Protective role of pulsed magnetic field against salt stress effects in soybean organ culture

Pulsed magnetic field (PMF) effects on soybean plant regeneration under salt stress conditions were investigated. Seedlings were raised from seeds pre-treated with 0.1, 1.0, 10.0 and 100.0Hz PMF. Cotyledonary nodal (CN) explants from PMF exposed and unexposed seedlings were cultured in media containing different concentrations of NaCl (0, 10, 20, 30 and 40mM). In CN explants from unexposed seedlings, increasing salt concentration progressively suppressed the regeneration and development of shoots and roots. Plantlets were regenerated only on medium containing 0, 10, 20 and 30mM NaCl. The highest dose of NaCl (40mM) failed to induce shoot formation and strongly reduced the number of roots which also exhibited reduced length. Cotyledonary nodal explants from PMF exposed seedlings, cultured at 10, 20 and 30mM NaCl, exhibited a higher frequency of shoot and root regeneration, as well as a higher number and length of shoots and roots compared to unexposed ones, with 1.0Hz frequency resulting the most efficient in promoting regeneration. At 40mM NaCl, the promotive effect of different PMFs frequencies was related to the induction of a greater number of roots and the enhancement of root length. Our results suggest that PMF pre-treatment could help the regeneration of soybean under salt stressed condition.