Arabinogalactan-proteins stimulate somatic embryogenesis and plant propagation of Pelargonium sidoides.

Abstract Root extracts of the medicinal plant Pelargonium sidoides , native to South Africa, are used globally for the treatment of common cold and cough. Due to an increasing economic commercialization of P. sidoides remedies, wild collections of root material should be accompanied by effective methods for plant propagation like somatic embryogenesis. Based on this, the influence of arabinogalactan-proteins (AGPs) on somatic embryogenesis and plant propagation of P. sidoides has been investigated. High-molecular weight AGPs have been isolated from dried roots as well as from cell cultures of P. sidoides with yields between 0.1% and 0.9%, respectively. AGPs are characterized by a 1,3-linked Gal p backbone, branched at C6 to 1,6-linked Gal p side chains terminated by Ara f and to a minor extent by Glc p A, Gal p or Rha p . Treatment of explants of P. sidoides with AGPs from roots or suspension culture over 5.5 weeks resulted in effective stimulation of somatic embryo development and plant regeneration.