Identification of genetic basis of agronomic traits in alfalfa (Medicago sativa subsp. sativa) using Genome Wide Association Studies

Alfalfa (Medicago sativa L.) is one of the most widely cultivated forage crops due to its high yield, value of nutrients, and adaptation to diverse environments. However, many of the desired agronomic traits in alfalfa are quantitative, and therefore improving them under abiotic and biotic stresses becomes an important goal in alfalfa breeding. One way to achieve such a goal is identification of loci that contribute to variation in complex traits. Genome Wide Association Studies (GWAS) provide advanced tools to identify genetic loci associated with traits of interest using high-density markers throughout the genome. In M. sativa, previous studies indicated that GWAS could identify numerous candidate single nucleotide polymorphism (SNP) markers for quantitative traits, including biomass, yield, forage quality, and drought/salt tolerance. Furthermore, mapping SNP markers against the M. sativa reference genome revealed many putative candidate genes which are associated with several cell wall-related traits. In this review, we summarize Genome Wide Association (GWAS) in alfalfa from concept to application and the identification and characterization of candidate genes for traits of interest.