A Comparative Study Of Toxicity Effect Of CuO Nanoparticles To Three Different Arabidopsis Thaliana

In recent years, due to their unique physical and chemical properties,Engineering Nanoparticles （ENPs） have been used more and more widely in industryand daily life, including paints, ceramics, textiles, pharmaceuticals, cosmetics,environmental remediation and other industries. However, with their wide application,more and more CuO ENPs will inevitably enter into aquatic and soil environment,which greatly increase the likelihood of human exposure to CuO ENPs. So thepotential hazards of CuO ENPs should not be ignored. Studies have shown that ENPshave toxic effects on microorganisms such as bacteria, algae, duckweed, mussels, fishand invertebrates. As the primary producers, plants play a very important role in thecycle of environmental and ecological systems. The researches on the environmentaleffects of exogenous pollutants often use plants as one of test organisms. Therefore, itis important to carry on the study of the chemical behavior of CuO ENPs in theenvironment and their toxic effects on plants，which have important scientificsignificance to the environmental risk assessment of CuO ENPs.Three different ecotypes of Arabidopsis thaliana were selected as test organisms.By means of hydroponic experiments, the toxic effects of ENPs were comparativelystudied to explore the effects of CuO ENPs on plant seedling growth in an aqueousenvironment. Finally one ecotype was chosen to be the most sensitive ecotype underENPs treatment. And bioaccumulation of ENPs in plant was studied using thatecotype. This study could provide the basic data for the follow-up work aboutmolecular toxic mechanism of CuO ENPs.Firstly, the effects of CuO ENPs on seed germination rate, germination energyand germination index during the seeds germination have been studied. The resultsindicate that the high concentration of CuO ENPs will slow down the germinationprocess of the Col-0ecotype, but there was no significant effect on seeds germinationof all ecotype. And then the effects of CuO ENPs on seedling growth in a hydroponics culture system were investigated. The researches showed that CuO ENPs can inhibitthe growth of the seedling and root elongation of Arabidopsis seedlings, leading to thedecline in seedling biomass and resulting in abnormal root morphology of seedlings.The root of seedlings exposed in CuO ENPs became shorter and thicker, root surfacearea and volume decreased, and root apical reduction in the number. During threeecotypes, Bay-0ecotype showed the greatest toxic effect on root morphology afterbeing exposed to CuO ENPs. Besides, CuO ENPs could inhibit the growth of seedlingleaves, and the leaf areas were reduced compared to the control. CuO ENPs have thesame effect on the leaf areas of Bay-0and Ws-2ecotype, while the effect on Col-0ecotype leaf area could be ignored.Through comprehensive analysis, Bay-0ecotype was determined to be the mostsensitive ecotype under CuO ENPs treatment. So bioaccumulation of ENPs in plantwas studied using Bay-0ecotype seedling. Finally, studies on the ability of CuO ENPsabsorbed by Arabidopsis seedlings have shown that the total copper content of shootsand roots of Arabidopsis seedling exposed to CuO ENPs was significantly increased.The roots copper content of seedling treated by50mg/L CuO ENPs was about22times than that in the control treatment. Besides, the copper content of the seedlingshoots was about20times than control and was1.5times than that under0.15mg/LCu²⁺treatment. These results indicated that CuO ENPs could enter into the plant bodyin some way. Furthermore, the translocation factor （TF） from root to shoot of copperwas0.028after Arabidopsis seedlings exposed to50mg/L CuO ENPs, indicating thatthe ability of CuO ENPs migrated from the roots to the aboveground by Arabidopsisis small, but CuO ENPs will also affect the growth of shoot.