Multiplication and Conservation of Threatened Medicinal Plant Arnica montana L. by in vitro Techniques

An efficient and reproducible in vitro protocol for mass production of the threatened medicinal plant Arnica montana L. (Asteraceae) was developed. The effectiveness of various combinations of plant growth regulators on A. montana clonal multiplication was assessed, using seedlings stems as initial explants. Among 12 tested nutrient media, the optimum one (MS supplemented with 1.0 mg/l BAP and 0.1 mg/l IAA) increased the organogenesis frequency up to 95% in the best origin, with mean number of shoots per explant 4.25 for 5 weeks. Sub-cultivations on this medium every 4 weeks led to increase of the propagation rate as in the fifth subculture the average number of shoots per explant reached 12.32+-0.82. Rooting of uniform in vitro shoots was 100% successful on half strength MS medium supplemented with 0.5 mg/l IBA. The ex vitro adapted plants showed 90% survival, and were further acclimatized to two mountain ex situ collections. Plants looked healthy and true-to- type and began to bloom in the second or the third year. In addition, a successful protocol for slow-growth storage of in vitro A. montana cultures was elaborated, after testing 8 media with mannitol or sorbitol. The medium 1/2 MS containing 3% sorbitol and 2% sucrose was chosen as the best one, efficiently retarding the growth of the in vitro plantlets, thus allowing 6-month maintenance without sub-cultivation. The developed in vitro protocols could be of great value for commercial propagation and sustainable conservation of this threatened medicinal plant.