In vitro propagation and improving accumulation of coumarin in Lycium barbarum, a rare plant in the flora of Egypt

Abstract

BackgroundThe conservation of natural populations of plants is very important for maintaining biological diversity. Lycium barbarum (goji berries) is classified as a very rare plant in the Egyptian flora. Goji berry is a fruit commonly known as ‘super-fruit,’ due to its beneficial constituents and medicinal properties. The aim of this study was to determine the influence of media formula added with various cytokinins on axillary bud induction of L. barbarum from shoot tip. An additional objective of this study was to investigate the effect of 2,4-D, TDZ, zeatin, IBA and NAA on growth and development of the plant through different stages. The present study also aims to improve coumarin accumulation as one of the most active constituents in the plant.ResultsSterilized shoot tips of L. barbarum were cultured without growth regulators on different media formulas: Murashige and Skoog basal medium (MS medium), Gamborg’s medium (B5 medium) and Woody plant medium (WP medium). MS medium gave the best shoot induction. The maximum multiplication rate of shoots was recorded on MS medium supplemented with 225.24 µM 6-benzyl amino purine (BAP). The best callus induction rate from in vitro derived young leaves was obtained on MS medium with 552.60 µM thidiazuron (TDZ). At 176.20 µM TDZ, the maximum shoot proliferation ability was obtained through organogenesis from the callus. MS medium with 220.25 µM TDZ produced the highest number (15 buds) and forming rate (96%) of adventitious buds through direct organogenesis. On MS medium with 304.86 µM naphthalene acetic acid (NAA), 100% rooting was obtained. Almost 95% of the in vitro-generated plantlets were successfully acclimatized. Furthermore, suspension culture containing MS medium with 552.60 µM TDZ and cinnamic acid at a concentration of 763 μM increased coumarin synthesis (1.95-fold), compared to control.ConclusionThe in vitro regeneration of plants via leaf-mediated shoot organogenesis protocol presented in this study is well suited for L. barbarum propagation and produced large quantities of identical planting materials for desert revegetation and pharmaceutical industries. A very effective indirect regeneration method via callus culture provides a potential for this ethnomedicinal plant to be improved by genetic transformation procedures, in addition to mass propagation of elite plants. The cell suspension culture medium with 763 µM cinnamic acid had the highest coumarin accumulation.