Contribution of Western and Eastern species to the Iranian pear germplasm revealed by the characterization of S-genotypes.

Iran is recognized as an important source of genetic diversity of pear germplasm including native and introduced species. It is located in the Mid-Asian, center of diversification of the genus Pyrus, where several species have originated; moreover, the Silk Road historically favoured an intense exchange of cultivated crops and agricultural technologies during the course of trade and cultural transmission between ancient China and central/West Asia. Thus, Iran is maybe one of the first places where specimens of Pyrus communis imported from Europe could have come into contact with Pyrus pyrifolia, syn. P. serotina genotypes coming from eastern Asian countries. Moreover, pear species exhibit the S-RNase-based gametophytic self-incompatibility system that prevents self-fertilization thus forcing out-crossing. Since there is no major barrier for hybridization in Pyrus, several different species might have contributed to the makeup of the Iranian traditional germplasm. The characterization of self-incompatibility ribonucleases in Iranian P. communis cultivars and landrace genotypes revealed that, in addition to the pool of alleles previously detected in European cultivars, the Iranian germplasm shows the presence of alleles most likely introduced via hybridization with cultivated or wild Pyrus species.