Lead Toxicity Induced Growth and Antioxidant Responses in Luffa cylindrica Seedlings

In vitro culture experiment was conducted to investigate the growth and antioxidant changes in activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and phenylalanine ammonium-lyase (PAL) in Luffa cylindrica seedlings exposed to lead toxicity. The fresh weights in the cotyledons, hypocotyls and radicles decreased gradually with increasing lead concentrations between 200 and 800 mu M. SOD activity in the cotyledons, hypocotyls and radicles increased significantly with increasing lead concentrations up to 400, 200 and 800 mu M, respectively. POD activity in the cotyledons, hypocotyls and radicles reached peaks at lead concentrations of 400, 200 and 400 mu m, respectively. CAT activity in the cotyledons, hypocotyls and radicles showed the highest increments at lead concentrations of 400, 800 and 800 mu M, respectively. PAL activity in the cotyledons, hypocotyls and radicles increased significantly with the rising lead concentrations up to 800, 800 and 200 mu M. Electrophoresis anaylsis showed that different patterns of POD isoenzymes depend on lead concentrations and tissue types, and the staining intensities of the isoenzymes are well consistent with the changes of the activity assayed in solutions. Our results showed that increased SOD, POD, CAT and PAL activity may be associated with the tolerance capacity of L. cylindrical to protect the plant from oxidative damage. (C) 2010 Friends Science Publishers