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| Effects of lead polluted water on activities of superoxide dismutase, peroxidase and ultrastructure in leaves of Trapa bicornis seedlings. |
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Abstract To investigate the lead toxicity on water caltrop (Trapa bicornis Osbeck), activities of superoxide dismutase (SOD) and peroxidase (POD), ultrastructure in leaves of seedlings, treated with different concentration of lead solution, were analyzed. The SOD activity was initially stimulated and then inhibited with increasing lead concentration. Under high lead concentration (15 mg/L and 20 mg/L), POD activity presented the same tendency as that in SOD analysis, but it increased continually in lower series of lead concentration (5mg/L and 10 mg/L). Ultrastructural damage in the leaf cells, treated with 20 mg/L lead, was observed under transmission electron microscopy. Moreover, the total DNA extracted from these lead-treated leaves showed a remarkable smear by agarose gel electrophoresis, indicating that the cell death was distinct from the so-called programmed cell death (PCD) characterized by a DNA ladder. Based on these results, lead stress exert its toxicity on the seedlings through multiple cross pathways, including inhibition of physiological and biochemical function, damage of celluar structures at molecule and organelle levels.
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Received: 15 July 2008
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