Growth and antioxidant responses in Jatropha curcas cotyledons under lead stress.

Jatropha curcas embryos were grown in vitro to observe the effects of lead on cotyledon responses. The cotyledon biomass increased initially and then decreased with increasing lead concentration. The SOD activity increased gradually up to 200 microM and then decreased. The POD activity showed a similar trend. The CAT activity was increased at all lead concentrations, the highest activity being observed at 200 microM. However, the PAL activity was inhibited significantly except for 100 microM. Anaylsis by electrophoresis suggested a significant correlation between lead concentration and patterns of SOD, POD and CAT isoenzymes, and these results were consistent with changes of the antioxidant enzyme activities as assayed in solution.