Genetic variability of commercially important apple varieties (Malus x domestica Borkh.) assessed by CDDP markers

Apple stand on the top of the most desirable and most produced fruit species in the world. Despite enormously wide genetic
diversity among existing apple varieties, the current market is mostly oriented on several cultivars of commercially attractive
traits. For the preservation of genetic resources and for breeding programmes, the evaluation of genetic diversity is fundamental.
Number of marker systems have been developed and adopted in the assessment apple germplasm. In the present study, CDDP
marker technique was used to analyse polymorphism within the genomes of fifteen apple varieties which are of large commercial
use. Five primer combinations were used in the PCR amplification: WRKY-F1/WRKY-R1, WRKY-F1/WRKY-R2, WRKY-F1/WRKY-R2B,
WRKY-F1/WRKY-R3 and WRKY-F1/WRKY-R3B. All primer combinations produced polymorphic amplification patterns. In some
primer combinations, identical amplification profiles were observed in few varieties, but amplification patterns of all combinations
merged were specific for each apple variety. Identical profiles were only seen in Red Delicious and Granny Smith in F1/R1 primer
combination, May Gold and Paula Red, and Selena and Melodie in F1/R2 primer combination and May Gold and Paula Red when
F1/R3B primers were used. Based on the CDDP markers, UPGMA algorithm assessed cultivars Paula Red and May Gold as the
most similar (with similarity value of 0.909), whereas Gloster and Ambrosia showed to be the least similar within the analyzed set
(similarity value of 0.200). The study proved CDDP markers to be suitable tool to produce polymorphic amplification patterns in
apple genotypes.