Rapid plant regeneration from nodal explants of Spilanthes acmella (L.) Murr. - an endangered medicinal plant

Excised nodal explants of Spilanthes acmella (L.) Murr., ‘Toothache Plant’ proliferate rapidly in vitro on MS medium containing 0.5- 2.0 mg/l of BAP. Rapid and prolific shoot proliferation occurred. Regenerated shoots vary considerably in size (3-10 cm long) and relative stage of development, with some (50%) producing adventitious roots without transferal to a separate rooting medium. With maximum possibility of adventitious roots induction was induced from middle order nodes (3 rd to 5 th node from apex) obtained from 3 months old in vivo plant on full-strength MS medium supplemented with 1.0 mg/l BAP under the photoperiod of 18-h. The possibility of adventitious roots induction directly from regenerated shoot was greatly influenced by the concentration of BAP, photoperiod, age of donor plant and nodal position on stem.