摘要：Centaurea pseudaxillaris Stef. & T. Georgiev (Asteraceae) is a Bulgarian endemic plant species with limited area comprising two populations located in the floristic regions Thracian Lowland and Toundzha Hilly Country. It is critically endangered, protected by the Biodiversity Act. To preserve the species both ex situ and in situ measures have been applied. Seeds germinated in vitro after 70 days of incubation on basal MS medium. Leaf explants isolated from the seedlings formed callus and leaf rosettes on MS medium supplemented with 1 mg/l BAP. The rosettes rooted spontaneously on the basal medium. Callus formed also on root segments and was fast growing on medium containing 0.5 mg/l BAP and 0.2 mg/l 2,4-D. Root-derived calli sub-cultured on MS free of plant growth regulators developed only roots while those transferred to media with 0.5 mg/l BAP or 1 mg/l 2iP regenerated whole plantlets. They were potted in soil substrate and ex vitro adapted using phytotron. The well-developed roots and the gradual humidity decrease were of crucial importance for the success of this step. Plants were further adapted to greenhouse and finally acclimatized to the field plot. The ex situ collection consisted of 14 plants which bloomed and gave seeds during their first year. After the wintering they grew bigger and two years later, with the help of volunteers, 9 of them were transferred to their population of origin, in order to strengthen it. Two months later the monitoring confirmed the survival of the plants which were all in very good condition
关键词：Centaurea; in vitro propagation; ex situ collection; population strengthening; biodiversity conservation
