In vitro propagation of Lychnophora pinaster (Asteraceae): A threatened endemic medicinal plant

Abstract

Lychnophora pinaster, known as arnica, is a medicinal plant of the Cerrado ecosystem in Brazil. It is widely used in the form of alcoholic extract for its antiinflammatory and anesthetic and healing effects on sprains, bruises, and inflammation. Owing to the great difficulty of propagation, it is listed by the Institute Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis in the category of plants vulnerable to extinction. Micropropagation offers a solution to this problem by allowing the preservation and expansion of germplasm. The objective of this research was to establish a protocol for in vitro propagation of arnica. The best medium for germination of arnica embryos and plantlet growth was a quarter strength semisolid Murashige and Skoog medium (MS/4) containing 0.75% (w/v) sucrose. For shoot induction, the best results were obtained on MS/4 with 2.76 μM of benzylaminopurine. Maximum shoot elongation before rooting occurred in the presence of 8.67 μM of gibberellic acid for 19 d. Microshoots were successfully rooted in the presence of 10.7 μM of naphthalene acetic acid for 15 d. After rooted plantlets were acclimatized in a greenhouse for 20 d, the survival rate was 100% when planted in a soil from the area of occurrence of the species, whereas 0% survived when planted in Plantmax.