S-alleles analysis of cultivars from Ukrainian apple germplasm collection

Self-incompatibility in apple (Malus × domestica Borkh.) is an agriculturally important trait regulated by an S-locus with a number of self-incompatibility alleles. In Ukraine, until now, the compatibility or incompatibility among apple genotypes has been discerned through cross-pollination experiments that have been used for the choice of suitable pollinators, which is labor intensive and motivated the current study. Objective of our study was to determine S-locus genotypes of apple cultivars from the Ukrainian germplasm collections, including traditional heirloom cultivars and modern cultivars, as well as advanced selections of Ukrainian origin. Some important international cultivars of known allelic composition were used as controls. The S-alleles were identified using previously published protocols based on PCR amplifications, and where necessary, digestion of PCR product with restriction enzymes. Thereby the S-allele genotypes of 74 unique apple cultivars were revealed. Knowledge of S-allele genotypes is valuable for planning crosses within breeding programmes, selection of suitable pollinators, and management of commercial orchards in Ukraine.