Response of antioxidant enzymes, ascorbate and glutathione metabolism towards cadmium in hyperaccumulator and nonhyperaccumulator ecotypes of Sedum alfredii H.
Hydroponics studies were conducted to investigate the antioxidant adaptations, ascorbate and glutathione metabolism in hyperaccumulating ecotype of Sedum alfredii (HE) exposed to high Cd environment, when compared with its nonhyperaccumulating ecotype (NHE). Exposure to Cd induced a burst of oxidative stress in both ecotypes which was evident by the sharp increase in hydrogen peroxide (H(2)O(2)) contents and lipid peroxidation. Buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, did not affect H(2)O(2) concentrations as well as growth of both ecotypes in the absence of Cd. However, compared with Cd application alone, BSO combined with Cd treatment caused a substantial augmentation of H(2)O(2) accumulation accompanied by a reduction in Cd concentrations in roots and leaves of HE at the end of treatment, which may rule out the possibility that GSH biosynthesis may play an important role as a signal of the stress regulation. No efficient and superior enzymatic antioxidant defense mechanisms against Cd-imposed oxidative stress existed in both NHE and HE, but the essential nonenzymatic components like ascorbic acid (AsA) and GSH played a prominent role in tolerance against Cd. Cadmium stimulated a notable rise in AsA concentration in both ecotypes soon after the application of treatment. A preferential Cd-stress response in HE was suggested to changes in the GSH pool, where acclimation was marked by increased GSH concentrations.
Jin
Xiaofen
X
Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Natural Resources Science, Zhejiang University, Hangzhou 310029, People's Republic of China.
Yang
Xiaoe
X
Mahmood
Qaisar
Q
Islam
Ejazul
E
Liu
Dan
D
Li
Hong
H
D000975:Antioxidants; D001205:Ascorbic Acid / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000494:pharmacology*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D031963:Sedum / Q000187:drug effects* / Q000201:enzymology*; D012989:Soil Pollutants / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D012989:Soil Pollutants; D002104:Cadmium; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; C121048:guaiacol peroxidase; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D005978:Glutathione; D001205:Ascorbic Acid