Genetic Insights into S-Haplotype Determination in Sour Cherry Cultivars Released at the Fruit Research Institute, Čačak

Sour cherry (Prunus cerasus L.) possesses considerable potential to maintain a prominent position in the fruit-growing structure of the Republic of Serbia, owing to both its economic importance and long-standing cultivation tradition. Breeding activities on this tetraploid species at the Fruit Research Institute, Čačak (FRI) have a decades-long background, resulting in five cultivars released to date – ‘Čačanski Rubin’, ‘Iskra’, ‘Nevena’, ‘Sofija’ and ‘Šumadinka’. Identification of S-haploty pes in released and parental cultivars represents a crucial step in their molecular characterisation and is highly relevant for both breeders and growers, as sour cherry also exhibits a gametophytic self-incompatibility system controlled by two multi-allelic genes located at the S-locus. The aim of this study was to compile existing knowledge and present new data on S-haplotypes (S-RNase and SFB alleles) of parental and released cultivars from the FRI sour cherry breeding programme. S-haplotype identification was carried out using the polymerase chain reaction method, employing three consensus primer pairs specific to the first and second S-RNase introns, allele-specific primers for both S-RNase and SFB genes, and genetic tests to detect stylar-part and pollen-part mutants. This study determined the complete S-haplotype of ‘Čačanski Rubin’ (S1S4S13’S36a) and, for the first time, identified three S-haplotypes in ‘Heimanns Konserven Weichsel’ (S9S13S36b2). Furthermore, the pedigrees of FRI-released cultivars were analysed based on S-locus polymorphism.