Micropropagation of Monarda fistulosa L. Plants by Axillary Bud Proliferation

Abstract

The procedure of micropropagation for efficient and stable conservation of Monarda fistulosa L., a medicinally important plant belonging to the Lamiaceae family, was developed. Our research consisted of the introduction in vitro culture of the precious genotype from a biochemical point of view, identified as a result of multiple analyzes carried out by the researchers of the Scientific Medicine Research Center of the ʼNicolae Testemitanuʼ State University of Medicine and Pharmacy. This genotype is characterized by an increased content of secondary metabolites (thymol and carvacrol). Axillary bud proliferation was initiated from nodal explants grown on ½ Murashige-Skoog (MS) nutrient medium supplemented with various cytokinins, such as 6-benzylaminopurine (BA), 6-(α, α-dimethylallylamino)-purine (2iP) and cytokinin-like growth regulators – thidiazuron (TDZ) with a concentration of 0.5 mg.L^-1. After 6 weeks of culture on a nutrient medium, containing 0.5 mg.L^-1 BA was determined the maximum number of axillary shoots per explant (2.75 ±0.86) and the highest number of internodes per shoot (11.66 ±1.30). At the same time, the rhizogenesis was induced on that medium that allows in vitro micropropagation by a single stage. The advantages of the elaborated procedure are reducing reagents and energy expenses for in vitro cultivation by two times and increasing the coefficient of multiplication from 13 to 32.