Population Genetics of the Grass Self-incompatibility System—Practical Implications for Grass Breeding Programmes

Chloe Manzanares, Bruno Studer, Richard Charles Hayes, Susanne Barth, Danny Thorogood

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Citation (SciVal)


Self-incompatibility (SI) is a mechanism that prevents plants from self-pollination through molecular recognition between pollen and pistil; but neither the genes nor the proteins involved are known. Determining haplotype diversity of the SI locus region is an indirect way of predicting incompatibility genotype which would enable plant breeders to develop strategies to ensure precision crossing for exploiting heterotic combinations. In the case of ryegrass (Lolium perenne), SI is known to be a gametophytic reaction involving two loci, S and Z. This paper reports on an assay of marker allele diversity around the Z locus for a population produced from twelve generations of mixed and half-sib family selection. Using conventional genotyping of marker length polymorphisms, as well as high resolution melt (HRM) curve analysis, the 55 plants of the population were classified into thirteen groups according to their genotypes for each marker. HRM genotyping proved to be more discriminating than STS markers and could enhance the precision of Z genotype prediction. Although half-sib family selection is expected to lead to allele fixing, this initial analysis was encouraging in that it indicated high haplotype diversity around the Z-locus suggesting maintenance of a high degree of cross-compatibility in the breeding population. This would be expected as SI alleles are subjected to frequency dependent selection.
Original languageEnglish
Title of host publicationBreeding strategies for sustainable forage and turf grass improvement
EditorsSusanne Barth, Dan Milbourne
Place of PublicationDordrecht
PublisherSpringer Nature
ISBN (Electronic)978-9400745551
ISBN (Print)978-9400745544
Publication statusPublished - 01 Jan 2013


  • Haplotype diversity
  • High resolution melting
  • Frequency dependent selection
  • Plant breeding
  • Lolium perenne


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