ASSESSMENT OF THE EFFECT OF PLANT GROWTH REGULATORS ON IN VITRO MICROPROPAGATION AND METABOLIC PROFILES OF MELISSA OFFICINALIS L. (LEMON BALM)

In this study the effectiveness of plant growth regulators on micropropagation, total phenol content and metabolic profiles of Melissa officinalis L., important medicinal herb was assessed. The stem segments derived from one-month old in vitro germinated seedlings were used for initial explants. Of the eight different nutrient media tested the most favorable for micropropagation were found to be MP2 (MS medium enriched with 1mg/L BAP and 0.1 mg/L IBA) and MP3 (MS supplemented with 1.5 mg/L BAP and 0.5 mg/L NAA), which yielded 3.25- 4.0 shoots per explant within 4 weeks of culture. In vitro rooting (100%) was achieved on half strength MS medium contained 2% sucrose. Rooted plantlets were adapted successfully (98%) in a mixture of soil, peat, perlite, and sand in ratio 2:1:1:1 (v/v/v/v). Twenty metabolites were identified by GC/MS analysis of shoots grown on the MS media including different types of growth regulators. Analysis revealed the presence of phenolic, organic and fatty acids, sterols, triterpenes, fatty alcohols, saccharides and polyols. The studied samples have the same metabolic profile with quantitative differences in the individual metabolites. The maximum content of total phenols (13.92 mg/g extract) was obtained in shoots grown on MP2 medium and the lowest was recorded in the microplants cultured on MP1 control medium (8.45 mg/g extract). The obtained results indicated that it is possible to achieve the accumulation of desired metabolites by selection of plant growth regulators added in nutrient media.