPs) were selected by hydroponic culturing with different concentrations(10, 50 and 100 mg/L). The results releaved phytotoxicity and uptake of nanomaterials in plants.After cultured in MWCNTs suspe nsions for 10 days, the results showed a significant loss(initial MWCNTs, 100 mg/L) in fresh weights of shoots and roots, which were decreased to be 87.6 ± 1.1 % and 69.2 ± 7.8 % of control respectively. The highest concentration(100 mg/L) of MWCNTs led to oxidative stress and cell membrane damage in root cells. When c ompared with the control sample, the catalase(CAT) activity was increased from 8.8 ± 1.6 to 16.3 ± 2.8 U/mg prot(protein). Simultaneously, the same increasing trend was found for malondial dehyde(MDA) content, which changed from 8.0 ± 0.3(the control) to 15.1 ± 1.4 μmol/g FW(fresh weight). Nevertheless, physiological enzymes activities decreased to a greater level even exposure to the lowest MWCNTs concentration(10 mg/L). For better anal ysis, transmission electron microscope(TEM) technology was adopted and the emergence of MWCNTs in TEM image further to verify the successful uptake of MWCNT in root cells.When dispersed in the culturing solutions, the characterizations of Zn ONPs, Zn SNPs and Cu ONPs on size distribution, Zeta potential and dissolved ions showed that Cu ONPs suspensions possessed higher dispersibility and stability than Zn ONPs and Zn SNPs. However, Zn ONPs dissolved much larger amount of metal ions than Cu ONPs and Zn SNPs. Thei r aggregated sizes all became smaller after 3 d ay’s culturing. It was appeared that Zn ONPs and Cu ONPs with higher concentrations(50 and 100 mg/L) could inhibit the growth indexes of rice seedlings both in roots and shoots, such as decrease the fresh/dry w eights and length of seedlings, increase ROS and MDA content and POD activity in root tissue, reduce root activity and chlorophyll content in leaves with different levels. For example, 50 and 100 mg/L of Zn ONPs decreased the fresh weight of roots to 47.3% and 44.3% of the control, respectively. 100 mg/L of Zn ONPs and Cu ONPs reduced the root vitality to 150.0 and 481.9 μg/g/h,for it was 710.4μg/g/h in control. Zn SNPs was found to promote the development and physiological function of rice seedlings in experim ental concentrations. 10 mg/L of Zn SNPs increased the fresh weight of shoots to 109.8% of control and 100 mg/L of which enhanced the root vitality to 2 times of control. In the same concentrations of Zn and Cu semiconductor nanoparticles treatments, rice seedlings could absorb more Zn and transfer it to shoots more easily than Cu. The study demonstrated that the phytotoxicity and bioaccumulation of mnufactured nanomaterials was related to physicochemical properties of nanoparticle suspensions and responses of plants to foreign toxics. |
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