Renumbering the S-RNase alleles of European pears (Pyrus communis L.) and cloning the S109 RNase allele

In the last 5 years 18 S-RNase alleles have been cloned from European pear (Pyrus communis L.). The annotation of the S-RNase alleles that have been cloned from European pear (Pyrus communis L.) was not consistent, and they were named both by letters and by numbers. In addition crosses between European and Japanese pear (Pyrus pyrifolia Nakai) for breeding purposes created the need to distinguish clearly between the origins of the various S-RNases. In an attempt to end this confusion, a joint decision of the research groups that had cloned the European pear S-RNase alleles and had S-genotyped many of the cultivars, undertook to renumber the European pear S-RNase alleles. The new numeration starts from 101 where the first digit unequivocally identifies the S-RNase alleles as belonging to the European pear gene pool. Accordingly, the new S-genotype designations of 133 European pear cultivars are presented. In addition, a description of the 18th pear S-RNase allele, S109, is reported.