LAUSR

This study was conducted to investigate in vitro regeneration potential of Centaurea amaena, a critically endangered and an endemic plant in Turkey. For this purpose, cotyledon, leaf and cotyledon node explants were cultured in Murashige and Skoog (MS) media supplemented with different concentrations of 6-benzylaminopurine (BAP; 1-4 mg L), thidiazuron (TDZ; 0.3-1.2 mg L) or metaTopolin (mT; 0.5-4 mg L) with or without 0.5 mg L α-naphthalene acetic acid (NAA). In axillary shoot regeneration experiments from cotyledon node explants, the greatest number of shoots per explant (9.975) was obtained from 4 mg L mT-containing MS media, which yielded a shoot regeneration frequency of 70.83%. In indirect organogenesis experiments, the greatest number of shoots per explant in cotyledons (4.152 shoots/explant with the shoot regeneration frequency of 55.00%) was obtained from 1 mg L -1 mTcontaining media and the greatest number of shoots per explant in leaves (4.132 shoots/explant with the shoot regeneration frequency of 50.00%) was obtained from 4 mg L mT-containing media. Only callus induction was observed in TDZ-containing media or combinations of TDZ concentrations with NAA. About 50.00% root formation was achieved from half-strength MS medium containing 2.0 mg L indole3-butyric acid.