Exogenous application of methyl jasmonate affects the emissions of volatile compounds in lavender (Lavandula angustifolia)

The plant hormone, methyl jasmonate (MeJA), is an orthodox elicitor of secondary metabolites, including terpenoids. Lavandula angustifolia is an important aromatic plant generating, yet few studies have been performed to evaluate the function of MeJA on the biosynthesis of terpenoids in lavender. Five treatments (with concentrations of 0, 0.4, 4, 8, and 16 mM) were set, and the physiological indicators of each group were determined after 0, 6, 12, 24, 48, and 72 h. The results illustrate that (1) MeJA could affect the diurnal rhythm of the emission of volatiles and MeJA acted in a dose-dependent and time-dependent manner; (2) 8 mM MeJA treatment increased the total content of the volatiles, and the contents of monoterpenoids and sesquiterpenoids were up-regulated 0.46- and 0.74- fold than the control at 24 h and 12 h, respectively; (3) after MeJA treatment, all the genes expression analyzed changed to varying degrees, of which 3-carene synthase (La3CARS) gene changed most significantly (7.66- to 38.02- fold than the control); (4) MeJA application was associated with a rise in glandular trichome density. The positive effects of MeJA indicate that the exogenous application of MeJA could be a beneficial mean for studies on the biosynthesis of terpenoids in lavender.