Affiliations: Lab for Wetland Process and Environment, Changchun
Institute of Geography, The Chinese Academy of Sciences, Changchun130021
,China; E-mail: yuguoying@mail. ccig. ac. cn
Abstract: Physiological responses on the bases of activities of antioxidant
enzymes: peroxidase, catalase, superoxide dismutase and glutathione reductase
as well as estimation of total protein, lipid peroxidation and thiols in the
form of iprotein, non-protein, glutathione and phytochelatin measured in
growing seedlings of paddy, Oryza sativa L. , from day 2 to 8 were compared
following treatment of seeds for 5h with oxidative agents, paraquat 5 x 10^-5,
10^-4, 10^-3 mol/L, H_2O_2 10^-3, 5 x 10^-3, 10^-2 mol/L, and CdCl_2 10^-5,
10^-4, 5 x 10^-3 mol/L. A significant induction of all antioxidant enzymes
along with an increase in the levels of protein, lipid peroxidation and
glutathione was noted in response to oxidative stress, CdCl_2 induced
significant peroxidase and catalase activities but not superoxide dismutase. In
a marked contrast from oxidative stress, CdCl_2 decreased glutathione reductase
activity as well as glutathione levels but increased phytochelatin level. The
different physiological responses thus underlined the crucial involvement of
glutathione and phytochelatin in the oxidative and heavy metal-induced adaptive
responses respectively.
