Pear fruit set was affected by several genetic and environmental factors such as incompatibility system. Self-incompatibility (SI) is controlled in the Rosaceae by a homomorphic, gametophytic, monofactorial, multiallelic incompatibility system and pollen rejection occurs in the style. The incompatibility locus controls self-incompatibility as well as intra-specific cross-incompatibility. The present research was carried out during 2004 growing season at Tarbiat Modarres University (TMU) Iran, in order to evaluate incompatibility system in five European pear (Pyrus communis L.) cultivars. Polymerase chain reaction (PCR) with specific primers was applied to investigate SI genes in pear cultivars including `Shah-Miveh’, `Spadona’, `Sard-rod’, `Mohammad-Ali’ and `Bartlet’. DNA was extracted according to the modified CTAB method and SI gene was amplified using specific primers. The results indicated that primers could amplify SI gene and S-locus was exist in the mentioned cultivars. The first pare primers showed that there was one pare of S1, S3-S7 alleles in `Shah-Miveh’ and `Mohammad-Ali’. The similar band pattern with S2 allele was observed in `Sard-Rod’ and `Bartlet’ cultivars. In addition, in `Spadona’, `Sard-Rod’ and `Bartlet’ a 1400 base pair band was amplified suggested the existence of new possible allele. Note that the similar results were observed using other primers. In conclusion, we suggest using suitable combination of cultivars with different S alleles for new established pear orchard and breeding programs.
