Investigation of Some Functional and Ecological Characteristics of The Endemic Species Nepeta Eremokosmos Rech.F. and Its Conservation Status in Iran

IntroductionNumerous studies on the chemical composition of Nepeta species essential oils in Iran show that changes in chemical composition are influenced by various factors including geographical location, weather conditions, plant growth stages, and analysis techniques. It is crucial to understand the variables that influence the effective substances of these medicinal plants. Nepetalactone is the first chemotype for the essential oils of plants in this genus. Nepetalactone can be divided into different isomers. For example, 4aα,7α,7aα-Nepetalactone found in Nepeta cephalotes Boiss., Nepeta crassifolia Boiss. & Buhse, Nepeta mirzayanii Rech.f. & Esfand. and Nepeta racemosa Lam.; 4aα,7α,7aβ-Nepetalactone in Nepeta cataria L., Nepeta meyeri Benth. and Nepeta pogonosperma Jamzad & Assadi; and 4aβ,7α,7aβ-Nepetalactone in Nepeta bornmuelleri Hausskn. & Bornm., Nepeta eremophila Hausskn. & Bornm. and Nepeta persica Boiss. are highly useful as biochemical markers for Nepeta essential oil in chemotaxonomic studies. The 1,8-Cineole chemotype or with Linalool makes up the second category. The first chemical is the most prevalent in a number of Nepeta species, including Nepeta binaloudensis Jamzad, Nepeta crispa Willd., Nepeta denudata Benth., Nepeta ispahanica Boiss. and Nepeta menthoides Boiss. & Buhse. The essential oils of Nepeta species in Iran contain 33 effective substances in a significant amount. These oils are comprised of monoterpenes and hydrocarbon sesquiterpenes. To date, research on the phytochemical variety of Nepeta species and how ecological conditions affect their morphological characteristics and secondary metabolites has only looked at Nepeta asterotricha Rech.f., Nepeta binaloudensis, Nepeta eremokosmos Rech.f. and Nepeta pogonosperma. In these studies, it has been frequently mentioned that altitude affects the quantity and quality of beneficial substances found in the species of this genus. There has been no exploration of other factors related to the species' habitat. The purpose of this research project was to conduct a thorough investigation of the effect of environmental parameters on the essential oil composition of medicinal species Nepeta eremokosmos. Material and MethodsIn Semnan province, three different habitats for Nepeta eremokosmos, each with distinct environmental conditions, were selected. A systematic random method was used to establish a series of plots in each habitat. Vegetative traits, such as plant height, canopy diameter, canopy cover,  biomass, and leaf area, were meticulously measured in every plot. To prepare a herbarium sample, the flowering aerial parts of Nepeta eremokosmos were collected in June 2022 from three specific regions: Momenabad, Hajjaj, and Javin. Three replicates of the flowering branches of Nepeta eremokosmos were taken from each population. The samples were dried in both the open air and shade after being transferred to the laboratory. The Clevenger apparatus was used to extract the essential oils through hydrodistillation after grinding the dried samples. GC-FID and GC/MS were used to identify essential oil compounds. In each habitat, five soil samples were also collected, and important physicochemical parameters such as pH, EC, OM, N, P, K, lime, gypsum, and soil texture were measured. Afterwards, the data were examined by conducting one-way variance analysis and comparing mean values using SPSS software. Correlation analysis was used to determine the most significant environmental factors that influenced vegetative traits and essential oil compounds. Moreover, principal component analysis was carried out using Minitab software. The conservation status of Nepeta eremokosmos was determined using the IUCN method and based on the criteria of EOO and AOO using GeoCAT software, as well as data related to population size and habitat quality. Results and DiscussionNepeta eremokosmos' vegetative traits varied significantly between the three regions in terms of plant height and leaf area, with a 0.1% difference, the canopy diameter and cover are at 1%, while the biomass is at 5%. The comparison of mean vegetative traits revealed that the highest values of height, canopy diameter, canopy cover, leaf area, and biomass, with 20.8 cm, 34.1cm, 2.3%, 4.1cm2, and 30.1g, respectively related to Momenabad habitat. The variance analysis of essential oil components in three populations of Nepeta eremokosmos revealed that their effective substances were significantly different at levels of 0.1, 1 and 5%. The Momenabad habitat contained 1,8-Cineole, 4a, 7a-Nepetalactone, and p-Cymene, with a respective concentration of 50.8, 7.2, and 6.5%. Hajjaj had the highest concentration of 1,8-Cineole, Myrtenal, and p-Cymene, while Javin had 20, 8.7, and 8.1%. According to the variance analysis of soil chemical parameters of Nepeta eremokosmos, the three habitats had a significant difference of 0.1%. By comparing the mean parameters, it was demonstrated that the soil in Momenabad habitat is more acidic and lighter. The concentrations of OM, N, SP, P, and gypsum were elevated with 0.24%, 4.4%, 65.1%, 5.4 mg/l, and 73.9%, in comparison to other habitats. Javin habitat had an EC, K, and lime level that was 1.5 ds/m higher than those in the other two habitats by 117.4 mg/l and 31.6%. Among the environmental factors, altitude, annual precipitation, annual temperature, maximum temperature of the hottest month, N, P, K, OM, gypsum, and lime showed the most significant correlations with the vegetative traits and essential oil compounds of Nepeta eremokosmos. The conservation status of Nepeta eremokosmos in Iran is Critically Endangered, based on its occupancy of 1.250km2 and the extent of its occurrence in 69,862km2. Plant species' essential oils have biological effects that are influenced by their effective substances, which can be affected by both genetic pathways and environmental factors. The plant's chemical performance can be maximized by selecting the most appropriate chemotype based on specific goals and providing optimal environmental conditions. According to the research findings, Nepeta eremokosmos prefers steppe habitats with higher essential oil content and compounds with higher antioxidant properties. Thus, this habitat is deemed suitable for conserving and cultivating Nepeta eremokosmos.