Molecular Characterization of Citrus Cultivars Using DNA Markers

Twenty five SSR primers were used to assess polymorphism in twelve genotypes which belong to four species and one hybrid of citrus. A total of 116 clear and reproducible amplified bands were obtained, out of which 103 were polymorphic. The numbers of amplified DNA bands per primer were ranged from 2 to 9 (Molecular size from 100–1200 bp) with an average of 5.27. Percentage polymorphisms ranged from 75–100 with an average of 89.78% across the genotypes and polymorphism information content (PIC) values from 0.25 to 0.68 having an average of 0.41. The primers clustered the citrus genotypes into two major groups, and further into many sub groups. The results revealed by the two and three dimensional principle component analysis further insured these groupings. The similarity matrices ranged from 0.439 (Cleopatra and Blood Red) to 0.801 (Baramasi and Badri lemon), with an average of 0.582 across all the genotypes. Some markers produced unique alleles in specific genotypes which could be used to discriminate them from the other.