Effects of inoculation by arbuscular mycorrhizal fungi on the composition of the essential oil, plant growth, and lipoxygenase activity of Piper aduncum L.

The aim of this study was to evaluate the changes in the production of secondary metabolites Piper aduncum seedlings were inoculated by spores of the arbuscular mycorrhizal fungi (AMF) Rhizophagus clarus and Claroideoglomus etunicatum. P. aduncum seedlings were inoculated by spores of R. clarus and C. etunicatum and then, development parameters, root colonization, lipoxygenase (LOX) activity, and essential oil (OE) chemical composition were monitored at 30, 60 and 90 days’ post-inoculation (dpi). The inoculation had influenced the plant height and root length at 30 and 90 dpi and microscopic analysis of roots showed the presence of hyphae, arbuscules and vesicles in the inoculated plants. Phenylpropanoids and sesquiterpene hydrocarbons were the main compounds in the EO. In the leaves, the concentration of phenylpropanoids showed a decrease, mainly at 60 dpi, with increased sesquiterpene hydrocarbon production. The main compounds were dillapiole, myristicin, and germacrene D; the dillapiole concentration decreased in all treatments. LOX activity had an increase in the leaves and roots at 90 dpi. These results suggest that alterations in the secondary metabolites of P. aduncum can be induced by its mechanisms of resistance during AMF interaction.