Identification and S-genotyping of Novel S-alleles in Wild Species of Pyrus Genus

The Pyrus species exhibit the gametophytic self -incompatibility which is considered to be the most widespread self-incompatibility system among flowering plants. This system prevents self-fertilization through a specific pollen-pistil recognition mechanism. The S-allele diversity in the Iranian genotypes indicates that the pear germplasm of Iran can be an excellent source of variability for breeding programs. In this study, the S-RNases of 64 pear cultivars and wild genotypes of Pyrus species of Iran and Europe including; Pyrus communis, Pyrus salicifolia, Pyrus syriaca and Pyrus ussuriensis were amplified using consensus and allele-specific primers by PCR-based method. This method was used for the detection of product size characteristics of the 23 S-RNases (S101-S125) and revealed the existence of one new allele named S127 and the footprint of S8 of P. pyrifolia syn. P. serotina in Iranian genotypes. Interestingly, in 6 specimens allele PcS127 is coupled with PpS8, suggesting that these plants might come from subgroups or populations where the contribution of P. Pyrifolia syn. P. serotina is more consistent. The pool of S-RNases found in the Iranian germplasm had a different composition from the European cultivars, and showed traces of significant genetic contribution from other species. Also, application of this approach in 21 European cultivars allowed re-evaluation of alleles of Veerdi (S101/S104) and Conseiller a la Coeur (S103/S123/S105).