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  • Küçük Resim
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    Cardenolide estimation in callus-mediated regenerants of Digitalis lamarckii Ivanina (dwarf foxglove)
    (Springer, 2014) Yücesan, Buhara; Müller-Uri, Frieder; Kreis, Wolfgang; Gürel, Ekrem
    Digitalis cardenolides can regulate heart rhythms and are effective agents in cancer chemotherapy, in particular, for treating prostate and breast cancer. In this study, an optimized and efficient plant tissue culture protocol was established using callus cultures of Digitalis lamarckii Ivanina, commonly known as dwarf foxglove. Lamina explants developed callus when cultured on Linsmaier and Skoog (LS) medium containing different concentrations of 6-benzyladenine (BA; 4.4, 13.3, or 22.2 mu M) and alpha-naphthalene acetic acid (NAA; 2.7, 5.4, or 10.8 mu M). The highest incidence of callus formation (100%) was achieved on LS medium containing 13.3 mu M BA and 10.8 mu M NAA. Indirect shoot regeneration was achieved when the callus explants were cultured on LS medium supplemented with varying concentrations of BA (0.4, 1.1, or 2.2 mu M) and/or gibberellic acid (0.7 or 1.4 mu M) for 8 wk. Following the rooting of shoots on LS medium supplemented with either indole-3-acetic acid (ranging from 1.4 to 5.7 mu M) or NAA (1.3 to 5.2 mu M), lamina and petiole tissues of the 4-mo-old regenerated plants were compared for their cardenolide contents. Lamina extracts showed nearly three times higher cardenolide accumulation than petiole extracts. Of the cardenolides analyzed by reverse-phase high-performance liquid chromatography, neo-odorobioside G and glucogitoroside were abundant in lamina extracts (170.3 and 143.9 mg/kg dry weight, respectively). The regeneration protocol described in this study can be used for the in vitro production of certain cardenolides from D. lamarckii.
  • Küçük Resim
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    Somaclonal variation of cardenolide content in Heywood's foxglove, a source for the antiviral cardenolide glucoevatromonoside, regenerated from permanent shoot culture and callus
    (Springer, 2015) Kreis, Wolfgang; Haug, Birgit; Yücesan, Buhara
    Cardiac glycosides are plant natural compounds used to treat cardiac insufficiency in humans. Recent findings suggest a further medical use in oncology and virology. Since species of the genus Digitalis are the major source of these compounds, in vitro culture techniques can be useful tools for the propagation and selection of elite genotypes. Digitalis mariana ssp. heywoodii, an endemic and endangered species in Portugal, is known to have a very high content of cardiac glycosides, especially glucoevatromonoside. Here, D. mariana ssp. heywoodii plants were cloned from a seed-derived shoot explant through direct or indirect in vitro propagation. Multiple shoot formation was induced from a seed grown on agar-solidified Murashige and Skoog (MS)-based medium supplemented with 9.8 mu M indole-3-butyric acid (IBA). Shoots were used to regenerate plants directly, and some were then used as a source of root explants for callus induction and growth by transferring to MS medium supplemented with 9.3 mu M kinetin (KIN), 5.7 mu M indoleacetic acid (IAA), and 1.1 mu M 2,4-dichlorophenoxyacetic acid (2,4-D). Callus that was 3, 6, or 24 mo old efficiently developed adventitious shoots when placed on MS medium containing 13.3 mu M 6-benzylaminopurine (BAP) and 1.7 mu M IAA. Plants regenerated from either callus (R plants) or shoot cultures (S plants) were transferred to the greenhouse and propagated for 3, 4, or 10 mo. Regenerated plants were analyzed for cardenolide content and accumulation pattern. The highest cardenolide content, about 2.0 mg/100 g DW in terms of digitoxin equivalents (Dteq), was found in S10 plants (10 mo in the greenhouse), whereas plants regenerated from 24-mo-old callus (R24/10; 10 mo in the greenhouse) had the lowest cardenolide content of about 1.2 mg Dteq/100 g DW.