Abstract

Plectranthus edulis (Vatke) Agnew is a tuber-bearing food crop in Ethiopia. However, its productivity is hampered by shortage of pathogen-free planting materials. Therefore, the objective of this study was to develop micropropagation protocol for this plant using meristem to produce clean planting materials. Mersitems were collected from apical and axillary shoots from Holeta and Welayta areas and cultured on MS medium containing gibberellic acid (GA₃) (1.0 mg l^-1), α-naphthalene acetic acid (NAA) (0.1 mg l^-1) in combination with 6-benzylaminopurine (BAP) (0.1, 0.5, 1.0, 2.0 and 5.0 mg l^-1). Shoots were multiplied on MS medium containing 0.1, 0.5, or 1.0 mg l^-1 of BAP or 0.5, 1.0, 2.0 or 3.0 mg l^-1 of Kinetin alone or their combination with 0.05 or 0.1 mg l^-1 NAA. In vitro and ex vitro rooting was performed using different types of auxins followed by acclimatization. The highest percentage of shoots initiated from collected mersitem at Holeta (73%) was obtained on MS medium containing 1.0 mg l^-1 BAP, 1.0 mg l^-1 GA₃ and 0.1 mg l^-1 NAA. The highest shoot number explants^-1 (7.2) was obtained on MS medium containing 1.0 mg l^-1 Kinetin and 0.1 mg l^-1 NAA, whereas the highest root number shoot^-1 (6.2) was obtained from ex vitro. All plants derived from Holeta and 96.7% of those from the Welayta survived after acclimatization. These results provided rapid and reproducible conditions for propagation of relatively pathogen-free planting material of this plant.

Key words: In vitro propagation, meristem culture, micropropagation, Plectranthus edulis (Vatke) Agnew, shoots multiplication. 

Abbreviation

GA_3, Gibberellic acid; NAA, α-naphthalene acetic acid; BAP, 6-benzylaminopurine; PGR, plant growth regulator; IAA, indole-3-acetic acid; IBA, indole-3-butyric acid.