Genetic structure and relationships among Melissa officinalis accessions using AFLP markers

Melissa officinalis, a member of the Lamiaceae family, is one of the most important medicinal herbs that are applied in different fields of industry worldwide. Genetic diversity and structure of 21 M. officinalis accessions were examined using amplified fragment length polymorphism (AFLP) markers. For this purpose, 15 primer combinations generated a total of 1592 scorable bands, of which 1402 bands were polymorphic. The primer combination P-66/M-48 showed the highest markers polymorphism values (PIC = 0.28, DI = 0.34, and I = 0.51), while the lowest values (PIC = 0.17, DI = 0.20, and I = 0.32) is obtained from the P-14/M-49 combination. The marker index (MI) values with an average of 18.46 showed high values for both primer combinations E/M and P/ M. All of the accessions, based on Neighbor-Net clustering method and structure analysis, are assigned to five clusters; with the maximum genetic dissimilarity of 0.51 belonging to accessions from Gilan (Roodbar and Damash). In addition, the principal coordinate analysis (PCoA) data confirmed the results of the clustering. In this study, the genetic distance was not often related to geographical distance. More likely the relationship among them is due to seed dispersal through human interactions. Our findings indicate that high genetic diversity of M. officinalis accessions provides important baseline data and a better understanding of conservation, management, and collection strategies for germplasm of this species.