Effects of Low Frequency Electromagnetic Radiation on Lemna minor growth parameters and generation of point mutations at GPx, CAT and APx genes

Abstract

Development of new technologies distributing electric power from power stations to our homes through a network of cables and wires, including numerous electric devices at working places and home environment become a source of electromagnetic radiation (EMR) much stronger than EMR of natural origin. To provide a better understanding of the impact of the EMR of anthropogenic origin on living organisms, we investigated the long-term effects of EMR on Lemna minor. In this study, plants of the L. minor laboratory clone were exposed to low frequency (50 Hz) electromagnetic radiation (LF EMR) growing clones in Petri dishes placed on the coils initially generating magnetic flux (MF) of 1 µT for first three weeks, 2 µT until 12th week and after 12th week of the experiment MF was enhanced up to 300 µT. We exam-ined the response of the plants by sequencing DNA fragments that included promoter, intron, and exon regions of ascorbate peroxidase (APx), glutathione peroxidase (GPx), and catalase (Cat) genes) as well measured growth parameters growth intensity, frond area, and number of fronds. Comparison of growth parameters of L. minor clones exposed to 2 µT and 300 µT magnetic flux revealed positive effect stimulating growth of experimentally affected plants at 2 µT After the first 14 weeks of treatment, the growth parameters were lower in the directly exposed by LF EMR group than in the group grown distantly from the source of EMR. However, after 18 weeks from the beginning of the experiment no significant difference was observed between two groups of L. minor including directly and indirectly affected by LF EMR plants. Moreover, the signals of the impact of LF EMR on the plants as rising of new point mutations were detected. The significantly enhanced number of variations in DNA sequences of L. minor clones directly affected by LF EMR in comparison to indirectly affected clones were revealed at the introns of APx (P = 0.011), GPx (P = 0.009), and Cat (P = 0.044) genes starting from the 10th week of the experiment In conclusion, the comparison of DNA sequencing data together with measurements of growth parameters revealed differences in response at molecular and physiological levels of directly and indirectly affected L. minor clones providing evidence that response to the impact of LF EMR depended on the prolongation of the impact and the magnetic flux density.