Unravelling Self-incompatibility for Efficient Forage and Turf Grass Breeding

Perennial ryegrass is one of the most important grassland species of temperate regions worldwide. It exhibits a gametophytic self-incompatibility (SI) system which is controlled by two independent loci, S and Z. Therefore, perennial ryegrass has - so far - been improved as open pollinated populations or synthetic varieties.

We have used a map-based cloning strategy in order to identify the S and Z SI region in perennial ryegrass. By a comparative genetic approach, bacterial artificial chromosome (BAC) clones covering the genomic region co-segregating for both the S and Z loci were isolated. A pooled BAC clone sequencing strategy was used to establish physical contigs for both regions. Assembled and annotated physical contigs provided the basis for the development of molecular markers predictive for haplotypes and SI alleles. Armed with such a diagnostic tool we can begin to consider how to utilize SI for pollination control in breeding schemes that aim to maximize the genetically available heterosis.

Here, we briefly report about a fine-mapping strategy to isolate the S and Z SI loci in perennial ryegrass which allowed the development of DNA markers predictive for SI alleles. However, the main focus of the presentation will be about implications of this novel breeding tool to control pollination for future forage and turf grass breeding.