Identification of genetic diversity among mutant lemon and mandarin varieties using different molecular markers

Mandarin (Citrus reticulate Blanco) and lemon (C.limon L.) are among the most cultivated Citrus species in the world.Amongdifferent approaches, gamma radiation is widely used to induce mutations in citrus breeding studies. Gamma radiation causes DNAdamage, randomly inducing several mutations in the genome. Molecular techniquesarewidely used to detect such induced mutationsand genetic diversity in plants.In this study, simple sequence repeats (SSR), inter-simple sequence repeat (ISSR) and single-strandconformation polymorphism (SSCP) markers were used to detectthe induced mutations andgenetic diversityin someirradiatedmandarin and lemon genotypes in comparison with standard citrus varieties. The irradiated genotypes used in this study derived frompopulationsthat had been originally obtained with gamma radiation with different gray doses applied on Yerli Mandarin and AntalyaYerliYuvarlak lemon varieties. Out of 82 primers (22 SSCP, 30 ISSR and 30 SSR) tested, 55 primers (9 SSCP, 24 ISSR and 22 SSR primers)successfully amplified a total number of 363 amplicons.A single band with an approximate size of 500 nucleotides was determinedusing the primer ISSR 868 as differentiating between seedy parent and irradiated seedless mandarin genotypes. The polymorphisminformation content (PIC) values of SSCP, ISSR, and SSR markers ranged from 0.61–0.99, 0.31–0.96, and 0.33–0.96, respectively. Clusteranalysis classified lemons and mandarins into 2 subgroups as mutant and commercial lemon genotypes. ISSR markers were foundto be more effective to determine the genetic differences among the varieties in comparison to SSCP and SSR markers. The resultsclearly showed that SSCP, SSR and ISSR markers are important tools to distinguish mutant genotypes andconfirmed their usefulness forphylogenetic studies.