The use of microsatellites to analyze relationships and to decipher homonyms and synonyms in Azorean apples (Malus × domestica Borkh.)

The objective of this study was to exploit the molecular and morphological variability present in Malus domestica to clarify the confused characterization of apple plantations in the Azores. Most Azorean apples are grown in orchards. They are usually given a local name, and sometimes the same name is used for different cultivars and varieties which share morphology and should be known by different names. Two-hundred samples of apples cultivated in the Azores were analyzed by use of ten microsatellites. The total number of alleles per locus ranged from 10 to 24, with a mean of 15.2. Heterozygosity was high, reflecting the high variability of the samples. Expected heterozygosity varied within a narrow range, from 0.74 to 0.88, whereas observed heterozygosity ranged from 0.41 to 0.98. The high genetic variability contributed to the high discriminating power, which ranged between 0.84 and 0.93. These microsatellites were used to unambiguously discriminate most of the tested apple cultivars on the basis of their allelic profiles. The rooted UPGMA tree organized most of the samples into thirteen main clusters, often with high bootstrap values. We identified 60 synonyms and 32 homonyms among the samples. Moreover, it was possible to relate each individual to its originating population and detect likely parent–offspring groups.