纳米TiO2在拟南芥中的富集、转运及对其生长和生理的影响

为了探讨纳米材料对植物的生理效应,以拟南芥(Arabidopsis thaliana)作为受试生物,研究了纳米TiO_2在拟南芥中的富集、转运及对其生长和生理的影响.本研究将拟南芥分别暴露于浓度为0、0.05、0.1、0.5、1.0、1.5 mg·L-1的纳米TiO_2中,通过ICP-MS测定纳米TiO_2在根和叶中的生物积累量,并采用TEM技术观察纳米TiO_2转运至叶片后对叶绿体结构的影响.在处理0、7和14 d后,测定拟南芥生物量、根系活力、叶片相对电导率和超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽(GSH)、活性氧自由基(ROS)等生长生理指标的变化.结果显示:拟南芥能吸收纳米TiO_2并向地上部转运,但转运系数较低;TEM切片观察到纳米TiO_2能进入拟南芥体内并造成叶绿体内囊体中质体小球数目增多、体积变大.与对照组相比,幼苗地上部生物量、叶片相对电导率、叶肉原生质体活力呈下降的趋势,地下部生物量及根系活力呈上升趋势;纳米TiO_2还可引起叶片及根部活性氧(ROS)含量的变化,进而导致MDA、SOD、GSH等抗氧化体系酶活性的应激变化,同时与根部相比,叶片引起的毒性效应更强.说明纳米TiO_2在拟南芥中富集并转运至地上部后,对拟南芥叶片的生长具有显著的抑制作用,诱导其产生氧化应激.同时,一定浓度的纳米TiO_2胁迫下,拟南芥根部与叶片对纳米TiO_2的响应不同,敏感度存在差异,叶生长受到抑制的同时却对根有促进作用.

Accumulation,transport of nano-TiO2 and their effects on growth and physiology in Arabidopsis thaliana

In order to investigate the impact of nano materials on plants, this investigation focused on the accumulation and transport of nano-TiO₂ in Arabidopsis thaliana and their effects on the growth and physiological responses. In this study, Arabidopsis thaliana was exposed to nano-TiO₂ of various concentrations (0, 0.05, 0.1, 0.5, 1.0, 1.5 mg·L^-1), the accumulation of nano-TiO₂ in roots and leaves were observed using ICP-MS, and the changes of chloroplast in leaves were observed using TEM. In the nano-TiO₂ treatment for 0, 7 and 14 d, we measured the changes of biomass, root activity, leaf relative conductivity and superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS) in treated Arabidopsis thaliana. The experimental group showed that Arabidopsis absorbs nano-TiO₂, which is then transported to the upper part; however, the transport coefficient was low. In addition, in the TEM slices, nano-TiO₂ was observed in the body of Arabidopsis, which exhibited a larger volume and a larger number of plastids. In contrast, the control group exhibited a decreasing pattern for the aboveground biomass, relative electrical conductivity of leaves, and the activity of mesophyll protoplasts. We also obersed that nano-TiO₂ leads to the change of reactive oxygen species (ROS) content in leaves, which further leads to the stress changes of MDA, SOD, GSH and other antioxidant enzymes. The results showed that the enrichment of nano-TiO₂ in Arabidopsis thaliana and the transport to the shoot had a significant inhibitory effect on the growth of Arabidopsis leaves and induced oxidative stress. At the same time with the stress of a certain concentration of nano-TiO₂, the response of root and leaf to nano-TiO₂ was different, also the sensitivity.