THE EFFECTS of HEAVY METAL APPLICATIONS on ANTIOXIDANT DEFENCE ACTIVATION in BARLEY and WHEAT VARIETIES

Abstract

Heavy metals are known as agents for oxidative stress by formation of reactive oxygen species and accumulated on the earth. This accumulation can than be transported via food chain to humans and causes some more serious health problems. As a multicellular higher organisms, plants are the first stop for heavy metal accumulation during this traffic. Therefore, plants are not only the vehicle of this transportation, but also another affected organisms together with animals and humans, due to their lowered self productivity. However, as antioxidant defence systems play a crucial defence against oxidative stress, these responses could be used as early biomarkers of heavy metal toxicity in plants. Based on this, we have examined whether antioxidant defence responses are reliable indicators for the toxicity of heavy metals cadmium and lead in different crop plants within this study. By using the seeds of Hordeum vulgare cv. Çıldır and Triticum aestivum cv. Gerek, different single and combined concentrations of CdCl2 and PbCl2 treatments were applied to investigate glutathione (GSH), protein contents and glutathione S-transferase (GST) activities in the roots and shoots of these mentioned varieties. Our results shown that, heavy metals had an effect on the tested parameters and variability in results reflect the differences in the rate of metabolism with regard to heavy metals between varieties. On the other hand, due to the high GSH and GST values observed in the studied plants, it should be mentioned that they are generally adaptable to stress conditions with regard to applied heavy metals in the study.