Static magnetic field promotes faster germination and increases germination rate of Calotropis procera seeds stimulating cellular metabolism

Studies have reported responses of plants to magnetism although the underlying mechanisms are not established. Here it is reported biochemical responses of seeds of Calotropis procera, a noncultivated species, when exposed to static magnetic field (MF). Screening of the MF effect on seed germination was performed (0; 0.5; 1.0; 2.0 mT) and then the best response to field intensity (2 mT) was fixed in further analyses. Seeds were germinated for 5 days under 2 mT or seeds were exposed to 2 mT for 5 days and then germinated. Treatments were compared to seeds germinated without MF. MF reduced the time for seed germination (two days) and increased germination rate (65%-90%). This was accompanied by higher fresh and dry matter. Activity of catalase was not altered. Activity of POX increased and that of APX decreased in seeds after MF exposure, indicating oxidative unbalance. The increased contents of hydrogen peroxide and malondialdehyde were also indicators of oxidative stress. DNA integrity was preserved, while soluble protein and DNA quantity increased, compared to the control. Confocal analysis of seed tissues stained with propidium iodide suggested cellular proliferation stimulated by MF. Proteomics and bioinformatics analysis corroborated these data with up regulated protein involved in energetic and protein metabolism. These observations suggested increased cellular metabolism in seeds submitted to MF. It is concluded that MF accelerated the seed germination of Calotropis procera boosting seed metabolism. In this regard, MF might play a role of a mitogen-like inducer.