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

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

Effect of growth regulators on growth, essential oils content and anthocyanin accumulation in basil, [ocimum americanum L.] shoot cultures

Shoot tips of aseptically growing seedlings of O. americanum were cultured on plant growth regulators-free culture medium [control] or on media containing 0.25 mg/l IAA and different concentrations [1,2 and 3 mg/l] of BA. The morphogenic response of the cultured shoot tips in the tested media were evaluated. Composition of the volatile oil from both shoot cultures and intact plant leaves of 0. americanum were analyzed by Gas Chromatography-Mass Spectrometry [GC-MS]. The volatile oil content and anthocyanin accumulation were determined. Clear differences between tested treatments of the produced plantlets were observed in terms of growth data after 6 weeks of culture. According to the respective growth indexes, the plantlets grown in free-growth regulators medium was the best in growth. However, Qualitative and quantitative changes in essential oil content and composition of plantlet oil were also observed in response to the effect of BA level in the culture medium. These results also indicated that anthocyanin synthesis was most active in basil shoot cultures grown in medium with BA not more than 1 mg/l with 0.25 mg/l IAA