Haploid and Doubled Haploid Techniques in Perennial Ryegrass (Lolium perenne L.) to Advance Research and Breeding

The importance of haploid and doubled haploid (DH) techniques for basic and applied research, as well as to improve the speed of genetic gain when applied in breeding programs, cannot be overstated. They have become routine tools in several major crop species, such as maize (Zea mays L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). DH techniques in perennial ryegrass (Lolium perenne L.), an important forage species, have advanced to a sufficiently successful and promising stage to merit an exploration of what their further developments may bring. The exploitation of both in vitro and in vivo haploid and DH methods to (1) purge deleterious alleles from germplasm intended for breeding; (2) develop mapping populations for genetic and genomic studies; (3) simplify haplotype mapping; (4) fix transgenes and mutations for functional gene validation and molecular breeding; and (5) hybrid cultivar development are discussed. Even with the comparatively modest budgets of those active in forage crop improvement, haploid and DH techniques can be developed into powerful tools to achieve the acceleration of the speed of genetic gain needed to meet future agricultural demands.