A culture system for the stable and high-efficiency proliferation of adventitious roots of Panax notoginseng and ginsenoside accumulation

Abstract

Panax notoginseng is an important medicinal plant that belongs to the Araliceae family. In this study, a stable and high-efficiency system for the proliferation of P. notoginseng adventitious roots was established via two steps, and their growth and accumulation of three ginsenosides (Rg1, Re and Rb1) was analyzed in suspension culture. Adventitious roots were firstly induced from the cotyledons of P. notoginseng seeds, in 1/2 Schenk and Hildebrandt (SH) medium with 2.0 mg L−1 indole-3-butyric acid (IBA) and 30 g L−1 sucrose. Using these adventitious roots as explants, the influence of 1/2 SH and 1/2 Murashige and Skoog (MS) medium without NH4NO3 (1/2MS-N), and IBA (0–4.0 mg L−1) and naphthalene acetic acid (NAA) (0–2.0 mg L−1) on the induction of new adventitious roots was investigated. Culture conditions of 1/2 SH with 2.0 mg L−1 IBA and 2.0 mg L−1 NAA were optimal for the formation of new adventitious roots, and led to an induction rate of 100 % and 12.62 new adventitious roots on average for each explant after 3 weeks of culture. In culture conditions of 1/2MS-N with 2.0 mg L−1 IBA and 50 g L−1 sucrose, induced adventitious roots rapidly elongated to a mean length of 14.23 mm within 3 weeks, demonstrating that a two-step process of adventitious root regeneration involving steps of initiation and elongation was most effective. Suspension cultures of adventitious roots were analyzed to evaluate the effects of culture cycle time, concentrations of sucrose and IBA and amount of inoculation on adventitious roots. After 7 weeks, the total yield of three ginsenosides (11.13 mg 100 mL-1) was highest in root cultures with 1/2 MS-N, 30 g L−1 sucrose, 4.0 mg L−1 IBA, and 3.5 g 100 mL−1 root inoculation culture. The highest total concentration of ginsenosides (18.58 mg g−1 DW) was obtained from adventitious roots cultured from 3.0 g 100 mL−1 inoculation material and the concentration of ginsenoside Re (8.05 mg g−1 DW) was 1.8-fold higher than that in 3-year-old roots cultivated in the field (4.44 mg g−1 DW). The establishment of this culture system will be beneficial for the scale-up culture of adventitious roots and ginsenoside production in P. notoginseng.