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Studies on phytotoxicities of carbon nanomaterials in seedling stage
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| Title: | Studies on phytotoxicities of carbon nanomaterials in seedling stage |
| Other Titles: | 植物の実生段階における炭素ナノ材料の毒性評価に関する研究 |
| Authors: | Ikhtiari, Refi Browse this author |
| Issue Date: | 25-Mar-2014 |
| Publisher: | Hokkaido University |
| Abstract: | Carbon nanomaterials(CNMs) which represented by graphene oxide(GO) and carbon nanotubes(CNTs) have been widely applied in nano science and nano industry. The use of CNMs was supposed contribute to negative consequences related to their environmental exposure to human, animal and plant. Therefore the biological effect of CNMs has been evaluated intensively and urgently suggested that the studies of their environmental fate would be very important in the field of nano-toxicology. The effects of graphene oxide(GO) on root and shoot growth, biomass, shape, cell death, and reactive oxygen species(ROS) of cabbage, tomato, red spinach, and lettuce, were investigated using a concentration range from 500 to 2000 mg/L. The results of the combined morphological and physiological analysis indicate that after 20 days of exposure under our experimental conditions, GO significantly inhibited plant growth and biomass compared to a control. The number and size of leaves of the GO - treated plants were reduced in a dose-dependent manner. Significant effects also were detected showing a concentration dependent increase in ROS and cell death as well as visible symptoms of necrotic lesions, indicating GO -induced adverse effects on cabbage, tomato, and red spinach mediated by oxidative stress necrosis. Little or no significant toxic effect was observed with lettuce seedlings under the same conditions. The potential effect of GO largely depends on dose, exposure time, and plant. Abundant experimental data have shown that multiwall carbon nanotubes(MWNTs) are toxic to plants, but the potential impacts of exposure remain unclear. The objective of the present study was to evaluate possible phytotoxicity of MWNTs at 0, 20, 200, 1000, and 2000 mg/L with red spinach, lettuce, rice, cucumber, chili, lady's finger, and soybean based on root and shoot growth, cell death, and electrolyte leakage at the seedling stage. After 15 days of hydroponic culture, the root and shoot lengths of red spinach, lettuce, and cucumber were significantly reduced following exposure to 1000 mg/L and 2000 mg/L MWNTs. Similar toxic effects occurred regarding cell death and electrolyte leakage. Red spinach and lettuce were most sensitive to MWNTs, followed by rice and cucumber. Very little or no toxic effects were observed for chili, lady's finger, and soybean. Further, we investigated the phytotoxicity of MWNTs on lettuce regarding inhibition effect on plant growth development as well as cell damage on root and leaves. We have cultured the plant seeding of lettuce using Hoagland's Media treated with MWNTs hydroponically. After two weeks, we observed the toxic symptoms in the presence of MWNTs in a dose-dependent manner as compared to carbon black(CB). Statistically, MWNTs could inhibit the seed germination, plant growth and plant biomass. Microscopic analysis showed the attachment of MWNTs on the root surface area, deterioration of root tip and an image of penetration of MWNTs into plant cell wall. We also showed that MWNTs caused cell death on root and leaves. In situ detection of hydrogen peroxide has proposed the Reactive oxygen species(ROS) for mechanism of toxic effect of MWNTs. In general conclusion, CNMs may not negatively affect all crop species at low concentration; however in some cases apoptosis were found. But at high concentration, CNMs could induce the overproduction of ROS through oxidative stress mechanism which visibly detected as necrotic lesions. |
| Conffering University: | 北海道大学 |
| Degree Report Number: | 甲第11339号 |
| Degree Level: | 博士 |
| Degree Discipline: | 環境科学 |
| Examination Committee Members: | (主査) 教授 古月 文志, 教授 田中 俊逸, 特任教授 荒井 眞一, 助教 藏崎 正明, 准教授 赤坂 司 （大学院歯学研究科） |
| Degree Affiliation: | 環境科学院（環境起学専攻） |
| Type: | theses (doctoral) |
| URI: | http://hdl.handle.net/2115/55382 |
| Appears in Collections: | 学位論文 (Theses) > 博士 （環境科学）
課程博士 (Doctorate by way of Advanced Course) > 環境科学院(Graduate School of Environmental Science)
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