Molecular markers for high-throughput detection of a self-fertility (Sf) allele in almond
The gametophytic self-incompatibility (SI) system of almond (Prunus dulcis) is genetically controlled by a complex S locus with many alleles for self-incompatibility and at least one allele (Sf) for self-fertility. In almond breeding, it is useful to have molecular markers that can differentiate the Sf allele from SI alleles. Until now, the markers developed for this purpose have relied on gel electrophoresis to detect sequence polymorphisms within introns of the S-RNase gene in the S locus. With these markers, the amplicons for some SI alleles are indistinguishable from those for the Sf allele. In this study, a series of fluorescence-based markers was designed to assay polymorphisms in an otherwise conserved region (C2) of the S-RNase gene. With the application of these markers to clones with known S genotypes and to 16 breeding populations, it was demonstrated that each of these markers can reliably distinguish self-fertile genotypes from self-incompatible genotypes. In some cases, it was also possible to distinguish among different self-fertile genotypes (heterozygous combinations of Sf with different SI alleles). Phenotypic evaluation of selected progeny from six populations confirmed the accuracy of the genotypic results. These markers provide powerful tools to detect the Sf allele in almond and could serve as models for the development of high-throughput markers for other crops with self-incompatibility systems.
Goonetilleke, S.N.S., Croxford, A.E., Wirthensohn, M.G., March, T.J. and Mather, D.E. (2019). Molecular markers for high-throughput detection of a self-fertility (Sf) allele in almond. Acta Hortic. 1231, 143-150
S locus, S-RNase gene, SI alleles, conserved region, marker assays, genotypes