269 Micropropagation of Nepeta nuda ssp. nuda (Lamiaceae) – Influence of Auxins and Cytokinins Ya.Y. Nedelkova, M.A. Dimitrova, Z.P. Yordanova and V.M. Kapchina-Toteva Department of Plant Physiology Biology Faculty Sofia University ‘St. Kl. Ohridski’ Sofia Bulgaria Keywords: in vitro propagation, 6-benzylaminopurine, indole-3-butyric acid, chlorophyll content, medicinal plant Abstract The genus Nepeta (Lamiaceae) comprises more than 250 species of annuals and perennials, most of which growing wild in Central and Southern Europe, Northern Africa, Central and Southern Asia. In this study, Nepeta nuda L. ssp. nuda was collected in Lozen mountain location near Sofia and propagated successfully in vitro on MS medium. Nepeta nuda ssp. nuda has diuretic, anti-spasmodic, anti- asthmatic, antioxidant, as well as sedative properties. During the in vitro growth, the number and length of shoots, callogenesis capability, root formation, and chlorophyll a and b content were determined. The effect of a range of concentrations (0.1-1.0 mg L -1 ) of cytokinin 6-benzylaminopurine (BA), and auxin, indole-3-butyric acid (IBA), was investigated. Significant stimulation of the shoots number was observed on MS medium supplemented with 0.8 mg L -1 BA in comparison with untreated control plants. All concentrations of BA suppressed root formation, and only high concentrations induced callogenesis. Slight increase in chlorophyll a content was detected after growth on medium supplemented with 1.0 mg L -1 BA. IBA stimulated the root formation and increased the shoots’ length at high concentrations (0.7-1.0 mg L -1 ). This is the first report on in vitro propagated Nepeta nuda ssp. nuda through a direct plant regeneration approach, and the present work offers an effective alternative method for propagation and preservation of this important medicinal plant. INTRODUCTION The genus Nepeta (Lamiaceae) comprises more than 250 species of annuals and perennials, most of which growing wild in Central and Southern Europe, Northern Africa, Central and Southern Asia. Nepeta nuda L. ssp. nuda has diuretic, anti-spasmodic, anti- asthmatic, antioxidant and sedative properties. The leaves of Nepeta nuda contain variety of compounds: monoterpene, nepetalactones, iridoids and flavonoids (Gkinis et al., 2010). Recently the use of this aromatic medicinal plant has increased and gained vast popularity, especially for folk medicine and modern therapy, but its indiscriminate collection leads to diminished populations and changes in genetic diversity. Therefore, there is now an urgency to conserve wild populations of Nepeta nuda for future uses and at the same time to produce enough plant material by efficient propagation. The use of the micropropagation technique is of a high importance for the conservation, rapid multiplication, genetic improvement and pharmaceutical needs of medicinal plants. Efficient protocols for in vitro propagation have been developed to investigate the effect of different concentrations of plant growth regulators on the in vitro multiplication of Nepeta rtanjensis Diklić and Milojević, Nepeta sibirica L. and Nepeta nervosa Royle and Bentham (Mišić et al., 2005; Nestović et al., 2010). The aim of the present study is to investigate the influence of a range of concentrations (0.1-1.0 mg L -1 ) of the cytokinin 6-benzylaminopurine (BA) and of the auxin indole-3-butyric acid (IBA) on in vitro propagation of Nepeta nuda ssp. nuda. Proc. I st IS on Med., Arom. & Nutraceut. Pl. Mountainous Areas Eds.: C. Carlen et al. Acta Hort. 955, ISHS 2012