Abstract
BackgroundMycotoxins are among the environmental stressors whose oxidative action is currently widely studied. The aim of this paper was to investigate the response of seedling leaves to zearalenone (ZEA) applied to the leaves (directly) and to the grains (indirectly) in tolerant and sensitive wheat cultivars.ResultsBiochemical analyses of antioxidant activity were performed for chloroplasts and showed a similar decrease in this activity irrespective of plant sensitivity and the way of ZEA application. On the other hand, higher amounts of superoxide radical (microscopic observations) were generated in the leaves of plants grown from the grains incubated in ZEA solution and in the sensitive cultivar. Electron paramagnetic resonance (EPR) studies showed that upon ZEA treatment greater numbers of Mn - aqua complexes were formed in the leaves of the tolerant wheat cultivar than in those of the sensitive one, whereas the degradation of Fe-protein complexes occurred independently of the cultivar sensitivity.ConclusionThe changes in the quantity of stable, organic radicals formed by stabilizing reactive oxygen species on biochemical macromolecules, indicated greater potential for their generation in leaf tissues subjected to foliar ZEA treatment. This suggested an important role of these radical species in protective mechanisms mainly against direct toxin action. The way the defense mechanisms were activated depended on the method of the toxin application.
Highlights
Mycotoxins are among the environmental stressors whose oxidative action is currently widely studied
In our earlier studies Fe (III) species, the form of Fe ions determined by Electron paramagnetic resonance (EPR) method in standard conditions, were analyzed based on differences in the character of their signals registered at different temperatures
In our earlier studies we found that zearalenone (ZEA) may be localized in the chloroplasts and may interact with these organelles [10, 11]
Summary
Mycotoxins are among the environmental stressors whose oxidative action is currently widely studied. The study of photosynthesis, with its redox reactions including changes in the oxidation state of metal ions or formation of radical species are carried out by different methods. Under Fe deficiency, ferritin can serve as Fe donor, and under Fe excess as its accumulator [4] This protective property of ferritin is important, as high concentrations of iron ions can evoke the oxidative stress and lead to oxidative damage of proteins and membrane lipids. In our earlier studies Fe (III) species, the form of Fe ions determined by EPR method in standard conditions, were analyzed based on differences in the character of their signals registered at different temperatures. Variations in the content and character of manganese ions, occurring upon oxidative stress, were studied, based on EPR spectra [5]. Signal intensities of these manganese aqua-complexes were different in the spectra of each genotype, which allowed us to distinguish them from one another [5]
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