Exogenous Elicitors Driven optimization: a boon for in vitro propagation and acclimatization of Euphorbia milii plant

Background Euphorbia milii is a flowering ornamental plant that plays an important role in folk medicine. It has a variety of therapeutic effects due to its high content of many active compounds. This research presents a simple protocol for micropropagation of Euphorbia milii and studies the effect of certain elicitors on shoot multiplication. Root induction and the adaptation stage in vitro were studied. Results Nodal stem segments from regenerated shoots were cultured on MS medium containing different levels of benzyladenine (BA) (0, 0.5, 1, 1.5 mg·L ^− 1 ). Regenerated microshoots were cultured on different rooting media including MS-salt-free, ¼ MS salts, ½ MS salts, and full-strength MS salts. Biotic elicitors (malt extract, yeast extract and peptone) and abiotic elicitors (salicylic acid, abscisic acid and gibberellic acid) at different concentrations were added to MS medium fortified with 1 mg·L ^− 1 BA. The results showed that 1 mg·L ^− 1 BA was the optimal treatment for shoot multiplication. Full-strength MS medium produced the highest number of roots. In the case of biotic elicitors’ effect on shoot multiplication, malt extract (400 mg·L ^− 1 ) was produced the highest number of shoots per explant and shoot length followed by yeast extract at 3 g·L ^− 1 concentration. In the case of abiotic elicitors’ effect, abscisic acid (0.5 mg·L ^− 1 ) gave both the highest number of shoots per explant and shoot length, followed by salicylic acid at 2 mg·L ^− 1 . The plantlets were successfully acclimatized by transferring them into a potting mixture of peat moss: sand in equal proportion with 100 percent survival was observed. Conclusions Stem nodal explants were the optimal source for proliferation and rapid in vitro propagation of Euphorbia milii on a large scale. Biotic and abiotic elicitors had a significant effect on plant growth; especially, malt extract and abscisic acid which are the preferable elicitor for shoot multiplication. Plants derived from the treatment of 1.0 mg·L ^− 1 BA + 400 mg·L ^− 1 ME showed good growth and flowering performance in nursery pots.