Development of a molecular marker for self-compatible S4 haplotype in sweet cherry (Prunus avium L.) using high-resolution melting

Sweet cherry (Prunus avium L.) has stylar gametophytic self-incompatibility, which is controlled by the multi-allelic S-locus and encompasses the highly polymorphic genes for the S-ribonuclease (S-RNase) and S-haplotype-specific F-box (SFB), which are female and male determinants, respectively. The self-compatible mutant SFB4 corresponds to an allele variant of SFB4 and presents a frameshift mutation. Even though male-determinant molecular markers can discriminate between SFB4 and SFB4 alleles, the methods required are laborious, time-consuming and expensive, and not suitable for massive analysis and integration into breeding programmes. Our aim was to develop molecular markers for the evaluation of self-compatibility alleles in sweet cherry, that could be used as a high-throughput screening strategy to identify SFB4 and SFB4 alleles, based on a marker for male determinacy. Our results were consistent using primers flanking the mutation responsible for the SFB4 allele. We designed a specific molecular marker and confirmed it in sweet cherry commercial varieties. This new molecular marker is feasible for self-compatibility alleles in the male determinant in sweet cherry-assisted breeding programs.