High frequency direct plant regeneration, micropropagation and Shikonin induction in Arnebia hispidissima

Abstract

The data presented herein reports a rapid and efficient method for direct plant regeneration at high frequency without intervening callus formation from shoot tip (93%) and nodal segment (60%) cultured on MS media supplemented with 0.5 mg l⁻¹ KIN, 0.25 mg l⁻¹ BAP, 0.1 mg l⁻¹ IAA and 100 mg l⁻¹ CH. Conversely, leaf and internodal explants were poorly responsive. Adventitious shoot buds arose not only from the cut ends but all along the surface of the explants leading to the formation of clusters with multiple shoots. Multiple shoots upon transfer to MS media supplemented with 2.0 mg l⁻¹ IBA induced efficient rooting (80%). In vitro flowering was observed when tissue culture-raised plantlets were maintained for extended period in culture. Shikonin was induced in roots of regenerated plants which often exudates in the culture medium was quantified spectrophotometerically by recording absorbance at 620 nm and estimated to be 0.50 mg g⁻¹ fresh weight of tissue at the end of the 50 days of culture. The regenerated plants were successfully acclimatized, hardened, and transferred to soil in green house for micropropagation. The protocol developed here will be very useful for the supply of Arnebia hispidissima all year as a raw product necessary for obtaining Shikonin for the cosmetic, dyeing, food, and pharmaceutical industries.