Seedlings of two durum wheat (Triticum durum L.) genotypes, sensitive and tolerant to cadmium, were treated at 3 to 4 leaves stage. The enzymic activities of catalase glutathione s-transferase (GST) and guaiacol peroxidase (GPX) in the case of sensitive genotype significantly increased compared to the control. The activity level of catalase (CAT) and ascorbate peroxidase (APX), however, did not show a significant change. Moreover, the enzymic activity of GPX, GST, CAT and also APX, in the case of cadmium utilization had not a significant change compared to the control. It is argued that the sum of activities of hydrogen peroxide (H2O2)-scavenging enzymes helped control of the amount of the pernicious compound (H2O2) at tolerant genotype. Cadmium stress led to the significant increase of malondialdehyde (MDA) in both durum wheat genotypes, although membrane damage and lipid peroxidation were more severe with regard to sensitive genotype. It follows that the augmentation of H2O2 and the drop in GST activity substantiate further increase in the amount of MDA in sensitive genotype. It is concluded that the activity of H2O2 scavenging enzymes and that of GST enzyme have a crucial role in detoxifying toxic compounds leading to more resistance against salt stress.
