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 underlying mechanism(s) was investigated in suspension-cultured tobacco (Nicotiana tabacum cv. Barley 21) cells. 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). Treatment with SMF also increased the gene expression and activity of catalase, compared to the control group. Exposure to SMF also increased the contents of phenylalanine and tyrosine, elevated the gene expression and activity of phenylalanine ammonia-lyase, and subsequently increased soluble phenolic compounds. Pretreatment of the cells with 40 µM sodium ascorbate reduced all above mentioned parameters except for nitric oxide and hydroxyl radical contents. The rate of membrane lipid peroxidation was also increased in ascorbate-pretreated cells. The results suggest a crucial role for H2O2 in triggering changes in primary and secondary metabolic pathways which result in alleviation of stress of SMF in tobacco cells.