In vitro propagation of Eulophia nuda Lindl., an endangered orchid

An in vitro propagation and tuberization method was successfully established for Eulophia nuda Lindl., an endangered orchid of Aravalli hills. Shoot buds were induced from tuber explants (1 cm cut pieces) on Murashige and Skoog (MS) medium containing 44.4 μM 6-benzyladenine (BA) and additives (283.8 μM ascorbic acid, 67.8 μM adenine sulphate, 143.5 μM arginine and 118.9 μM citric acid). After excision of newly formed shoots, explants were successively transferred to MS medium with 22.2 μM BA and additives for shoot multiplication up to three passages. Further shoot multiplication and tuberization was achieved, by subculturing of in vitro-formed shoots, on MS medium containing 8.88 μM BA, 4.68 μM Kinetin (Kn) and additives. Shoot multiplication was influenced by cytokinin type, concentration and combinations. Shoots with tubers were successfully rooted in vitro and ex vitro. Shoots were treated with 2.46 mM indole-3-butyric acid (IBA) for 4 min for ex vitro rooting. Plantlets were acclimatized in the greenhouse conditions in bottles containing soilrite. Acclimatized plantlets were transferred to the earthen pots containing soil as a mixture of clay, sand and vermicompost (1:1:1). In vitro tuber formation of E. nuda was high compared to the ex vitro/natural conditions. This is the first report for in vitro propagation and tuberization of E. nuda. The protocol developed can be utilized for both large scale plant production and conservation of germplasm of this species.

► First report on in vitro propagation and tuberization of Eulophia nuda. ► Maximum tuber formation were on MS, additives, 8.88 μM BA, 4.68 μM Kinetin (Kn). ► The tuber formation of E. nuda under the in vitro conditions is high. ► Protocol is useful for large scale plant production and conservation.