Somatic embryogenesis of Pelargonium sidoides DC.

Abstract

Pelargonium sidoides is a high value medicinal plant endemic to South Africa and the Lesotho Highlands. Establishing an efficient regeneration system through somatic embryogenesis is necessary for its conservation. An efficient reproducible protocol for in vitro plant regeneration via somatic embryogenesis of Pelargonium sidoides, an important medicinal plant, is reported for the first time. Embryogenic callus was obtained on Murashige and Skoog (MS) basal medium supplemented with 2.0 mg L−1 picloram, 0.5 mg L−1 thidiazuron and 20 mg L−1 glutamine. Different developmental stages of somatic embryos (SEs: globular embryos, heart shaped embryos, torpedo shaped embryos and cotyledon embryo with radicle) were directly obtained and further matured from embryogenic callus by subsequent subculture on the same medium. The highest frequency of somatic embryos (25.89 ± 1.50) was recovered after 6 weeks. Scanning electron microscopic (SEM) analysis revealed the presence of embryogenic cell clusters that formed cotyledonary embryos. Mature somatic embryos germinated and developed into plantlets after 4 weeks on half-strength MS medium. High plant regeneration frequency (94.4 %) was achieved on half-strength MS medium supplemented with 1.0 mg L−1 gibberellic acid. Rooted plantlets were successfully acclimatized in the greenhouse with a survival rate of 90 %. The protocol developed would be helpful in reducing stress on natural habitats, provide a system for germplasm conservation, regeneration of large numbers of high value clonal plants for commercial production, the isolation of bioactive compounds and genetic transformational studies.