Enhancement of Plant Regeneration in Lemon Balm (Melissa officinalis L.) with Different Magnetic Field Applications

Abstract

Melissa officinalis L. (lemon balm) is a valuable medicinal and aromatic plant in the Lamiaceae family. Two independent experiments were performed to improve the productivity of the plant regeneration. Firstly, the most efficient in vitro culture system of M. officinalis was determined using 7 different explant types (leaf, petiole, stem, root, axillary buds, shoot buds and cotyledon buds) on medium containing Murashige and Skoog minimal organics (MSMO) medium with different concentrations and combinations of plant growth regulators (PGRs). Micropropagation was obtained only with explants containing meristematic cells (axillary buds, shoot tip buds and cotyledon buds). Lemon balm had a very low regeneration capacity and in the second part of the experiment, enhancement of regeneration was aimed with the applications of different magnetic fields (MFs). Two different MFs (50 and 100 mT) were generated using neodymium block magnets. There was no MF exposure with control treatment. Three different explants (axillary, shoot tip and cotyledon buds) were cultured on media including BA in combination with indole-3-acetic acid (IAA) or naphthalene acetic acid (NAA) with the application of two different MFs at 1 hour duration. As a result, it was determined that MF applications enhanced the regeneration capacity of M. officinalis and the best shoot formation was observed with axillary bud explant cultured in 1.5 mg/L BA at 100 mT MF application for 1 hour duration.