An efficient and economic method for in vitro propagation of Arnebia euchroma using liquid culture system

Abstract

Arnebia euchroma Royle (Johnston) (Boraginaceae), a rich source of shikonin derivatives, is valued for its medicinal as well as coloring properties. In vitro multiplication of this plant species is important for continuous supply of raw material for pharmaceutical industries as well as to conserve the germplasm of this rare and endangered species. The present work assessed the use of liquid (shake flasks and static) medium for its potential to induce shoot growth and multiplication using agar-gelled medium as a control. Shoot cultures were initiated from rhizome buds on Murashige and Skoog (MS) agar-gelled medium with 6-benzylaminopurine (BAP; 10.0 µM) and α-naphthalene acetic acid (NAA; 5.0 µM) and maintained by regular sub-culturing on Kinetin (Kn; 5.0 µM) containing medium. Best response in terms of shoot proliferation was observed in liquid shake flask cultures. MS medium supplemented with Thidiazuron (TDZ; 1.0 µM) favored 14-fold increase in shoot number followed by BAP (10.0 µM; 11 fold) and Kn (2.5 µM; 9 fold). Initial culturing in liquid shake flask with TDZ and a periodic transfer to agar-gelled medium having Kn was beneficial for sustained production of normal multiple shoots. An efficient and economic protocol was developed using liquid culture system for in vitro propagation of A. euchroma. The present protocol of in vitro shoot multiplication could be utilized for further studies related to large scale propagation as well as conservation of this plant species.