Genetic and morphological variation in Iranian olive (Olea europaea L.) germplasm

Olive cultivars with specific characteristics have been developed thanks to Iran’s particular climatic conditions and long-term olive cultivation. The genetic variation and relationships among 40 olive cultivars, as well as 17 unknown genotypes from the national olive collection orchard at Tarom Research Station, Zanjan, Iran, were evaluated using SSR markers. Using 10 microsatellite primer pairs, 43 polymorphic bands were obtained on 57 olive genotypes. In addition to molecular markers, 14 morphological traits were measured in all olive genotypes. Based on discriminant and cluster analysis, the group of Iranian genotypes showed the greatest genetic distance from Spanish, Greek, Syrian, Italian and French groups. Based on cluster analysis using molecular and morphological data, most of the unknown genotypes showed high genetic similarity with genotypes from Spain and Syria. Despite the high genetic variation among cultivars in each group, geographical origin had significant impact on observed variability using Shannon’s information index and polymorphism information of olive accessions. Climatic conditions in Iran, which are very different from conditions in Mediterranean countries, probably played a significant role, although this needs to be investigated further. The lowest mean of Shannon’s index (0.76) for Iranian accessions indicated limited gene exchange with other genetic resources worldwide. The different genetic background of Iranian olive cultivars may help breeders access new and valuable genetic resources for national olive breeding programs