An efficient in vitro shoot regeneration from immature inflorescence and ex vitro rooting of Arnebia hispidissima (Lehm). DC. - A red dye (Alkannin) yielding plant.

Arnebia hispidissima, which belongs to the family Boraginaceae, is an important medicinal and dye yielding plant. The alkannin, a red dye, are root-specific secondary metabolites of A. hispidissima. Shoots were regenerated from callus derived from immature inflorescence explants obtained from field grown plants. MS medium containing 4.52 μM 2, 4-D and 3.33 μM BAP was found to be most effective for the proliferation of callus, induced on medium containing 4.52 μM 2, 4-D. Maximum number (43.1 ± 0.25) with average length (5.2 ± 0.23) of shoots regenerated when callus was transferred to MS medium supplemented with 1.11 μM BAP, 1.16 μM Kin and 0.57 μM IAA. About 75.5 % of in vitro regenerated shoots were rooted on half-strength MS medium supplemented with 9.84 μM of IBA and 200 mg l(-1) of activated charcoal. In comparison to in vitro, higher percent (90.2 %) of shoots were rooted under ex vitro conditions when treated with IBA (0.98 mM) for 5 min. Plantlets rooted in vitro as well as ex vitro were acclimatized successfully under the green house conditions. Ex vitro rooted plants exhibited higher survival percentage (75 %) as compared to in vitro rooted plantlets (60 %). Present study may be applicable in the large-scale root-specific red dye (alkannin) production via root induction under ex vitro condition.