Genotyping apricot cultivars for self-(in)compatibility by means of RNases associated with S alleles

In previous work the existence of proteins with RNase activity associated with S alleles in apricot was demonstrated. These proteins were inherited as described previously for the inheritance of self-compatibility in this species. In this study, new cultivars have been genotyped for self-compatibility using this method and it has been demonstrated that in all self-compatible cultivars examined, the self-compatibility allele is the same and is associated with an RNase with high activity. Homozygous self-compatible individuals have been detected among established cultivars as well as among seedlings following breeding activity. This germplasm is of great value within the breeding programme because only self-compatible seedlings will be produced. The number of S alleles in apricot appears to be low and only eight different alleles have been found in the large number of different cultivars screened. Furthermore, there are alleles present in the Spanish population that are also found in the genetic pool of NorthAmerican cultivars. The screening of a progeny from the cross between the American cultivar 'Goldrich' and the Spanish cultivar 'Pepito' demonstrated the existence of the common allele S (2) (detected previously by examining RNases), which was confirmed by the segregation of self-compatibility in the progeny.