Protective Reactions of Seedlings Against Systemic and Local Zearalenone Application to Tolerant and Sensitive Wheat Varieties – Epr Studies 

Abstract BACKGROUNDAmong the environmental stressors, which oxidative action is currently widely studied, are mycotoxins. The aim of presented studies was to investigate the response of leaves of seedlings to zearalenone (ZEN) applied directly to leaves and to grains (indirectly) of tolerant and sensitive wheat cultivars.RESULTS Biochemical analyses of antioxidative activity were performed for chloroplasts and showed the similar decrease of this activity independently of plant sensitivity and the way of ZEN application. On the other hand, higher amounts of superoxide radicals (microscopic observation) were formed in leaves of plants grown from grains incubated in solution of ZEN and in sensitive variety. Electron paramagnetic resonance (EPR) studies showed that upon ZEN treatment larger amount of Mn - aqua complexes was formed in leaves of tolerant wheat cultivar than in those of sensitive one whereas the degradation of Fe-protein complexes occurred independently of the sensitivity of plant varieties. CONCLUSIONThe changes in the quantity of organic stable radicals, which were formed by stabilizing reactive oxygen species on biochemical macromolecules, pointed to the higher ability to their generation in leaf tissues subjected to foliar ZEN treatment indicating the important role of these radical species in protective mechanism mainly against direct toxin action. The way of activation the defense mechanisms depended on the method of applications toxin.