Trichome Structures and Characterization of Essential Oil Constituents in Iranian populations of Salvia limbata C.A. Meyer

Salvia limbata C.A. Meyer (Lamiaceae) is an aromatic medicinal herb growing wild in various parts of Iran. In the current study, variations in the trichomes morphology and density, and composition of the hydro-distilled obtained essential oils of eight wild S. limbata populations were assessed. Essential oil yield showed a high degree of variability among the populations. The major constituents of essential oil were similar in all of the examined populations, except for Damavand population. In this population, two oil components were detected to be higher than 78% of total oil constituents. According to the principal components and cluster analysis, four groups identified with regard to the essential oil compositions: populations containing isospathulenol and aromadendrene (group I), populations with the presence of linalool, spathulenol and δ-elemene (group II), populations containing the high percentage of 1, 8-cineol (group III) and populations were characterized by the high percentage of α-pinene (group IV). The leaves of plants from all populations were covered by villous indumentum, except for Damavand population, which showed tomentose indumentum. Two types of trichomes such as glandular (peltate, capitate and digitate) and non-glandular (unbranched oneto nine-celled) were registered. The analysis of variance revealed significant variations for some of them. Totally, group I had the unique indumentum and essential oil composition, therefore, has been defined as a new chemotype for this species. Such indumentum and chemical differences clearly revealed the environmental impact on the micromorphological and essential oil compositions among the populations. The presence of high isospathulenol content in plants of Damavand population suggests their potential as strong antibiotics. However, the findings also indicate that a proper exploitation of the medicinal properties in this plant highly related to the location of sampling site, which positively contributes to its medicinal value.