Morphological characteristics, microsatellite fingerprinting and determination of incompatibility genotypes of Sicilian sweet cherry cultivars

Sicily has extensive germplasm of diploid sweet cherry (Prunus avium L.) that has not been well studied. In this investigation, 39 cherry accessions, selected from collections and farms, were analysed using molecular markers and characterised for various morphological and other agronomic characters such as flesh colour, fruit size, quality and, in some cases, ripening periods. Thirteen Simple Sequence Repeat (SSR) primer pairs, as well as two primer pairs for the incompatibility (S) locus, which amplified across the first intron of the S-RNase gene and across the intron of the SFB gene, were used in three multiplexed reactions to analyse the accessions. The number of alleles per SSR locus ranged from four to 11 (mean 7.2). Twelve S-alleles were found. Allele S-4, which has been reported to be common in sweet cherry, was absent from the Sicilian germplasm and alleles S-16 and S-22 were frequent, although previously reported largely in wild populations. The accessions were assigned to their incompatibility groups. A UPGMA dendrogram was constructed and revealed possible synonyms. The set of SSR primers amplified unique fingerprints for 27 accessions, while twelve fell into six non-distinguishable groups. This approach could be used for comparing cultivars and wild accessions from other regions, and for establishing a database of this important species for breeding and conservation purposes. Several accessions useful for breeding are reported.