Resposta de crotalaria juncea a exposição ao niguel

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The contamination of the environment with heavy metals has become a world-wide problem. Heavy metals can have direct effects on human health and decreases agricultural yields. In the presence of Nickel (Ni), plant growth and the net photosynthetic rate have been shown to be significantly reduced, even at low concentrations. Moreover, Ni can also inhibit the activity of several groups of enzymes and metabolism. The effects of the Ni on the activies of the antioxidant enzymes and metabolism were investigated in C.juncea seedlings. Enzymatic assays for Catalase (CAT) Glutathione Reductase (GR) and Superoxide Dismutase (SOD) were carried out. Response patterns for CAT and GR were similar with low values in the roots and increased activity in the shoots. A significant increase in CAT and GR activity in the shoots suggests that these enzymes play a role in the detoxification process, of reactive oxygen species (ROS) produced by the induced Ni stress, possibly by subquesent dismutase. On the other hand, the activity of SOD was stimulated in the roots, and decreased in the shoots. To gain insight into the response of C. juncea seedlings to the oxidative damage induced by excess Ni, were conducted studies of Malondialdehyde (MDA). It was evident that Ni induced an increase an lipid peroxidation in the shoots during the studied period. The Ni concentration in shoots and roots was determined for C. juncea and demonstrated an increase in the concentration of Ni in the roots, however the shoots did not present an accumulation. Further experiments were carried out on total free amino acids. It was observed that Ni treatment did not cause any change in the accumulation of total free amino acids in the roots. The results suggest that in C. juncea seedlings did not exhibit any major variation following Ni treatment. Key words: Antioxidant enzymes, Amino acids, C. juncea, Nickel, Environmental Pollution

ASSUNTO(S)

aminoacidos amino acids poluição enzimas pollution enzymes crotalaria niquel nickel

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