Polymorphism in Random Amplified and Nuclear rDNA Sequences Assessed in Certain Apple (Malus × domestica Borkh.) Cultivars

Eigth apple (Malus × domestica Borkh.) cultivars: ‘Delikates’, ‘Cortland’, ‘James Grieve’, ‘Lired’, ‘Jonathan’, ‘Golden Delicious’, ‘Jonagold’ and ‘Idared’ were characterized by two different molecular tools. These included analysis of the distribution of RAPD markers and length variability of the SSU, 5.8S, LSU and ITS region of the nuclear rRNA genes assessed in PCR reactions with different combinations of ‘universal’ primers. RAPD analysis was performed with 17 out of 24 RAPD primers tested. Those amplified a total of 183 loci (872 amplicons) out of which 34 (18.5%) were monomorphic, 128 (69.5%) were polymorphic and 22 (12%) cultivar-specific. Cultivar-specific RAPD products were detected for each apple cultivar. Amplification of the rDNA sequences showed variability. Fifty-four amplicons were generated in the experiment including 14 monomorphic, 26 polymorphic, and 14 cultivar-specific products. Altogether 232 amplicons were generated, whose length ranged from 220 to 940 bp. The analysis of dendrograms constructed on the basis of the analysis of RAPD genetic profiles and profiles amplified on rDNA matrices showed their significant correlation (Mantel test: r(AB) = 0.430; p-value (Two-tailed) = 0.024), which proves that the used methods correctly presented variability within the examined cultivars, and the molecular markers identified in the study can be considered appropriate.