Evaluation of Genetic diversity in Hypericum L.: A high value medicinal plant from Northern of Iran using SCoT molecular markers

Background and objectives
Hypericum (Guttiferae, Hypericoideae) is a large genus comprising almost 500 species, primarily herbs, shrubs, and a few trees, and is classified into 36 taxonomic sections. Iranian species of this genus primarily grow in the north, northwest, and center of Iran, forming floristic elements of the Hyrcanian mountainous areas, as well as Irano-Turanian, Mediterranean, and Zagros elements. These species are of medicinal, commercial and horticultural value. SCoT morphological and molecular data were used to study the genetic diversity and population structure of six species of the genus Hypericum. One of the objectives of the present study is to determine whether SCoT markers can effectively distinguish Hypericum species from each other.
Materials and Methods
A total of 58 individuals from geographical areas belonging to six different species of the genus Hypericum, including: H. lysimachioides; H. asperulum; H. scabrum; H. hirtellum; H. perforaturm and H. triquetrifolium were sampled in the provinces of East Azerbaijan, Lorestan, Kermanshah, Isfahan and Hamedan in July and August 1400-1403. For morphological studies, 5 to 12 samples of each species were used. A total of 24 morphological traits (16 qualitative traits, 8 quantitative traits) were examined. PCoA was used to group the species. For SCoT analysis, 58 plant accessions (five to twelve samples from each population) belonging to six populations with different ecological characteristics were used. CTAB method was used to extract genomic DNA. 10 SCoT primers were used for this study, which produced 135 polymorphic bands. UPGMA cluster analysis was performed to analyze molecular data and determine genetic relationships.
Results
The biplot diagram of the distribution of Hypericum species based on the first and second principal components of PCA using morphological characteristics placed plant samples of each species together and formed separate groups. Accordingly, the greatest differentiation was observed between the species H. triquetrifolium, H. hirtellum and H. scabrum. 135 amplified polymorphic bands were generated across 6 Hypericum species. The size of the amplified fragments ranged from 100 to 3000 bp. The highest and lowest number of polymorphic bands was 22 for SCoT-3 and 7 for SCoT-15, on an average of 13.5 polymorphic bands per primer. The PIC of the 10 SCoT primers ranged from 0.37 (SCoT-17) to 0.64 (SCoT-16) with an average of 0.50 per primer. MI of the primers ranged from 3.44 (SCoT-16) to 5.85 (SCoT-15) with an average of 4.7 per primer. EMR of the SCoT primers ranged from 6.22 (SCoT-15) to 11.55 (SCoT-1) with an average of 9.5 per primer. Molecular variance analysis showed that 67% of genetic variation was between species and 33% within species. Cluster analysis was performed using the genetic distance matrix based on the Jacard distance, using the UPGMA method, and the species were placed in separate clusters.
Conclusion
In this study, the efficiency of the SCoT marker in the plant genome and its role in the genomic diversity of H. perforatum species was used. The results of this study showed a high level of genetic diversity and gene flow in the populations of 6 Hypericum species and were able to divide the studied species into separate groups using both morphological and molecular characteristics, and we did not encounter intermediate forms in this differentiation. The results of the SCoT marker data were in good agreement with the morphological data. These results showed that the SCoT marker can be used in the classification of Hypericum species and this information can be useful in strategies for species identification, plant breeding and germplasm conservation programs.