Genetic structure of Iranian olive cultivars and their relationship with Mediterranean's cultivars revealed by SSR markers

• Bayesian analysis showed separation of olive trees of North of Iran from West and East Mediterranean olive cultivars.
• Genetic structure revealed admixture allelic compositions among Mediterranean olive cultivars different from Iran genotypes.
• High genetic variations among Iranian studied cultivars show the presence of potentially rich gene pool in the country.

A collection of 52 local Iranian olive genotypes (North and south of Iran) and 36 olive cultivars from Mediterranean countries were studied in order to determine the genetic structure and their relationships. Thirteen primer pairs of microsatellite loci were selected that were known to be discriminating from previous study on olive. Polymorphic Information Content values ranged from 0.51 to 0.95. The Gst analysis for SSR loci revealed that some of the loci are more common while, some other loci are present in certain populations and show limited distribution among populations. Analysis of molecular variance (AMOVA) revealed that 11.71% of genetic variation attributed to differences between geographical regions while 88.29% came from variation in within regions (P < 0.05). Pairwise Fst test revealed significant differences (P < 0.05) between populations except between West and East Mediterranean populations. Neighbor Joining cluster analysis grouped the olive cultivars in two distinct clusters separating, olive genotypes located in North of Iran from the rest of olive cultivars studied. STRUCTURE and K means analyses showed the presence of distinct groups in olive trees and revealed variability in allelic compositions and their frequency between Iranian and West and East Mediterranean olive cultivars. The results of Bayesian clearly revealed that due to frequent occurrence of gene flow, the West and East Mediterranean olive cultivars had lower Fst values compared to the other population groups. In present study, genetic structure revealed admixture allelic compositions among Mediterranean olive cultivars different from Iran genotypes.