Terpenoid Essential Oil Metabolism in Basil (Ocimum basilicum L.) Following Elicitation.)

The induction of terpenoid biosynthesis has been observed in many plant species. The accumulation of the ter-penoid essential oils in basil (Ocimum basilicum L.) following elicitors treatment was investigated in this work. Plants that exhibited the same stage of development after approximately two weeks in a hydroponic system were selected for treatment with the elicitors chitosan, methyl jasmonate and methyl salicylate. Following elicitation, plants were manually collected and the remaining non-harvested plants were collected after 72 h, 96 h, 144 h and 192 h. The time-course of terpenoid accumulation showed signifcant higher levels of the sesquiterpene β-caryophyllene and the monoterpenes linalool, 1,8-cineole and limonene. Treatment of plants with chitosan resulted in no induction of the monoterpene limonene and the response on concentration of the other terpenoids was more varied compared to methyl salicylate and methyl jasmonate. Elicitation with methyl jasmonate required the longest time period (192 h after initiation of treatment) to show a signifcant increase in terpenoid production and also resulted in the most uniform response in biosynthesis comparing to the other elicitors. Induction by methyl salicylate occurred in a shorter time frame compared with the other elicitors. The total percentage increase of terpenes at the end of the experiment with respect to the beginning showed a lower effect on methyl salicylate and chitosan treated plants. Methyl jasmonate was the only elicitor that resulted in total percentage increase of β-caryophyllene, 1,8-cinelole, linalool and limonene.