Identification of self(in)compatibility genotypes and microsatellite marker based fingerprinting of traditional italian sweet cherry accessions

Italy is one of the main European sweet cherry producers and it has a rich germplasm, including many minor local varieties that have not been well studied or used in breeding programmes. Sweet cherry is self-incompatible, with few exceptions; its incompatibility is controlled by a multi-allelic S locus, which is gametophytically expressed. The knowledge of S-alleles and cross-incompatibility groups of sweet cherry genotypes and cultivars is important for growers and breeders. In this work we analysed 48 traditional sweet cherry varieties and cultivars, mainly from Calabria and Emilia Romagna regions, together with eight Sicilian cultivars and the standard set of reference genotypes proposed by the European Collaborative Programme for Genetic Resources (ECPGR) Prunus group (Clarke and Tobutt, 2009), using molecular markers. Two consensus primer pairs for the incompatibility (S) locus, and eight microsatellite (SSR) primers, recommended by the ECPGR, were used in multiplexed reactions to characterise the accessions. Twelve different S-alleles were detected. S3, S6 and S13 alleles were the most common. Accessions were assigned to incompatibility groups. The chosen SSRs were able to discriminate most of the accessions and to discover duplicates and synonyms. Our results are useful for efficiently design orchards and planning crosses for future breeding programmes. The usefulness of some accessions for breeding is discussed.