酸雨胁迫下镧在辣根累积及其对细胞结构的影响

Accumulation of Lanthanum in Horseradish Roots under Acid Rain Stress and Effect on Cellular Structure

稀土元素累积与酸雨同时出现在许多农业区,成为一个新的环境问题。然而,关于该同时胁迫的作用机制并不清楚。采用电感耦合等离子体质谱、扫描电镜-能谱仪及透射电镜调查La(Ⅲ)与酸雨(单一及同时)胁迫下辣根根系体内La含量,胞内La水平及细胞结构变化。实验结果显示,La(Ⅲ)与酸雨同时胁迫使辣根根系La含量和胞内La含量增加(20 mg·L^(-1)La(Ⅲ)和pH 4.5酸雨同时胁迫组除外),增幅随La(Ⅲ)浓度和酸雨强度增加而增大;低浓度(20 mg·L^(-1))La(Ⅲ)可缓解pH 4.5酸雨对根细胞结构的负作用,而高浓度La(Ⅲ)与酸雨同时胁迫对根细胞结构呈现协同效应。La(Ⅲ)在根系的累积对根细胞结构起到重要的调控作用,该作用与La(Ⅲ)浓度、酸雨强度和胁迫方式(单一或同时胁迫)密切相关。

It is a new environmental problem that the accumulation of rare earth elements（ REEs） and acid rain（ AR）simultaneously occur in many agricultural regions. However,the effect mechanism of the simultaneous stress is still unclear.Here,the single and simultaneous effects of La（ Ⅲ） and AR on the La content in root,intracellular La level and cellular structure of horseradish root were investigated by using inductively coupled plasma- mass spectrometry,scanning electron microscope- energy dispersive spectrometer and transmission electron microscopy. The results showed that the simultaneous stress of La（ Ⅲ） and AR increased the La content in root and intracellular La level（ except for the simultaneous treatment of 20 mg·L（-1）La（ Ⅲ） and p H 4. 5 AR）,the size of the increase got larger as the La（ Ⅲ） concentration and AR strength rose.A low concentration of La（ Ⅲ）（ 20 mg·L^（-1）） could alleviate the adverse effects of p H 4. 5 AR on the cellular structure of root,and the simultaneous stress at higher concentration of La（ Ⅲ） and AR had synergic effects on the cellular structure of root. In conclusion,the accumulation of La（ Ⅲ） in roots played an important role in the regulation of cellular structure of root. The role was closely related to La（ Ⅲ） dose,AR strength and treatment mode（ independent stress or simultaneous stress）.