Callus induction and plant regeneration in Dorem ammoniacum D., an endangered medicinal plant

Dorema ammoniacum D. Don. (Apiaceae), a native medicinal plant in Iran, is classified as a vulnerable species. Root, hypocotyl, and cotyledon segments were cultured on Murashige and Skoog (MS) (1962) medium supplemented with either 2,4-dichlorophenyoxyacetic acid (2,4-D) or naphathalene acetic acid (NAA), at 0-2 mg l(-1), alone or in combination with either benzyladenine (BA) or kinetin (KN), at 0-2 mg l(-1) for callus induction. The best response (100%) was observed from root segments on MS medium containing 1 mg l(-1) NAA and 2 mg l(-1) BA. The calli derived from various explants were subcultured on MS medium supplemented with BA (1-4 mg l(-1)) alone or in combination with NAA or indole-3-butyric acid (IBA), at 0.2 or 0.5 mg l(-1) for shoot induction. Calli derived from hypocotyl segments showed significantly higher frequency of plantlet regeneration and number of plantlets than the calli derived from root and cotyledon segments. Therefore, MS medium supplemented with 2 mg l(-1) BA and 0.2 mg l(-1) IBA produced the highest frequency of shoot regeneration (87.3%) in hypocotyl-derived callus. The optimal medium for rooting contained 2.5 mg l(-1) IBA on which 87.03% of the regenerated shoots developed roots with an average number of 5.2 roots per shoots within 30 days. These plantlets were hardened and transferred to the soil. The described method can be successfully employed for the large-scale multiplication and conservation of germplasm this plant.