RESPONSES OF THE ORGANIC ACID LEVEL AND THE ANTIOXIDATIVE ENZYME ACTIVITY OF BARLEY SEEDLINGS IN THE EARLY PHASE OF NICKEL STRESS

Changes of the activity of antioxidative enzymes (ascorbate peroxidase-APX; guaiacol peroxidase-OX) and organic acid-OA (oxaloacetate-Ox, citrate-Cit, malate-Mal, succinate-Suc and fumarate-Fum) content were investigated in barley leaves during a week of 0, 300 mu M nickel-Ni treatment in order to clarify the processes occurring during the early phase of Ni exposure as an abiotic stress agent. We concluded that after one day of 300 mu M Ni exposure, only malate rose considerably, by 260 %, the rest of the OAs rose only slightly. The activity of POX did not change, APX however rose both in roots and in leaves indicating ROS formation and that this enzyme plays part of the detoxification processes in the early phase of Ni exposure.