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Background: Allelic diversity of the S-locus is attributed to the genetic relationships among genotypes and sexual reproduction strategy. In otherwise self-incompatible Prunus species, the emergence of loss-of-function in S-haplotypes has resulted in self-compatibility. This information may allow following major stages of crop history. The genetic diversity in the S-locus of local apricots (Prunus armeniaca L.) from different oasis ecosystems in Morocco and the comparison of the occurrence and frequency of S-alleles with other regions may allow testing the validity of previous theories on the origin and dissemination of North African apricots.

Results: The S-genotypes of 55 Moroccan apricot accessions were determined, resulting in 37 self-compatible genotypes, from which 33 were homozygotes for self-compatibility. S-C was the most frequent S-allele in this germplasm, followed by S-13, S-7, S-11, S-2, S-20, S-8, and S-6. New approaches (CAPS or allele-specific PCR) were designed for a reliable verification of the rare or unexpected alleles. The frequency and distribution of the S-alleles differed among the oases. Some of these alleles, S-8, S-11, S-13 and S-20, were formerly detected only in the Irano Caucasian germplasm and are not present in Europe.

Conclusions: Our data supports the Irano-Caucasian origin of the Moroccan apricots and their original introduction by Phoenicians and Arabs through the North African shore. North Africa seems to have preserved much higher variability of apricot as compared with Europe. The loss of genetic diversity in apricot might be explained by the occurrence of self-compatibility and the length of time that apricot has spent with this breeding system in an environment without its wild relatives, such as the Moroccan oases or Central Europe.