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Effects of Microcystin-LR at Environmental Relevant Concentrations on Growth and Antioxidant Enzymes of Oryza sativa L. at Vegetative Stage
Received:June 26, 2014  
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KeyWord:microcystin-LR;rice;growth;photosynthesis;enzymatic;activity
Author NameAffiliationE-mail
ZHANG Min-min Nanjing University of Information Science & Technology, College of Environmental Science and Engineering, Nanjing 210044, China
Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China 
 
JIANG Jin-lin Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China jjl@nies.org 
ZHOU Jun-ying Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China zhjynies@163.com 
SHAN Zheng-jun Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China  
BU Yuan-qing Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China  
XU Wei-li Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing 210042, China  
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Abstract:
      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 organisms 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.) exposed to 0, 0.1, 1, 10, 50 μg·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 1 μg·L-1 MC-LR, respectively, but reduced significantly by 8.71% under the exposure of 50 μg·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 0.1 μg·L-1 MC-LR in 20 and 34 days of the experiment, respectively. Applying 50 μg·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.