Peculiaritats al·lèliques del locus S de les cultivars mallorquines d’ametller

The examination of the allelic diversity of the locus S in ten almond cultivars from Majorca has shown the presence of the Sf allele in four of them, as well as the presence of five new alleles non identified so far. Although the Sf allele has been described as responsible for the expression of self-compatibility in almond, it has been recently shown that this allele has two different phenotypic expressions. As a consequence, this allele cannot be always considered an index for self-compatibility of the genotypes harbouring it. The study of the four Majorcan cultivars possessing this allele has confirmed their selfincompatibility, showing that this allele is in its phenotypically active form, as it has been also observed in a group of cultivars from southern Italy, a fact possibly suggesting a connexion between these two Mediterranean almond populations.