Identification of the S3 self-incompatibility allele in almond by specific primers

Abstract

To date, the identification of the S3 self-incompatibility allele in almond using PCR primers has been problematic, either because of its weak amplification in some allelic combinations, or because of a lack of polymorphism in comparison with the self-compatibility (Sf) allele. This paper describes the use of three new primers, one "forward" (S3F) and two "reverse" (S3R1 and S3R2), specifically designed to amplify the S3 allele. Primers S3F and S3R1 were designed from the sequence of the second intron of this allele, while S3R2 was designed from the sequence upstream of the RC4 conserved region. Four primer combinations (S3F/S3R2, S3F/ConR, ConF/S3R1 and ConF/S3R2) satisfactorily amplified the S3 allele. The use of consensus primers from the S-RNase intron sequences allows specific identification of the S-alleles, and indicates the expected size of the amplified fragment.