More Harmonization Needed for DNA-Based Identification of Apple Germplasm

Considerable efforts have been made to provide gene bank accessions with DNA-based identification profiles, especially for expensive collections that are maintained in the field like fruit trees. Primers have been developed for numerous SSR loci (microsatellite DNA), and have proved very useful for discrimination among genetically unique fruit tree cultivars. In most cases it is, however, impossible to make valid comparisons across studies since different sets of loci are used in different laboratories. This is a major problem since research and breeding must be based on correctly identified gene bank material. Sets of SSR loci and standard genotypes have been appointed by ECPGR for pear and cherry, and a proposal has also been made for apple. Here, we will present a compilation of the loci used in major SSR-based screenings of apple and also discuss some issues concerning SSR markers and other DNA-based methods.