Generation of superoxide anion-radical in leaves of soft wheat (Triticum aestivum L.) under the action of a high-intensity pulsed magnetic field

Background. Currently, the scientific community has accumulated a large amount of data covering the action on biological objects of alternating, constant and pulsed magnetic fields (PMF) of low intensity and induction of the order of B=0.1 Tl as a factor that triggers the oxidative stress and through a series of biochemical reactions leads to the development of a response to the effect of these fields. But the action of high-intensity pulsed magnetic fields with induction from 0.1Tl and higher on biological objects has not been studied to date.

The purpose of this study is to study the effect of high-intensity pulsed magnetic fields with induction from 0.1 Tl on the generation of superoxide anion-radicals in leaves of soft wheat Triticum avestivum L. as a response to this action. 

Materials and methods. The objects of the study were nine-day-old green and etiolated wheat sprouts of soft wheat Triticum avestivum L., grown in distilled water. Processing by a pulsed magnetic field was carried out on a specially designed experimental installation MIU-BIO-5 using a multi-turn inductor for treatment of biological objects in 25 ml test-tubes. The generation of superoxide anion-radicals was recorded spectrophotometrically at a wavelength of 480 nm, based on the donor-acceptor reaction of oxidation of adrenaline to adrenochrome.

Results. The study showed that as a result of exposure to a high-intensity pulsed magnetic field, hereinafter referred as PMF, on green sprouts of soft wheat Triticum avestivum L. after a 60-minute exposure under artificial lighting of 1600 lux, the generation of superoxide anion-radical under the action of the PMF with induction of В=0.53 Tl, В=3.71 Tl and В=5.21 Tl was equal to the control value of 2.17±0.14 μM/g, and under the action of the PMF with induction of В=2.21 Tl, a decrease in the generation to 1.69±0.14 μM/g was noted, which is 1.3 times lower than the control value. In the second experiment with etiolated sprouts, after exposure in the dark, the following decreases in the generation of superoxide anion-radical were observed in relation to the control value equal to 1.53±0.21 μM/g: when exposed to a PMF with induction of В=0.53 Tl, the generation was 1.21±0.14 μM/g, which is 1.3 times less than the control;  when exposed to a PMF with induction of 2.21 Tl, the generation was 1.12±0.16 μM/g, which is 1.4 times less than the control; when exposed to a PMF with induction of В=3.71 Tl, the generation was 1.21±0.24 μM/g, which is 1.3 times less than the control; when exposed to a PMF with induction of В=5.21 Tl, the generation was 1.13±0.08 μM/g, which is 1.4 times less than the control. A third experiment was also conducted to establish the dependence of the value of generation of superoxide anion-radical by green sprouts on time after exposure to the pulsed magnetic field with induction of В=2.21 Tl under daylight of 800 lux. During the third experiment, the following result was obtained: before exposure to the PMF, generation of superoxide anion-radical was 1.69 ±0.24 μM/g; 15 minutes after exposure, an increase in generation was noted to 1.77±0.29 μM/g; after another 15 minutes the generation value remained high and equal to 1.77±0.16 μM/g but there was a tendency towards a decrease; after 60 minutes a decrease in generation to 1.61±0.21 μM/g; and after 24 hours the generation value returned to the control value of 1.69±0.14 μM/g.  The result of the third experiment shows that the PMF with induction of В=2.21 Tl can act as a factor leading to development of oxidative stress in plants. But an hour after exposure, the developed oxidative stress is leveled out due by triggering of antioxidant mechanisms.

Conclusion. The data obtained in the course of three experiments allowed us to put forward the hypothesis that the PMF affects plants as a stress factor, provoking increased generation of superoxide anion-radical and also leads to the activation of the antioxidant system of defense of plants and its strengthening. To confirm the hypothesis put forward, it is proposed to conduct a number of additional experiments with the aim to establish the effect of a PMF on the generation of hydrogen peroxide and the activity of superoxide dismutase enzyme.