Genetic diversity evaluation of lemon balm (Melissa officinalis L.) ecotypes using morphological traits and molecular markers

Genetic diversity of 12 lemon balm ecotypes was evaluated using agronomic traits as well as ISSR and RAPD markers. Results of analysis of variance showed high diversity among the studied ecotypes. Cluster analysis using UPGMA method grouped the ecotypes into three different groups based on the agronomic traits. Twelve ISSR primers created 106 polymorphic bands among the studied ecotypes. An ISSR primer called UBC813 with 16 bands and UBC811, UBC815 and UBC817 primers with 15 bands had the highest number of polymorphic bands and UBC825 with 8 bands had the lowest number of polymorphic bands. In addition, 10 RAPD primers, created 127 polymorphic bands, among them OPA-01 with 22 bands and BB13 and OC4 primers with 19 and 18 bands had the highest number of polymorphic bands. In contrast, OS-03 and OB20 markers had the lowest number of polymorphic bands with 14 and 15 bands, respectively. Polymorphism information content (PIC) value ranged between 0.33 to 0.37 for ISSR markers and 0.31 to 0.37 for RAPD markers. Marker index (MI) value ranged between 1.11 to 4.38 for ISSR markers and 1.85 to 5.28 for RAPD markers. Cluster analysis using UPGMA method based on ISSR and RAPD markers results clustered the studied ecotypes into three and two different groups, respectively, by which the percentage of similarity of the two grouping method was about 50%. Grouping the ecotypes based on both molecular markers and agronomic traits matched each other about 40 to 60%.

Cluster Analysis, Genetic Diversity, ISSR, RAPD