ORIGINAL PAPER Secondary somatic embryogenesis of carnation (Dianthus caryophyllus L.) Omid Karami Æ Ali Deljou Æ Gona Karimi Kordestani Received: 29 April 2006 / Accepted: 7 December 2007 / Published online: 28 December 2007 Ó Springer Science+Business Media B.V. 2007 Abstract This is the first report describing culture conditions necessary to induce secondary embryo- genesis in two carnation cultivars, Nelson and Spirit. In the first step, embryogenic calli were induced on petal explants followed by development of primary somatic embryos from the calli. In the second stage, secondary somatic embryos were obtained when precotyledonary and cotyledonary primary embryos were isolated and transferred onto a series of culture media all containing MS basal salt mixture, and supplemented with different concentrations of 2,4-D, BA, sucrose and mannitol. The highest rate of sec- ondary embryogenesis occurred on mannitol con- taining media. Secondary somatic embryos were converted into plantlets when they were transferred onto growth regulator-free half-strength MS medium and successfully acclimated in the greenhouse. Keywords Somatic embryogenesis Á Secondary somatic embryogenesis Á Carnation Abbreviations BA 6-Benzyladenine 2,4-D 2,4-Dichlorophenoxyacetic acid MS Murashige and Skoog basal medium Introduction Carnation (Dianthus caryopyllus) is an important floricultural crop with high commercial interest worldwide (Burich et al. 1996). Application of bio- technology in plant breeding programs requires efficient in vitro regeneration procedures. Somatic embryogenesis is a desirable method of plant regen- eration (Williams and Maheswaran 1986). Somatic embryogenesis is the fastest method of plant micro- propagation, and somatic embryos may be encapsu- lated in various gelling systems to form artificial seeds that can be easily stored and transported to long distances (Ghosh and Sen 1994). Due to the presence of well-developed root and shoot primordia, somatic embryos germinate easily to produce plantlets without additional step of rooting (Laux and Jurgens 1997). Secondary somatic embryogenesis involves the initiation of new somatic embryos from somatic embryos. As an experimental system it has certain advantages when compared to primary somatic embryogenesis such as a high multiplication rate, independence of an explant source and repeatability. Furthermore, embryogenicity can be maintained for O. Karami Á A. Deljou (&) Department of Biotechnology, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran e-mail: hiva@basu.ac.ir G. K. Kordestani Department of Microbiology, Kordestan Islamic Azad University, Kordestan, Iran 123 Plant Cell Tiss Organ Cult (2008) 92:273–280 DOI 10.1007/s11240-007-9332-2