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An increased cadmium content in agricultural soils causes changes in the physiological and biochemical processes in plants, affecting their growth and yield. Different plant species, but also the different cultivars of the same species, widely vary in the terms of cadmium accumulation and tolerance. In this respect, the production of soybean (Glycine max L.) as a leading oil and protein culture is endangered by a low cadmium tolerance. Therefore, the aim of this study is to determine the differences in the biochemical mechanisms of cadmium tolerance in the leaves of three Croatian soybean cultivars (Korana, Ika, and Lucija), which differ in the capacity of cadmium accumulation. The soybean was hydroponically cultivated under the controlled conditions and exposed to cadmium (100 μmol L-1 ) for seven days. As the indicator of oxidative stress, the content of H2O2 and lipid peroxidation levels, expressed in terms of the thiobarbituric acid’s reactive substances, was determined, while an antioxidative status was determined by the activities of the antioxidative enzymes, such as the catalase, ascorbate peroxidase, glutathione peroxidase and guaiacol peroxidase. A cadmium treatment increased the lipid peroxidation levels in the leaves of all three soybean cultivars, indicating the presence of an oxidative stress. Also, the activity of glutathione peroxidase was increased in all cadmium‐treated plants, while other enzymes demonstrated different activity patterns in the investigated cultivars. The cultivar Korana, which manifested the highest level of cadmium accumulation, also manifested the highest level of tolerance with regard to two other cultivars. The most sensitive cultivar, Ika, with a moderate accumulation capacity, manifested the lowest level of an antioxidative response. The biochemical mechanisms of tolerance to a cadmium stress differed in the three investigated soybean cultivars, and a tolerance to cadmium was partly achieved by an increased antioxidative response.

Selenium (Se) is an important microelement with a dual effect ; at lower concentrations it is an essential element for animals, humans and some lower plants, but at higher concentrations, it can become toxic. The aim of this study was to investigate the influence of different concentrations of two selenium forms, selenate and selenite, on the oxidative and antioxidative status of wheat shoots and roots. Wheat grains were exposed to five different concentrations(0.1 mg L-1, 1 mg L-1, 5 mg L-1, 10 mg L-1, 100 mg L-1) of Se in a form of selenite and selenate forseven days. As biomarkers of the oxidative status in wheat, lipid peroxidation (LPO) levels and total H2O2 content were determined. The antioxidative status was determined by total reduced glutathione levels (tGSH), as well as by catalase (CAT) and ascorbate peroxidase (APX) activities. Both Se forms did not cause any significant changes in LPO levels and H2O2 content in shoots, while in roots selenite and selenite induced oxidative stress. tGSH levels in roots and shoot were reduced after the exposure to various concentrations of selenite and selenate relative to their controls. The results showed that both forms of Se decreased CAT activity in roots, while in shoots CAT activity did not change. Furthermore, only the highest concentrations of selenite and selenite increased the APX activity in shoots and roots. In conclusion, the plant response to Se depends on its chemical form, applied concentration and the analyzed part of the plant. The obtained results can serve as a basis for further studies of molecular and biochemical effects of Se on plants.

Anthropogenic activities increased cadmium content in agriculture soils leading to its entry into the food chain, thus causing numerous pathological consequences for the consumers. In addition, cadmium causes changes in physiological and biochemical processes in plants affecting their growth and yield. Different plant species, but also different cultivars of the same species, vary widely in the terms of cadmium accumulation and tolerance. Considering it, production of soybean (Glycine max L.) as a leading oil and protein culture is endangered by low cadmium tolerance. Therefore, the aim of this study is to determine differences in the biochemical mechanisms of cadmium tolerance in leaves of three Croatian soybean cultivars (Korana, Ika and Lucija), which differ in the capacity of cadmium accumulation. As the indicators of oxidative stress, content of H 2 O 2 and lipid peroxidation levels expressed in terms of thiobarbituric acid reactive substances were determined, while antioxidative status was determined by the activities of antioxidative enzymes such as catalase, ascorbate peroxidase, glutathione peroxidase and guaiacol peroxidase. Cadmium treatment increased lipid peroxidation levels in leaves of all three soybean cultivars, indicating presence of oxidative stress. Also, the activity of glutathione peroxidase was increased in all cadmium treated plants, while other enzymes showed different activity patterns in investigated cultivars. Cultivar Korana, that showed the highest level of cadmium accumulation, also demonstrated the highest level of tolerance in regard to other two cultivars. The most sensitive cultivar Ika with moderate accumulation capacity showed the lowest level of antioxidative response. Biochemical mechanisms of tolerance to cadmium stress differed in three investigated soybean cultivars, and tolerance to cadmium was partly achieved by increased antioxidative response.