Pedosphere 27(2): 262--273, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Phyto-toxicity of chromium in maize: Oxidative damage, osmolyte accumulation, anti-oxidative defense and chromium uptake
Shakeel Ahmad ANJUM1,2, Umair ASHRAF3,4, Imran KHAN2, Mohsin TANVEER5, Muhammad SHAHID2, Abdul SHAKOOR2,WANG Longchang1
1College of Agronomy and Biotechnology, Southwest University/Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing 400716 (China)
2 Department of Agronomy, University of Agriculture, Faisalabad 38040 (Pakistan)
3 Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou 510642 (China)
4 Scientific Observing and Experimental Station of Crop Cultivation in South China, Ministry of Agriculture, Guangzhou 510642 (China)
5 School of Land and Food, University of Tasmania, Hobart 7005 (Australia)
      Agricultural production systems are immensely exposed to different environmental stresses in which heavy metal stress receives serious concerns.This study was conducted to explore the deleterious effects of different chromium (Cr) stress levels, i.e., 0, 30, 60, 90, 120, and 150 upmumol L-1, on two maize genotypes, Wandan 13 and Runnong 35.Both genotypes were evaluated by measuring their growth and yield characteristics, Cr accumulation in different plant tissues, alterations in osmolyte accumulation, generation of reactive oxygen species (ROS), and anti-oxidative enzyme activity to scavenge ROS. The results showed that Cr stress decreased the leaf area, cob formation, 100-grain weight, shoot fresh biomass, and yield formation, while Cr accumulation in different maize tissues was found in the order of roots > leaves > stem > seeds in both genotypes. The increased Cr toxicity resulted in higher free proline, soluble su-gars and total phenolic contents, and lower soluble protein contents.However, enhanced lipid peroxidation was noticed in the forms of malondialdehyde, hydrogen peroxide (H2O2) and thiobarbituric acid reactive substance accumulation, and electrolyte leakage.The hyperactivity of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, especially glutathione peroxidase and glutathione reductase indicated that these anti-oxidative enzymes had a central role in protecting maize from Cr toxicity, especially for Wandan 13. Moreover, higher uptake and less translocation of Cr contents into the grains of Wandan 13 implied its importance as a potential candidate against soil Cr pollution.
Key Words:  agronomic characteristics, anti-oxidative enzyme activity, Cr accumulation, Cr translocation, heavy metal stress, reactive oxygen species
Citation: Ahmad, A., Umair, A., Imran, K., Mohsin, T., Muhammad, S., Abdul, S. and Wang, L. 2017. Phyto-toxicity of chromium in maize: Oxidative damage, osmolyte accumulation, anti-oxidative defense and chromium uptake. Pedosphere. 27(2): 262-273.
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