ANTIOXIDATIVE RESPONSE OF MAIZE TO SALT-INDUCED STRESS

The aim of the work was to examine the influence of high concentrations of NaCl on protein concentration and the antioxidant system of maize roots and leaves. Maize plants (hybrid ZP 555) were treated with sodium chloride (NaCl) in concentrations of 50 and 150 mM for six days, hydroponically. Among the antioxidant parameters, the concentration of glutathione (GSH) and the activity of antioxidant enzymes: Class III peroxidase (POX, EC 1.11.1.7), ascorbate peroxidase (APX EC 1.11.1.11), and catalase (CAT, EC 1.11.1.6) were determined. When treated with 50 mM NaCl, the concentration of proteins in the leaves and roots decreased while at 150 mM NaCl the concentration of proteins increased but only in the leaves. An increase in GSH concentration was detected at both concentrations of NaCl in the leaf, and in the root only at 50 mM NaCl, compared to the control. The activity of POX increased significantly only in the leaves treated with the higher concentration of NaCl, while at lower concentrations it decreased, in both leaves and roots. Five rPOX isoforms were detected by native gel electrophoresis in the control, while no rPOX5 isoform was detected in the treated samples. Two lPOX isoforms were detected in both control and treated samples. Native electrophoresis showed the presence of one CAT isoform only in leaves, in both control and treated samples. The highest CAT activity was measured at the lower NaCl concentration. Based on the obtained results, it can be concluded that salinity changes the antioxidant system in the leaves and roots of maize. Also, based on the measured parameters, it can be concluded that the ZP 555 hybrid has a moderate tolerance to the tested salinity levels.