IN VITRO MICROPROPAGATION OF Helichrysum arenarium (Asteraceae) AS A TOOL FOR INTRODUCING THE SPECIES IN AGRICULTURE

Helichrysum arenarium, known as sandy everlasting, is a perennial plant species, used in traditional medicine. In Bulgaria, it is protected by the Biodi-versity Act and under a special regime of use based on the Medicinal Plants Act. Seeds from five Bulgarian populations were in vitro germinated and seedlings were sub-cultured on five media supplemented with different plant growth reg-ulators (PGRs) and control MS medium free of PGR. The type of cytokinin turned out to be of crucial importance, as the presence of kinetin stimulated formation of rhizomes and direct organogenesis, BAP caused callogenesis, in-direct organogenesis and hyperhydricity, and Meta-top olin - necrosis. Best results were obtained on medium with reduced macrosalt and sucrose concen-trations as rhizomes gave rise to numerous well-developed and spontaneously rooted plantlets, up to 55 originating from a single seed. Plants were potted in soil mixture, adapted to phytotron conditions, and transferred to the green-house for acclimation, then planted on the ex situ collection. All plants flowered during the first summer outdoor. Nuclear DNA amount was measured by flow cytometry to check possible abnormalities of the in vitro multiplied plants. The estimated DNA amount varied in the range 1C = 0.85-0.89 pg. No deviations in the ploidy level were detected. No difference between the studied populations was found. In vitro micropropagation was shown to be an appropriate method for rapid plant multiplication of H. arenarium thus offering the opportunity for its introduction into agriculture.