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The ryegrass ( Lolium) species, perennial ryegrass ( Lolium perenne L.) and Italian ryegrass ( Lolium multiflorum Lam.), are the two most important pasture grass species for global temperate regions and are also useful for amenity purposes. Due to an outbreeding reproductive habit, high levels of genetic heterogeneity are present within cultivated varieties. A continual increase in delivery of new cultivars to the marketplace, along with limited capacity to discriminate on the basis of morphological characteristics in a grow-out test, has caused difficulties for distinctness, uniformity and stability ( DUS) testing in the current plant variety protection ( PVP) system. A range of genomic tools and resources have been generated for ryegrasses, which provide new opportunities and challenges to the current PVP system. In this review, the currently available genomic tools and resources are described, along with prospects for applications to the PVP system and testing for seed certification and purity accreditation. [ABSTRACT FROM AUTHOR]

Genomic selection ( GS) is a powerful method for exploitation of DNA sequence polymorphisms in breeding improvement, through the prediction of breeding values based on all markers distributed genome-wide. Forage grasses and legumes provide important targets for GS implementation, as many key traits are difficult or expensive to assess, and are measured late in the breeding cycle. Generic attributes of forage breeding programmes are described, along with status of genomic resources for a representative species group (ryegrasses). Two schemes for implementing GS in ryegrass breeding are described. The first requires relatively little modification of current schemes, but could lead to significant reductions in operating cost. The second scheme would allow two rounds of selection for key agronomic traits within a time period previously required for a single round, potentially leading to doubling of genetic gain rate, but requires a purpose-designed reference population. In both schemes, the limited extent of linkage disequilibrium ( LD), which is the major challenge for GS implementation in ryegrass breeding, is addressed. The strategies also incorporate recent advances in DNA sequencing technology to minimize costs. [ABSTRACT FROM AUTHOR]