Genetic diversity and molecular characterization of olive cultivars (Olea europaea L.) in Iraq using ISSR markers

This study used ten different Olea europaea L. genotypes, including Ashrasi, Bashiqa, Manzanilla, Dakel, Al-Khudairi, Darmalali, Sorani, Qaisi, Nabali, and Ascolano. The genotypes were selected from seven sites representing the major areas of olive production and cultivation in Iraq. Genetic relationships among the 10 examined olive cultivars were determined using ISSR analysis, which revealed that 10 primers were highly efficient, generating 98 bands, 64 of which were polymorphic, yielding a mean polymorphism rate of 64.7%. These findings reveal significant genetic differentiation among the olive cultivars under study. Genetic similarity coefficients ranged from 0.11 to 0.83, indicating a broad spectrum of diversity. The Ashrasi cultivar was the most genetically distinct, suggesting it may be useful for enriching genetic diversity. In contrast, high genetic similarity was observed between Qaisi and Dakel, and between Darmalali and Al-Khudairi. These results were also supported by the dendrogram, which separated the cultivars into two major groups: one with higher similarity and the other with greater evolutionary distance, with Ascolano forming a separate branch, indicating its unique genetic identity