羧基化多壁碳纳米管与镉复合干扰蚕豆幼苗生理特性的研究

Study on the Disturbation of Physiological Characteristics in Vicia faba L.Seedlings Exposed to Combination of Carboxylated Multi-Walled Carbon Nanotubes and Cadmium

为探究羧基化多壁碳纳米管(MWCNTs-COOH)复合镉(Cd)对蚕豆幼苗的毒性效应,利用水培实验研究了MWCNTs-COOH(0、1.5、3.0、6.0和12.0 mg·L^(-1))与Cd(10μmol·L^(-1))单一、复合胁迫下蚕豆幼苗生理的变化。结果表明,MWCNTs-COOH单一处理,随着其浓度的增加,根系活力呈下降趋势,当浓度达到12.0 mg·L^(-1)时,与对照相比下降35.7%;低浓度的MWCNTs-COOH促使叶绿素含量增加,且1.5 mg·L^(-1)MWCNTs-COOH显著诱导叶中过氧化物酶(POD)活性升高;6.0~12.0 mg·L^(-1)MWCNTs-COOH促进叶·O_(2)^(-)产生速率加快,超氧化物歧化酶(SOD)活性升高,叶中红褐色斑点增多;MWCNTs-COOH浓度为12.0 mg·L^(-1)时,根·O_(2)^(-)产生速率显著加快,SOD活性下降,根细胞染色加深,死亡加剧。MWCNTs-COOH与Cd复合后,当MWCNTs-COOH低于6.0 mg·L^(-1),与MWCNTs-COOH单一处理组比较,根系活力未见明显变化;增至6.0 mg·L^(-1)后,根系活力降低至10μmol·L^(-1)Cd单独处理组之下。所有复合处理组根和叶丙二醛(MDA)含量皆高于对应的MWCNTs-COOH单一处理,6.0 mg·L^(-1)MWCNTs-COOH复合Cd诱导根和叶POD活性增加,而12.0 mg·L^(-1)MWCNTs-COOH与Cd共同作用使叶中红褐色斑点加深且所占叶面积加大,达到64.02%,H_(2)O_(2)含量急剧增加,根尖细胞受损并部分脱落。因此,高浓度的MWCNTs-COOH能够加剧Cd对蚕豆幼苗的氧化胁迫。

In order to explore the joint toxic effects of carboxylated multi-walled carbon nanotubes(MWCNTs-COOH)and cadmium(Cd)on Vicia faba seedlings,the physiological changes of the seedlings hydroponically cultured in solution of MWCNTs-COOH(0,1.5,3.0,6.0,and 12.0 mg·L^(-1)),Cd(10μmol·L^(-1))alone or their combination were investigated in present experiments.The results showed that root activities tended to decrease with the increase of the single treatment concentration of MWCNTs-COOH.The root activity decreased by 35.7%at 12.0 mg·L^(-1)MWCNTs-COOH in comparison to that of the control.In addition,low concentrations of MWCNTs-COOH promoted the production of chlorophyll,and peroxidase(POD)activity was significantly elevated at 1.5 mg·L^(-1)MWCNTs-COOH compared with the control in the leaves.Moreover,·O_(2)^(-)production rates,superoxide dismutase(SOD)activities and reddish-brown spots were increased with the increase of MWCNTs-COOH concentration from 6.0 to 12.0 mg·L^(-1)in the leaves.In roots,at 12.0 mg·L^(-1)MWCNTs-COOH,the·O_(2)^(-)was significantly produced,and the SOD activity was obviously declined compared with the control.Additionally,the dead cells in stained roots increased under the treatment.Under the combination of MWCNTs-COOH and Cd,no obvious changes were observed in the root activities at the concentrations of MWCNTs-COOH lower than 6.0 mg·L^(-1),compared with the single MWCNTs treatments with the corresponding concentrations.When the MWCNTs-COOH increased up to 6.0 mg·L^(-1),the root activities decreased below that of 10μmol·L^(-1)Cd single treatment.Malondialdehyde(MDA)contents increased to be more than the corresponding treatment of MWCNTs-COOH in the roots or leaves under the combined treatments.POD activity was boosted in all the roots or leaves under the joint treatment by 6.0 mg·L^(-1)MWCNTs-COOH and 10μmol·L^(-1)Cd.Particularly,the reddish-brown spots were expanded to 64.02%,and hydrogen peroxide production was markedly accumulated in the leaves,while the root tip cells were damaged and partially fell off the roots under the combination of 12.0 mg·L^(-1)MWCNTs-COOH and 10μmol·L^(-1)Cd.Thus,it can be concluded that higher concentrations of MWCNTs-COOH(no less than 6.0 mg·L^(-1))may exacerbate the oxidative stress in V.faba seedlings exposed to Cd in culture solution.