Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/7/2021
Publication Date: 7/18/2021
Citation: Yu, L., Medina, C., Peel, M. 2021. Genetic and genomic assessments for improving drought resilience in alfalfa. In: Yu LX., Kole C., editors. The Alfalfa Genome. Compendium of Plant Genomes. Springer. Cham, Switzerland. p.235-253. https://doi.org/10.1007/978-3-030-74466-3_14.
Interpretive Summary: Alfalfa is a major forage crop around the world and is the third most valuable field crop produced in the U.S. Abiotic stresses such as drought and high salinity affect alfalfa production resulting in severe economic losses. Genetic improvement in alfalfa has occurred at a slower pace than in other crops. Conventional breeding approaches have not exploited the full yield potential. The use of molecular tools such as marker-assisted selection (MAS) and genomics-assisted breeding (GAB) can accelerate the breeding process. In this chapter, we provide the background of traditional breeding for drought tolerance and review recent progress in utilization of genomic approaches toward improving drought resilience in alfalfa.
Technical Abstract: Alfalfa (Medicago sativa L.) production is challenged by adverse environmental factors. Developing alfalfa varieties with resistance to these stresses is imperative for sustainable alfalfa production worldwide. Abiotic stresses such as drought and high salinity affect alfalfa production resulting in severe economic losses. Conventional breeding procedures to develop alfalfa cultivars are time consuming and costly. The use of molecular tools such as marker-assisted selection and genomics-assisted breeding can accelerate the breeding process. Recent advances in next-generation sequencing have provided a new strategy to generate cost-effective, high-density, genome-wide single nucleotide polymorphisms (SNPs). In conjunction with genome-wide association studies (GWAS) and/or genomic selection (GS), more powerful platforms can be developed to improve gains in alfalfa breeding. Given that alfalfa cultivars are genetically broad-based synthetic populations, it has been a challenge understanding genetic mechanisms by which environmental factors affect alfalfa plant growth, development and production. Genomic approaches such as genotyping by sequencing (GBS), association mapping (AM), GAB and GS can be applied to overcome the bottleneck of traditional breeding. Studies have been performed in recent years describing the generation of large marker sets in alfalfa and performing GAB for enhanced drought resistance. In addition, transcriptomics and gene regulation network in response to drought stress have been investigated in alfalfa.