Metabolic changes in tobacco cells after exposure to static magnetic field is mediated by hydrogen peroxide

Plant cells metabolism is known to undergo considerable reprogramming in response to static magnetic field (SMF). In the present research changes of metabolism induced by SMF and the underlying mechanism(s) were investigated in suspension-cultured tobacco (Nicotiana tabacum cv. Barley 21) cells. Considering the potential role of SMF in production of hydrogen peroxide and the role of Ascorbic acid (Asc.) as a strong scavenger of H2O2, tobacco cells were exposed to SMF alone, Asc. (40 µM), SMF+Asc., and control (no SMF, no Asc.) in the experiment. Sugars and amino acids were monitored by HPLC, components of redox system were measured by spectrophotometer, and expression of genes was evaluated by RT-PCR. Exposure to SMF decreased the adenosine triphosphate, glucose, fructose, and sucrose contents but increased hydrogen peroxide, nitric oxide, hydroxyl radical, proline, and reduced glutathione (GSH). SMF also increased the gene expression and activity of catalase, compared to the control group. Moreover, the exposure to SMF increased the contents of phenylalanine and tyrosine, elevated the gene expression and activity of phenylalanine ammonia-lyase, and subsequently increased soluble phenolic compounds. In the groups treated with Asc., all above-mentioned parameters reduced except for nitric oxide and hydroxyl radical contents. The rate of membrane lipid peroxidation also increased in Ascorbate-pretreated cells. The results suggested that changes in primary and secondary metabolic pathways in SMF-treated tobacco cells after were mediated by H2O2.