Title : Elicitation alters the concentration of carnosic acid and carnosol and increases essential oil production in rosemary plants
Abstract:
Research on elicitation in rosemary has mainly focused on increasing the yield of essential oil (EO). However, there is little information addressing the impact of elicitation on the levels of carnosic acid (CA) and its derivative, carnosol (COL) in rosemary leaves. In this study, we investigated the effects of salicylic acid (SA) and seaweed extract (SWE) on growth, biosynthesis of secondary compounds and antioxidant activity in rosemary plants grown in a greenhouse. Two experiments were performed, in which SA and SWE were sprayed at four regular intervals and leaves were collected at different times after the last application of the elicitors. Plants treated with SA and SWE showed significant increases in EO concentration, without altering their morphology. The EO of plants treated with SWE presented higher contents of α-pinene, β-myrcene and 1,8-cineole. The leaf extract of the elicited plants showed higher antioxidant activity by analysis of β-carotene. The elicitation of plants with SA and SWE promoted inhibition of CA biosynthesis and stimulation of its oxidation into COL. However, this response was observed at 24 and 48 h after spraying the plants. Plants at harvest point showed no differences regarding CA, yet a higher concentration of COL in the leaf extract was observed. Additionally, there was a decrease in rosmarinic acid (RA) in plants treated with SWE, both in samples taken 24 and 48 h after spraying and in samples taken from plants at harvest point. In the second experiment we also investigated the expression of the key genes related to CA biosynthesis. Both elicitors provoke changes in the transcriptional profile of the CPS1 and KSL2 genes in leaves collected 24 and 48 h after spraying. These results indicate the potential of elicitation with SA and SWE as a strategy for obtaining rosemary plants with higher EO and COL foliar concentrations.
