ORIGINAL PAPER Regeneration and cardiotonic glycoside production in Digitalis davisiana Heywood (Alanya Foxglove) Ekrem Gurel • Buhara Yucesan • Esra Aglic • Songul Gurel • Sandeep K. Verma • Munevver Sokmen • Atalay Sokmen Received: 6 May 2010 / Accepted: 12 August 2010 / Published online: 1 September 2010 Ó Springer Science+Business Media B.V. 2010 Abstract A high-frequency in vitro regeneration of Digitalis davisiana Heywood (Alanya foxglove) and car- diotonic glycoside production from both in vitro produced materials (regenerated plantlets or germinated seedlings) and leaves of natural populations were obtained. Cardiac glycosides regulate heart rhythm and are effective in cancer chemotherapy, in particular for prostate and breast cancer treatments. Testing six different types of culture media revealed that Linsmaier and Skoog (LS) was the most effective for shoot production. Shoot regeneration effi- ciency was higher when flamingo-bill or hypocotyl explants were cultured on LS medium containing 0.5 mg/l thidiazuron (TDZ) and 0.25 mg/l indoleacetic acid (IAA). Rooting of all shoots that regenerated was readily achieved, even in the absence of plant growth regulators (PGRs). Production of cardenolides (lanatoside C and digoxin) in the materials grown in vitro seemed to correlate with several parameters, such as nutritional and hormonal compositions of the culture medium as well as the duration of culture on the initial regeneration and/or final growth medium. Higher amounts of digoxin accumulation were obtained when shoots were regenerated on LS or Gam- borg’s B5 medium containing 0.5 mg/l TDZ and 0.25 mg/l IAA, producing 12.59 and 11.93 mg/kg dry weight (dw) digoxin, respectively. For natural populations, seasonal variations seemed to affect the production of digoxin in the leaves. The highest amount of digoxin (246.58 mg/kg dw) was in leaf samples collected in July, which coincides with the flowering stage of the plant in the region of collection. Keywords Digitalis davisiana  Alanya foxglove  Plant regeneration  Lanatoside C  Digoxin  In vitro plants  Natural populations Introduction Members of the genus Digitalis are medicinally and eco- nomically important plants, as they contain cardiac glyco- sides that increase contractions of the heart and regulate heart rhythm (Baytop 1999). In addition to the cardiotonic effects of lanatoside C, digoxin and digitoxin, preliminary studies revealed that digoxin and digitoxin are also effective agents in cancer chemotherapy, in particular for prostate and breast cancer treatments (Yeh et al. 2001; Lopez-Lazaro 2007; Newman et al. 2008). Because cardenolides have been of commercial interest over the last two decades, studies have focused on in vitro culture of several Digitalis species (Hagimori et al. 1982; Kuberski et al. 1984; Perez-Bermudez et al. 1985; Kubalakova et al. 1987; Beale et al. 1988; Brisa and Segura 1989; Kreis et al. 1990; Vela et al. 1991; Gavidia et al. 1993; Pradel et al. 1997; Sales et al. 2003; Perez-Alonso et al. 2009). Digitalis davisiana Heywood (Alanya foxglove), which belongs to the Plantaginaceae family, is an endemic species E. Gurel (&)  B. Yucesan  E. Aglic  S. K. Verma Department of Biology, Abant Izzet Baysal University, 14280 Bolu, Turkey e-mail: gurel_e@ibu.edu.tr S. Gurel Department of Plant Breeding, Sugar Institute, 06790 Ankara, Turkey M. Sokmen Department of Chemistry, Karadeniz Technical University, 61080 Trabzon, Turkey A. Sokmen Department of Biology, Karadeniz Technical University, 61080 Trabzon, Turkey 123 Plant Cell Tiss Organ Cult (2011) 104:217–225 DOI 10.1007/s11240-010-9824-3