Abstract: Disclosed is a method for preparing a composition that is capable of activating the expression of a gene involved in the synthesis of an isoprenoid, the method involving: (a) contacting a plant cell with an elicitor under conditions that allow an elicitor-induced release of a compound that activates the synthesis of an isoprenoid; and (b) recovering a composition including the compound, wherein the compound is diffusible and has a molecular weight less than or equal to 10,000 daltons. Also disclosed is a substantially pure elicitor-induced composition, the composition being capable of activating a gene involved in the synthesis of a plant isoprenoid.