纳米氧化铜(CuO NPs)对紫花苜蓿幼苗根系活性氧(ROS)、抗氧化酶活性和根系活力的影响

根系通常是植物直接受到外界环境物质(如重金属离子和纳米金属氧化物)毒害的主要器官。本研究以紫花苜蓿的幼苗为实验材料,探讨了CuO NPs胁迫对紫花苜蓿幼苗根系的活性氧(ROS)积累、抗氧化酶活性和根系活力的影响。研究结果表明:(1)不同浓度的CuO NPs对紫花苜蓿幼苗根系H_2O_2和O-2·含量具有显著影响。随CuO NPs浓度增大,紫花苜蓿幼苗根系中H_2O_2和O-2·整体上呈现先增大后减少的趋势,除了0.00125 mol·L~(-1)CuO NPs浓度下紫花苜蓿幼苗根系中H_2O_2含量比对照减少外,其他浓度下的H_2O_2和O-2·的含量都比对照有所增加,并且H_2O_2和O-2·的含量都是在0.0125 mol·L~(-1)CuO NPs浓度下达到最大值。(2)不同浓度的CuO NPs对紫花苜蓿幼苗根系抗氧化酶活性具有显著影响。随CuO NPs浓度增大,紫花苜蓿幼苗根系中SOD、POD、APX和CAT酶的活性都呈现先增大后减少的趋势,其中,SOD和POD、APX、CAT酶的活性分别是在0.00625、0.0125、0.0625 mol·L~(-1)CuO NPs处理下达到最大,表明这些抗氧化酶在清除根系中的活性氧方面表现出较强的协同性和补偿性。(3)不同浓度的CuO NPs对紫花苜蓿幼苗根系活力具有显著的影响。随着CuO NPs浓度的增加,紫花苜蓿幼苗根系活力逐步升高,这是一种生物适应性应激响应的体现。

Effects of CuO NPs on ROS, Antioxidant Enzyme Activity and Root Activity of the Alfalfa Seedlings

The root is usually the major organ directly contaminated by the environment pollutants such as heavy metal ions and metal oxide nanoparticles.This study explored the effects of CuO NPs on ROS, antioxidant enzyme activities and root activity of alfalfa seedling.The results showed that (1) CuO NPs had significant effects on H2O2 and O· content of the alfalfa seedling root (H2O2, P=0.003;O·, P<0.001).With the increase of CuO NPs concentration, H2O2 and O·contents both firstly increased and then decreased as a whole.Except that H2O2 content of the alfalfa seedling root decreased under the 0.00125 mol·L-1 CuO NPs treatment, all H2O2 and O· contents increased under other CuO NPs treatments compared to the control.And these two indexes both reached the maximum under the 0.0125 mol·L-1 CuO NPs treatment.(2) CuO NPs had significant effects on the antioxidant enzyme activity of the alfalfa seedling root (P<0.001 for all SOD, POD, APX and CAT).With the increase of CuO NPs concentration, the activities of SOD, POD, APX and CAT of the alfalfa seedling root all firstly increased and then decreased.The activities of SOD and POD both reached maximum under the 0.00625 mol·L-1 CuO NPs treatment, while the maximum APX activity value was observed under the 0.0125 mol·L-1 CuO NPs treatment and CAT activity maximum under the 0.0625 mol·L-1 CuO NPs treatment.It is indicated that these antioxidant enzymes underwent a strong collaboration and compensation in clearing up reactive oxygen species of the alfalfa seedling root.(3) CuO NPs had significant effects on the root activity of the alfalfa seedling (P<0.001).With the increase of CuO NPs concentration, root activity of the alfalfa seedling gradually increased, which is a performance of biological adaptation to external stress.