Identification of self-(in)compatibility alleles in apricot by PCR and sequence analysis

This report shows the PCR-based identification of the eight known self-(in)compatibility alleles (S1 to S7 and S(c)) of apricot (Prunus armeniaca L.). Two sets of consensus primers, designed from P. armeniaca S-RNase genomic sequences and sweet cherry (P. avium L.) S-RNase-cDNAs, were used to amplify fragments containing the first and the second S-RNase intron, respectively. When the results obtained from the two PCRs were combined, all S-alleles could be distinguished. The identity of the amplified S-alleles was verified by sequencing the first intron and 135 base pairs (bp) of the second exon. The deduced amino acid sequences of these fragments showed the presence of the C1 and C2 Prunus L. S-RNase conserved regions. These results allowed us to confirm S-genotypes previously assigned by stylar ribonuclease analyses and to propose one self-(in)compatibility group (I) and one universal donor group (O) containing unique S-genotypes and self-compatible cultivars (SC). This PCR-based typing system also facilitates the identification of the S(c)-allele and might be a very useful tool for predicting self-compatibility in apricot breeding progenies.