SSR Marker-Based Fingerprinting for Sour Cherry (Prunus cerasus) Genetic Resources Identification and Management

The genetic diversity of sour cherry (Prunus cerasus L.) germplasm and relationships among accessions in a germplasm collection is crucial for development of a plant material maintenance strategy. Fifty sour cherry accessions maintained at the genetic resources collection of the Latvia State Institute of Fruit-Growing (LIFG) were evaluated using 26 SSR markers. Two sets of SSR markers were applied: 16 markers approved by ECPGR Prunus WG and the set of 10 markers previously chosen by the LIFG. Successful amplification was observed for 25 of the tested markers (except PS05C03). Marker EMPA026 showed a monomorphic band pattern, but the other tested SSR markers were highly polymorphic, with 4 to 20 alleles per locus. Heterozygosity and gene diversity values ranged from 0.520 to 1.000 and 0.539-0.865, respectively, while discrimination power per locus varied from 0.307 to 0.918. Higher average values of allele number, observed heterozygosity as well as gene diversity were observed for the LIFG marker set; however, average discrimination power was identical for both marker sets. Special interest was paid to the clones of landrace 'Latvijas Zemais', which is the most important commercial cultivar in Latvia. In total 25 clones collected throughout the country were analysed to evaluate their genetic relatedness as well as for detection of identity. Two genetically identical clones of 'Latvijas Zemais' were found that should be taken into account in the maintenance strategy. In general, clones of 'Latvijas Zemais' showed high mutual genetic similarity and distinction from other Latvian sour cherry cultivars as well as cultivars developed in other countries.