Population Genomics of Perennial Temperate Forage Legumes

Temperate forage legumes are essential components of agricultural systems around the globe with a notable economic value. Being perennials with developed root systems, forage legumes mitigate a number of foremost problems of contemporary agricultural practices including erosion and nutrient leaching. As forage legumes host rhizobium in their roots through symbiotic relationship, they fix a significant amount of atmospheric nitrogen to soil reducing the dependency on synthetic fertilizers, and thus, ensuring the sustainability of the agricultural systems. Despite their widespread cultivation and high ecological and economic value, the genomics studies in forage legumes have lagged behind other crops or domesticated animals. Owing to the recent advances of high-throughput sequencing technologies that accompanied by advanced bioinformatics tools, thousands to millions of single nucleotide polymorphisms (SNP) are easily identified and employed in virtually any crop including low-resource forage legumes. Development of these and other genomics resources, approaches, and tools has allowed to address the key questions in the population genomics of perennial temperate forage that includes examining genetic diversity and population structure of cultivated and wild populations, origin and genetic relationships among species, identification of the center of origin, understanding domestication patterns, unveiling the pattern of acclimation and adaptation to climate change, and investigating the effective use of the genomics tools such as GWAS and genome-wide selection. In the present chapter, key population genomics aspects of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), white clover (Trifolium repens L.), sainfoin (Onobrychis viciifolia Scop.), and birdsfoot trefoil (Lotus corniculatus L.) are synthesized and discussed. Then future perspectives of population genomics research and applications in temperate forage legumes are discussed.