Cytokinin-Mediated Modulation of Essential Oil Composition in Lemongrass (Cymbopogon citratus Greenhouse Plants Derived In Vitro): Hydrodistillation-Based Characterization and Biomass Scaling Model

Lemongrass (Cymbopogon citratus) essential oil is mainly composed of the acyclic monoterpene aldehydes geranial (α-citral) and neral (β-citral), collectively known as citral, which exhibit documented cytotoxic activity against cancer cell lines, as well as geraniol and limonene, among other monoterpenoids. In a previous study we reported that the constituents of the essential oil (EO) composition of lemongrass in vitro plants were modulated by different types of cytokinins (CKs) exogenously added to the culture medium. However, in that work, EO components were detected as volatile headspace compounds by SPME-GC/MS rather than as bulk oil extracts directly injected to GC/MS. Therefore, in this study, EOs were extracted by hydrodistillation from plants micropropagated with different CKs (BAP or 2iP) under different osmotic conditions (MS 3/3 and MS 5/5) and subsequently established in a greenhouse. Analysis of EO in C. citratus plants showed that plants grown on MS-3/3 BAP had more α-citral, and plants grown on MS-5/5 2iP had more limonene. This study demonstrates the impact of various CKs on EO production in lemongrass. The findings showed that 5/5 2iP produced the highest limonene yield, indicating a potential yield of 100 mL from 8719 plants. Similarly, 101 plants under the 5/5 Ctrl treatment are required for 100 mL of citral, and 34 plants under the 5/5 Ctrl treatment are required for 100 mL of geranyl acetate. The 5/5 2iP requires 816 plants to produce 100 mL of geraniol, and it takes 11,340 plants to produce 100 mL of β-caryophyllene from the 3/3 2iP treatment.