Use of Random Amplified Polymorphic DNA Analysis to Detect Genetic Variation in Pyrus Species

Pyrus communis L. is the most important pear species for European production. Very few cultivars satisfy standards for fruit quality and clonal fidelity; thus, accurate verification of cultivar identity for checking propagation material and patent protection is important. We evaluated the randomly amplified polymorphic DNA (RAPD) technique for its ability to identify genetic differences among standard pear (Pyrus communis L.) cultivars, William, Passa Crassana, and Conference, and 3 gamma-ray induced variants. To identify genotype-specific markers, we used thirty 10-mer and two 11-mer sequences, annealing temperatures from 36-45°C, 2 Taq polymerases (AmpliTaq and Stoffel fragment, both from former Perkin Elmer Cetus), and 2-4 replicate amplifications. Of the 32 primers (30 from Operon Technologies, Alameda, CA, USA), very few distinguished William from Passa Crassana, and only 1 could clearly differentiate all 3 cultivars. Two primers that did not reveal polymorphisms when used singly, generated polymorphic patterns that distinguished standard from gamma-ray-treated material when used in combination. We show that RAPD analyses can discriminate pear genotypes and suggest this technique as a reliable and inexpensive method for marker-facilitated screening of propagation material and for patent protection.