S‐allele identification by PCR analysis in sweet cherry cultivars

Gametophytic self‐incompatibility, governed by the S‐locus, operates in sweet cherry. The knowledge of the S‐genotype of sweet cherry cultivars is therefore essential to establish productive orchards by defining compatible combinations. The isolation of sweet cherry S‐R Nases has allowed the use of different molecular techniques to characterize the S‐genotypes of sweet cherry cultivars. Previously, incompatibility group assignment could only be carried out on mature trees through pollination tests. In this work, PCR analysis with primers designed on the conserved sequences of sweet cherry S‐R Nases has been used to characterize the S‐genotype of 71 sweet cherry cultivars, including 26 cultivars whose S‐allele constitution had not been previously described. This approach has allowed the detection of alleles that had not been amplified by PCR before, to identify six putative new S‐alleles, to define three new self‐incompatibility groups and to compile the standards for a PCR‐based S‐allele typing method in sweet cherry.