Chemical composition of the essential oil of <i>in vitro</i> propagated <i>Mentha x piperita</i> L. and <i>Mentha pulegium</i> L. under methyl jasmonate and salicylic acid foliar application in field conditions

The genus Mentha consists of several important medicinal plant species whose active ingredients are used for treating liver and prostate cancers, acute respiratory infection and allergic digestive problems, neuralgia, and migraines.

This study aimed to investigate the effects of methyl jasmonate (MeJA) and salicylic acid (SA) in the field condition on the chemical composition of the essential oil of two in vitro propagated species of Mentha genus including Mentha x piperita and Mentha pulegium.

M. piperita and M. pulegium species were propagated through the tissue culture method and the in vitro propagated plants were transferred to the farm after acclimatization. Then, the plants were treated with foliar application of MeJA and SA at four concentrations (0, 2, 4, and 6 mM) at three developmental stages. Chemical composition of the essential oils of samples were determined using a GC-MS analysis.

Both elicitors increased the level of menthol production in peppermint (M. x piperita), but in pennyroyal (M. pulegium), the level of pulegone production as the main secondary metabolite was decreased. Among different metabolites detected in the essential oil of peppermint, myrcene, octanal, γ-terpinene, ocimene, carvacrol, iso-menthol, neo-menthol, and oxygenated sesquiterpenes were the constituents with the lowest amounts under MeJA and SA treatment.

The application of MeJA and SA significantly impacted on the quality and quantity of secondary metabolites of these species. The desired performance of valuable secondary metabolites can be achieved by determining the type and dosage of elicitors.