Genetic diversity and geographic dispersion in Thymus spp. as detected by RAPD [Random Amplified Polymorphic DNA] markers
2015
Yousefi, V. | Najaphy, A. | Zebarjadi, A. | Safari, H.
Thyme, as an aromatic medicinal plant and a perennial and woody herb Lamiaceae has commercial, pharmaceutical and perfumery potentialities. Thymus is taxonomically a very complex genus with high frequency of hybridization and introgression among sympatric species, and some species of this herb are endemic to Iran. From the chemical point of view, important biochemical components such as thymol and carvacrol are known in thyme. In the present study, 13 Thymus spp. accessories collected from different geographic areas of Iran along with one accession from England (Thymus vulgaris) were analyzed by Random Amplified Polymorphic DNA (RAPD) markers using 20 primers to discover genetic polymorphism. A total number of 510 bands were detected from 20 RAPD primers, of which 483 (94.315) were polymorphic with an average of 24.15 polymorphic bands per primer. The size range of the amplified products was 200-4000 bp. UPGMA cluster analysis was carried out using Jaccard similarity coefficients based on PAPDS. The dendrogram obtained from the method classifies the 14 thymes accessions into four major groups. Scatter biplot based on principal coordinate analysis (PCoA) also revealed four groups and confirmed the results of clustering method with some minor disagreements. The accessions were relatively grouped according to the location where they had been collected. The molecular variation assessed in the study could elucidate largely geographic dispersion of the thyme accessions, and in combination with biochemical characteristics, can be useful to improve the efficiency of selection and breeding programs.
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