Abstract
The medicinal plant Pelargonium sidoides DC. (Geraniaceae) was traditionally used for the treatment of the common cold and
cough in South Africa. Today an aequous-ethanolic root extract from this plant is
approved for the treatment of acute bronchitis and is globally marketed also as an
immunostimulant. The increasing demand of the plant material for the industrial production
indicates the need of new effective methods for the propagation of P. sidoides. Here we report somatic embryogenesis and in vitro plantlet regeneration from somatic cells of inflorescence shoots and petioles of
P. sidoides. A one-week cultivation of explants in media containing different concentrations
of thidiazuron (1, 2.2, 3, and 4 mg/L) followed by a cultivation period without phytohormones
resulted in the induction of somatic embryos within 2–4 weeks. After 2–4 months, the
embryos generated roots and could be transferred into a greenhouse, where flower formation
took place and the development of seeds occurred with high germination rates. The
root umckalin concentration, determined by high-performance thin-layer chromatography,
was comparable to that of seed-cultivated plants (100 ± 6 vs. 113 ± 10 µg umckalin/g
dried roots). For the first time, direct somatic embryogenesis has been established
as an appropriate cultivation method for P. sidoides plants used as raw material in the pharmaceutical industry. Moreover, genetically
identical plants (chemical races) can be easily generated by this procedure.
Key words
Pelargonium sidoides
- Geraniaceae - direct somatic embryogenesis - thidiazuron - inflorescence shoots
- petioles - umckalin
