Identification and characterization of genomic DNA sequences of the S‐ribonuclease gene associated with self‐incompatibility allelesS1toS5in European pear

Abstract

AbstractThe stylar products of the S‐locus for the gametophytic self‐incompatibility (GSI) system in theRosaceaeare ribonucleases (S‐RNases). Recently, sequences for 13 pearS‐RNase alleles have been published and named following a letter–symbol nomenclature (SatoSdandShtoSp). To establish the correspondence between these sequences and the self‐incompatibility alleles we have described previously (S1toS5), we have amplified genomic DNA with consensus primers from the cultivars, ‘Williams’ (S1S2), ‘Coscia’ (S3S4), ‘Butirra Precoce Morettini’ (S1S3), ‘Santa Maria Morettini’ (S2S3) and ‘Doyenne du Comice’ (S4S5) and identified PCR products specifically associated with eachSallele. Cloning and sequencing of the amplification products has revealed that they correspond to European pear sequences already deposited in the database. This allowed us to linkS‐RNase sequences withSallele phenotypes and to determine a correspondence between the symbol–letter nomenclature used to nameS‐RNase sequences and the number‐based nomenclature used to nameSalleles. Based on this result the prediction of new cross‐incompatibilities among pear cultivars is discussed. Finally, we propose a unified number‐based nomenclature to avoid future confusion denominatingSalleles in pear.