An Overview of S-Genotype Diversity in Sweet Cherry Landraces Grown in the Central Region of the Republic of Serbia

Identification of the S-genotypes in landraces is a crucial step in the molecular characterization of Serbian autochthonous sweet cherry germplasm. It is also of enormous significance for breeders and growers, as this fruit species exhibits a gametophytic self-incompatibility, controlled by the multi-allelic two genes of the S-locus. The aim of this study was to summarize known information and reveal new data on the S-alleles in 23 sweet cherry landraces originating in the Republic of Serbia. The use of polymerase chain reaction (PCR) with consensus primers for the second intron of S-RNase, primers specific for S-RNase and certain SFB alleles, along with DNA fragment analysis using fluorescently labelled forward primers to amplify both the S-RNase first intron and the SFB intron, revealed 10 alleles (S1 to S6, S9, S12, S13 and S22) that generated the following 13 S-genotypes: S1S2 (one landrace), S1S4 (one landrace), S1S5 (one landrace), S2S3 (four landraces), S3S4 (two landraces), S3S5 (two landraces), S3S6 (three landraces), S3S9 (two landraces), S3S12 (two landraces), S4S5 (one landrace), S4S13 (one landrace), S5S22 (one landrace) and S6S9 (two landraces). The most frequent S-allele and S-genotype in this sweet cherry material were S3 and S2S3, with occurrence frequencies of 32.6% and 17.4%, respectively. Based on the obtained results, the sweet cherry landraces were assigned to 12 incompatibility groups and one group of universal donors (‘0’). These results provide important information about their cross-compatibility and the diversity of the S-locus in Serbian sweet cherry germplasm.