Abstract

A protocol was developed for Plectranthus barbatus for high frequency shoot organogenesis from leaf derived callus of aseptically grown plantlets derived from mature plant explants of high yielding clones (yield of forskolin 1.5 to 1.9%) on Gamborg medium (B₅) medium supplemented with 2 mg/l 2,4- dichloro phenoxy acetic acid (2,4-D). Shoots were regenerated from the callus on MS medium supplemented with 6-benzyl amino purine (BAP) (2 mg/l) + naphthalene acetic acid (NAA) (1 mg/l). The highest rate of shoot multiplication was achieved at the 6^thsubculture and more than 2000 shoots were produced from callus clump. Roots were induced from shoots of in vitro grown plantlets on basal half strength MS medium and high rooting frequencies were obtained. Regenerated plants were easily acclimatized in greenhouse conditions and later transferred to soil with 100% survival. The procedure here allows the micropropagation of P. barbatus in five months of culture and proliferated cell masses which could be used for studies of organic compounds of pharmaceutical interest.

Key words: Callus culture, medicinal plant, root induction, shoot organogenesis.

Abbreviation

AC, Activated charcoal; BAP, 6-benzyl amino purine; B₅, Gamborg medium; IAA, indole acetic acid; IBA, indole  butyric acid; Kn, Kinetin; MS, Murashige and Skoog medium; NAA,  naphthalene acetic acid; PVP, poly vinyl pyrrolidine; 2,4-D,2,4- dichloro phenoxy acetic acid; 2,4,5-T, 2,4,5-trichloro phenoxy acetic acid; 2,4,5, TP, 2,4,5-trichloro phenoxy propionic acid.