A comparative study of heavy metal accumulation and antioxidant responses in Jatropha curcas L

Abstract

Jatropha curcas L. commonly known as physic nut or purging nut, is a drought resistant shrub belonging to the family Euphorbiaceae, was analyzed for its accumulation capacity of heavy metals such as lead (Pb), cadmium (Cd) and chromium (Cr). Bioassay was conducted by raising the plant by vegetative propagating the stem cutting in varying concentration of respective heavy metals. The metal concentration in the bioparts of experimental plant revealed that the treated plants accumulated enormous quantity of lead, cadmium and chromium as compared to control plant. The effect of heavy metal stress on antioxidant activity in of J. curcas was investigated. The activity of enzymatic antioxidant such as superoxide dismutase (SOD; E.C. 1.15.1.1) catalase (CAT: EC 1.11.1.6) polyphenol oxidase (PPO; EC 1.14.18.1), peroxidase (POX; E.C. 1.11.1.7) and, phenylalanine ammonia lyase (PAL; E.C.4.3.1.5) were estimated and showed profound variations in response to heavy metal stress from the control plants. Non enzymatic antioxidants such as proline increased with heavy metal concentration and phenol concentration fluctuates. Carotenoids and chlorophyll content found to be reduced with increasing heavy metal concentration. Jatropha curcas L. was capable of self protection against multi-metal stress through activation of various enzymatic and non enzymatic antioxidants.