| چکیده انگلیسی مقاله |
Extended Abstract
Introduction and Objective: The genetic diversity of plant species and their relationship with wild species is very important to improve the yield of crops..The first step in the improvement of medicinal plants is to identify and collect endemic genotypes.Endemic genotypes are very important in the selection of cultivars due to their adaptability to the climate of the region. Mentha longifolia is one of the important endemic medicinal plants of Iran, which is used in various pharmaceutical, food and cosmetic industries. Essential oil, phenolic compounds, flavonoids and other compounds such as steroids and ceramides are important chemical compounds in oregano plant. In this study, morphological diversity, essential oil and antioxidant activity of 20 Mentha longifolia genotypes in West and East Azerbaijan provinces were investigated. The aim of this research, on the one hand, is to know the potential and range of diversity of Menta longifolia genotypes in its natural habitats in West Azarbaijan and East Azarbaijan provinces. On the other hand, the introduction of regions with superior genotypes in terms of these traits is for use in breeding programs.
Material and Methods: The collection of plant samples from some areas of two northwestern provinces of Iran (West Azerbaijan and East Azerbaijan) was done in the spring of 2022. In order to evaluate the morphological traits of the plant in the flowering season, 11 quantitative traits of the plant including plant height, inflorescence length, crown diameterstem diameter, internode length, leaf length, leaf width, number of leaves, number of inflorescences, fresh weight, dry weight and the number of sub-branches were evaluated. After drying the plant samples, essential oil extraction was done using a clonger, and the essential oil samples were transferred to Urmia University Jihad to identify compounds by gas chromatography. Extraction of plant samples was done by ultrasonic method .Antioxidant activity was evaluated by DPPH method. All the obtained data were analyzed with three repetitions and based on a completely random design using SPSS software .LSD test was used to compare the mean data. Data clustering was done based on Ward's method and Euclidean distance square measure. Principal component analysis was performed on the data .Also, in this study, correlation between studied traits was done by R software.
Results: The results of analysis of variance showed that the genotypes collected from different regions have significant differences in terms of plant height, inflorescence length, crown diameterstem diameter, internode length, leaf length, leaf width, number of leaves, number of inflorescences, fresh weight, dry weight and the number of sub-branches are investigated (P < 0.01). The results of the analysis of the percentage and chemical composition of the essential oil showed that the type of genotype had a significant effect on the amount of these compounds in different genotypes of Mentha longifolia (P < 0.01). Among the studied genotypes, the highest percentage of essential oil and the amount of Trans-Caryophyllene and Germacrene D compounds were found in G18 of Iranq region of Tabriz, also the highest amount of Alpha-Terpineol and Spathulenol was found in G16 of Aghajari region of Maragheh. Also, there was a significant difference between different genotypes of mint in terms of antioxidant activity. The maximum amount of antioxidant activity (80.81%) was observed in G3 of Hachesu area in Shahindej. Based on Ward's cluster analysis, the genotypes were divided into three main groups. G1 alone was placed in a separate group due to the high content of Spathulenol and high antioxidant activity. The second group, which includes most of the genotypes (G2, G3, G5, G16, G19, G17, G20, G12, G14, G4, G6, G8, G11, G13, G9, G7 and G10), has a moderate amount of morphological traits, essential oil components and antioxidant activity. G15 and G18 genotypes were placed in the third group. The prominent features of these genotypes were high values of length and number of inflorescences, length and width of leaves, number of leaves, fresh and dry weight of the plant, number of sub-branches, percentage of essential oil, alpha-Humulene, trans-Caryophyllene and GermacreneD and antioxidant activity.Using principal component analysis, 21 primary variables were determined in the form of two principal components.The first component explained 40% and the second component 19% of the total variance. The results of correlation analysis showed that there was a positive and significant correlation between the percentage of essential oil and some morphological traits, the percentage of essential oil and the amount of Germacrene D, trans-Caryophyllene, beta-Farnesene and isomenthon, as well as antioxidant activity and morphological traits.
Conclusion: The findings of this study showed that G15 belonging to Maragheh with an altitude of 1776 m had the highest number of leaves, length and width of leaves, fresh weight, dry weight and number of sub-branches, internode length and number of inflorescences compared to other genotypes.Therefore, it can be said that this genotype has priority for breeding, domestication and crop cultivation projects and is suitable for its introduction to the market as a medicinal plant.In addition, the results showed that the highest percentage of essential oil and the amount of compounds such as Germacrene D, Trans-Caryophyllene, Spathulenol, Beta-Farnesene, Alpha-Terpineol were obtained in genotypes with high altitudes.
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