Alterações do sistema de defesa antioxidativo em plântulas de Stizolobium aterrimum e Canavalia ensiformis expostas ao arsênio

Changes in antioxidative defense system of Stizolobium aterrimum and Canavalia ensiformis exposed to arsenic The present work evaluated the antioxidant responses of Stilozobium aterrimum and Canavalia ensiformis after exposure to arsenic (As). Plants of these two species with the first pair of fully expanded cotyledonary leaves, grown in nutrient solution, pH 5.5, were treated with 0.0 and 1.5 mg.L -1 of As. After 5 days, the effects of As on lipid peroxidation and antioxidant enzymes were measured. Lipid peroxidation increased in both roots and leaves after As treatment, especially in S. aterrimum. Superoxide dismutase (SOD) activity increased in the two parts of the plants of both species with As treatment. Peroxidase (POX) activity, on the other hand, reduced with As treatment in S. aterrimum, but increased in C. ensiformis. Glutathione reductase (GR) increased in roots of both species, mainly in S. aterrimum. GR activity also increased in the leaves of C. ensiformis, but decreased in S. aterrimum. Under the experimental conditions of this study, C. ensiformis was considered to have antioxidant mechanisms slightly more efficient than S. aterrimum against reactive oxygen intermediates (ROIs).