**Abstract**

The production and breeding of plants with desired properties are possible by a fundamental biotechnological technique, genetic engineering. Applying and developing of genetic engineering procedures also enable preservation and improvement of plant species endangered in nature, including medicinal plant common centaury (*Centaurium erythraea* Rafn.). Numerous developmental processes in plants are controlled by cytokinins (CKs). The only so far known enzyme involved in CK catabolism is cytokinin oxidase/dehydrogenase (CKX). Genes coding for two *Arabidopsis* CKX isoforms, *AtCKX1* and *AtCKX2*, were successfully introduced into centaury root explants. Subsequently, the contents of endogenous CKs in *AtCKX*overexpressing centaury plants grown *in vitro* were investigated. Simultaneous secondary metabolite analyses showed antibacterial and antifungal activity of transgenic centaury plants and suggested their use as potential producers of anticancer compounds. Considering that centaury can inhabit saline soils in natural habitats, following investigations included evaluation of salinity tolerance *in vitro*. All obtained and summarized results indicated that transgenic *AtCKX* centaury plants could serve as a suitable model for studies of numerous physiological and developmental processes under endogenous phytohormonal control.

**Keywords:** centaury, *Centaurium erythraea* Rafn., *in vitro* propagation, *AtCKX* genes, cytokinins, salinity
