Danish apple cultivars: genetic diversity, parentage and breeding potential

Abstract
We made a genetic analysis of about 500 apple cultivars, which either originate
from Denmark or have been of greater importance in Denmark. To study the diversity and parentage among the cultivars, 15 SSR markers were used. A new PCR-based protocol for identification of S-alleles was developed and used to study the S-alleles among cultivars. The protocol using general S-locus primers and digestion with two restriction enzymes, for fragment analysis on an automated DNA sequencer fastens the process and gives an accurate estimation of fragment lengths. The ploidy level was determined using flow-cytometry. All cultivars were distinguishable by the SSRmarkers though Danish originating cultivars did not form a group distinct from foreign cultivars. The parentage of several well-known cultivars was revealed.