Biosynthesis of essential oil compounds in Ocimum tenuiflorum is induced by abiotic stresses

The herb holy basil (Ocimum tenuiflorum) is rich in essential oil, which is important in pharmaceutical, nutraceutical, cosmetic, and food industries. O. tenuiflorum grows well in tropical, subtropical, and warm temperate regions. To induce essential oil biosynthesis, holy basil plants were exposed to cold or drought stress for 5 days. Gas chromatography-mass spectrometry (GC-MS) analyses revealed that essential oil components including eugenol, methyl eugenol, and beta-caryophyllene were significantly accumulated in 30-day-old juvenile and 130-day-old pre-flowering plants. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed that expressional levels of OtEOMT transcript increased by almost 5-fold following the juvenile stage, and by 16.78- to 66.02-fold following the pre-flowering stage among cold-treated plants. These results suggest a biotechnological strategy to increase essential oil content by treating holy basil plants with cold or drought stress at the juvenile and pre-flowering stages.