Evaluation of Morphological and Phytochemical Diversity of different Populations of Phlomis olivieri Benth. in Hamedan Province

 Medicinal plants have played an essential role in the development of human culture. Medicinal plants are resources of new drugs and many of the modern medicines are produced indirectly from plants. Although the production of secondary metabolites is controlled by genes, their production is considerably influenced by environmental conditions, so environmental factors cause changes in the growth of medicinal plants as well as the amount of active substances. Essential oil quantity and quality are affected by the different environmental conditions. Physiological, morphological and genetic variations were seen in populations of species that occurred in different habitats. These variations were created in response to contrasting environmental conditions. In many plant species, studies on the pattern of variation in populations have shown the localized populations are adapted to the particular environmental conditions of their habitat. The genus Phlomis L. (Lamiaceae) includes about 113 perennial herbs or shrubs distributed in Asia, Europe, and Africa. Some of the Phlomis species have been reported for their traditional uses as analgesic, diuretic, tonic, anti-diarrheic agents and to treat various conditions such as gastric ulcer, inflammation, diabetes, hemorrhoids and wounds. In Flora of Iran, this genus is represented by 20 species, including Phlomis olivieri Benth.
 This study was conducted to evaluate the morphological and phytochemical diversity of eleven populations of P. olivieri Benth. from different districts of Hamedan province in 2021. Traits such as plant height, stem diameter, leaf length and width, fresh and dry weight of the flowering branch, inflorescence length, fresh and dry weight of the plant, number of inflorescence cycles, essential oil percentage were measured. In order to investigate the physical and chemical properties of soil, soil samples were collected from a depth of 30 cm. Then they were transferred to the soil laboratory. Plants samples were collected in the flowering stage and were dried at 25-30°C. They were stored in envelopes at 22±3°C away from the sun. For extracting the essential oil of the samples, 100 gr of the plant was milled and then distilled with water. Hydrodistillation lasted for 4 hours. The main components of essential oil were identified and determined by gas chromatography in the Institute of Medicinal Plants in Karaj. Gas chromatography was carried out on Agilent 6890 with capillary column 30m*0.25 mm, 0.25 mm film thickness. The grouping of populations based on morphological and phytochemical traits was done by cluster analysis in SPSS using the Ward method. Also, the traits correlation (quantitative) was done using the Pearson method.
 According to the results, the highest fresh and dry weight of flowering branch (6.96 g and 3.48 g) and also the highest fresh and dry weight of the plant (11.77 g and 5.86 g) belonged to the Koohani population. The tallest inflorescence (24.2 cm) belonged to the Jowzan population and the shortest inflorescence belonged to the Gammasiab population (8.9 cm). The highest stem diameter (4.45 mm) was observed in the Garin population. The maximum plant height (49.4 cm) was related to the Rahdarkhaneh population, which was not significantly different from the Garin population, and the minimum was related to the population of Garmak (31 cm), which was not significantly different from the population of Gammasiab (33.50 cm). Also, 31 compounds were identified in this plant essential oil that caryophyllene, germacrene D, and (E)-b-Farnesene had the highest percentage of essential oil constituents. In this study, the highest amount of essential oil (0.04%) was related to the Koohani population which had the lowest altitude among other populations. Therefore, it seems that environmental factors, as well as genetic factors, have been effective in creating diversity in morphological and phytochemical characteristics of this plant.
 The results obtained from this study showed that P. olivieri Benth. populations gathered from different regions of Hamedan province, had a high diversity in terms of essential oil content. The results showed that in addition to genetic factors, environmental and climatic factors also affect phytochemical traits. In this study, the highest amount of essential oil was produced in the Koohani population (located in Nahavand city) with the lowest altitude among other populations. According to the research on the essential oil components of P. olivieri in different regions of Iran, the components of its essential oil and their percentages are completely different; so, some of the components that are seen in one region, are not observed in another region, and this issue emphasizes on the effect of climatic conditions. This difference is quite evident even in the studied populations in a province.