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Heavy Metal Accumulation and Antioxidative System Responses of Plagiomnium acutum Under Combined Cadmium and Lead Stresses
Received:November 11, 2014  
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KeyWord:Plagiomnium acutum;combined cadmium and lead stress;accumulation;antioxidative system;response
Author NameAffiliationE-mail
TIAN Xiang-rong College of Biology and Enviromental Science, Jishou University, Jishou 416000, China
Key Laboratory of Plant Resources Conservation and Utilization(Jishou University), College of Hunan Province, Jishou 416000, China 
 
WU Hao College of Biology and Enviromental Science, Jishou University, Jishou 416000, China  
LI Jing College of Biology and Enviromental Science, Jishou University, Jishou 416000, China
Key Laboratory of Plant Resources Conservation and Utilization(Jishou University), College of Hunan Province, Jishou 416000, China 
 
LI Zhao-yang College of Biology and Enviromental Science, Jishou University, Jishou 416000, China
Key Laboratory of Plant Resources Conservation and Utilization(Jishou University), College of Hunan Province, Jishou 416000, China 
ligz0000@126.com 
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Abstract:
      Moss, as a pioneer plant of the whole ecosystem, possesses several special physiological characteristics to adapt the severe environment, such as extreme cold and heavy metal contamination. Here, a submerging culture experiment was designed to explore heavy metal accumulation and antioxidative responses of Plagiomnium acutum under combined lead and cadmium stresses. The presence of lead obviously inhibited absorption of cadmium under combined stresses. Compared with 20 mg·L-1 lead treatment, cadmium absorption were reduced by 30.1% and 78.4% under low cadmium treatment(2 mg·L-1), and by 35.0% and 86.9% under high cadmium treatment(50 mg·L-1), by 50 mg·L-1 and 100 mg·L-1 lead, respectively. The content of lipid peroxidation final product, malondialdehyde(MDA), increased with elevated combined stresses. The highest MDA level was 7162% over the control. Superoxide dismutase(SOD) activity and proline content were the highest under the greatest combined stress, which were respectively 237.4% and 2049% over the control. The SOD activities(R2=1, 0.935, 0.481) and proline content(R2=0.955, 0.927 and 0.999) was mainly related to lead. On the contrary, activities of peroxidase(R2=0.451, 0.997 and 0.976) and catalase(R2=0.726, 0.850 and 0.725) were negatively impacted mainly by cadmium under combined stresses. In summary, (1) lead can inhibit cadmium absorption in a dose-effect manner; (2) the main toxicological reaction should be cellular oxidative damage caused by cadmium; and (3) the preliminary source of cell oxidative damage in Plagiomnium acutum under combined stresses is the accumulation of peroxide from weakened ability of peroxide scavenging.