Stimulation of rosmarinic acid, essential oil and anthocyanin biosynthesis of in vitro cultures of lemon basil [ocimum americanum L.] in response to different cultural conditions

ABSTRACT

Shoot-tip explants of germinated plantlets of O. americanum were inoculated aseptically on MS-medium hormone-free and MS supplemented with different concentrations of NAA and/or BA. Stimulation of rosmarinic acid synthesis in leaf, stem and root derived calli in response to increasing levels of NaCl as salt stress in the culture media was examined. The proliferated shoots, roots and the stressed callus tissues were subjected to rosmarinic acid analysis by HPLC. However, leaf-derived callus was investigated under light and dark conditions and increasing levels of 2,4-D in the culture media for essential oil content, composition and anthocyanin accumulation. The obtained results indicated that both in vitro produced shoots and roots of all treatments accumulated high rosmarinic acid content than intact plant. Increasing NaCl concentration in the culture media up to 0.3% caused a reduction in rosmarinic acid content of leaf and stem derived callus tissues. Moreover, callus tissues incubated under dark condition showed higher values of volatile oil [%] as compared with callus tissues grown under illumination. The sesquiterpenes content of the essential oil were the best under light condition, while monoterpene hydrocarbons and oxygenated monoterpene were higher under dark condition. The higher values of anthocyanins was recorded with callus tissues grown under light condition. It is observed that anthocyanin synthesis is influenced by levels of 2,4-D added to the culture media