Genotypic and phenotypic diversity in Finnish cultivated sour cherry (Prunus cerasus L.)

The Finnish national sour cherry germplasm collection was established in the end of 1980s following collection missions in Southern Finland. The original plantation consisted of 122 trees representing 77 accessions of locally adapted cherry material. Cultivar names of the collected samples were not known, and they were registered according to the collection site. Phenotypical observations according to the Nordic Genebank instructions were recorded in 1992, 1993 and some repetitions were made in 2003. In 2005 leaf samples were collected from the 52 still remaining accessions for a microsatellite (SSR) DNA marker analysis. DNA analysis distinguished 28 genotypes within the studied material. Two large groups of accessions sharing identical genotype, consisting of 18 and 20 accessions, were detected, one in the amarelle and one in the morello-cultivar group, respectively. Several cultivar group specific SSR markers were found. Clustering analysis of the phenotypical characteristics supported the division into two cultivar groups. Replicate trees of one accession, or accessions representing one SSR genotype, clustered together only occasionally indicating some level of plasticity in the observed descriptors. Our findings indicate that only a few sour cherry clones have been successful and commonly distributed in Finland. The results were taken into account when selecting accessions for long term conservation in the national germplasm collection.