Investigation of genetic relationships and possible origins of citrus from Cyprus on genetic resources

In this thesis, the genetic relationships of 70 citrus genotypes selected from the island of Cyprus, along with 15 commercially cultivated citrus genotypes, were analyzed using SSR and ISSR marker systems and their genetic relationships were investigated. Pomological and morphological analyses were also conducted to gain a deeper understanding of the characteristics of the selected genotypes and the results were evaluated together with molecular analyses. As a result of the molecular studies, the SSR analysis revealed a polymorphism rate of 100%, with Polymorphism Information Content (PIC) values ranging from 0.48 to 0.93; while ISSR analysis showed a polymorphism rate of 89.80%, and PIC values between 0.34 and 0.93. The results from both marker systems were combined; the genetic distance among genotypes ranged from 0.34 to 0.91, and the dendrogram grouped the genotypes into two main clusters. The results indicate a significant level of variation among the selected genotypes. The PCoA graph shows that the greatest genetic distance was observed between genotypes AEL2 and AET46, while the closest relationship was found between AET15 and AET24. In terms of pomological and morphological characteristics, the genotypes AET38, AET44, and AET34 (sour oranges), AEP10, AEP7, and AEP11 (oranges), as well as AEL14 and AEL10 (lemons), stood out based on the evaluated parameters and are considered promising candidates. The findings and selected genotypes discussed in this thesis will serve as valuable resources and guidance for future citrus breeding research. Keywords: Citrus, genetical resources, Cyprus Island, molecular markers, phylogenetic