环境相关浓度MC-LR作用对营养生长期水稻生长和抗氧化酶活性的影响

Effects of Microcystin-LR at Environmental Relevant Concentrations on Growth and Antioxidant Enzymes of Oryza sativa L. at Vegetative Stage

以水稻为受试生物,考察暴露浓度为0、0.1、1、10、50μg·L-1的MC-LR分别水培暴露7、15、20、34 d对水稻生长和根部部分酶活性的影响,考察指标包括水稻的株高、根长、鲜重、光合作用系统以及根系中过氧化物酶、谷胱甘肽酶、蛋白磷酸酶和丙二醛活性。34 d实验结束后,相比对照组,0.1、1μg·L-1MC-LR作用下水稻根长分别增加了6.94%和6.06%,而50μg·L-1MC-LR作用下水稻根长显著减少了8.71%。MC-LR暴露能显著诱导水稻抗氧化系统部分关键指标(如POD和GSH),并且随着暴露时间的延长,诱导作用更加明显。0.1μg·L-1MC-LR暴露20、34 d后,相对于对照组POD分别抑制了58.51%和8.09%。50μg·L-1MC-LR暴露34 d后,POD、GSH和PP分别降低了38.52%、45.86%和52.51%。上述结果表明长期暴露在环境相关浓度下的MC-LR可能会对陆生植物产生毒性效应。

In recent years, the worldwide occurrence of cyanobacterial blooms is of great ecological concern because many genera of bloom-forming cyanobaceria are known to produce microcystins. Toxic effects of microcystin-LR(MC-LR)on mammals, birds, and aquatic organ-isms have been widely investigated, but its phytotoxic effects and mechanisms in terrestrial plants remain unclear. In the present study, we examined the growth and development and enzyme activities, including plant height, root length, aboveground biomass, photosynthesizer, and root peroxidase(POD), glutathione(GSH), protein phosphatase(PP)and malondialdehyde(MDA)in rice plants(Oryza sativa L.)ex-posed to 0, 0.1, 1, 10, 50μg·L-1 of MC-LR for 7, 15, 20, and 34 days. Results showed that the root length of rice increased by 6.94%and 6.06%under the exposure of 0.1 and 1μg·L-1 MC-LR, respectively, but reduced significantly by 8.71%under the exposure of 50μg·L-1 MC-LR, compared with the control over the 34 days of the experiment. MC-LR significantly induced the activities of some key indicators in the antioxidant system of rice, such as POD and GSH. The longer exposure time, the more remarkable induction was observed. However, POD was significantly inhibited by 58.51%and 8.09%by 0.1μg·L-1 MC-LR in 20 and 34 days of the experiment, respectively. Applying 50μg·L-1 MC-LR significantly inhibited POD, GSH, and PP by 38.52%, 45.86%, and 52.51%, respectively, after 34 days of the exposure. These results show that MC-LR has toxic effects on terrestrial plants under long time exposure to environmental relevant concentrations.