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ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #435461
Research Project: Maintenance, Characterization, Evaluation, and Enhancement of Genetic Resources in the National Soybean Germplasm Collection

Location: Soybean/maize Germplasm, Pathology, and Genetics Research

Title: Harnessing genomic diversity: from wild relatives to elite alfalfa cultivars

Author
item MEDINA, CESAR - University Of Minnesota
item Xu, Zhanyou

Submitted to: Book / Chapter / eBook
Publication Type: Book / Chapter
Publication Acceptance Date: 8/3/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: N/A

Technical Abstract: Cultivated alfalfa (Medicago sativa L.) is the most vital forage legume globally, recognized for its high nutritional value, exceptional biomass productivity, and critical ecosystem services. However, genetic gains in alfalfa biomass yield have remained stagnant in North America for decades. This stagnation is primarily driven by prolonged selection cycles, the biological complexities of breeding an autotetraploid, obligate outcrossing species, and a narrow commercial genetic base. This chapter evaluates and synthesizes a comprehensive, multi-year effort that merges two major initiatives aimed at expanding genetic diversity in alfalfa breeding: a large-scale genebank accession diversity project (PI2022) and a targeted pre-breeding project (WARP21). The long-term objective is to unlock and exploit the genetic diversity conserved within global genebanks. By screening 1,986 genotypes from the U.S. National Plant Germplasm System (NPGS) (50.9%) alongside regionally adapted Eurasian pre-breeding populations (49.1%), this research covers the full evolutionary spectrum of alfalfa from crop wild relatives to elite cultivars. The deployment of innovative 3K DArTag microhaplotype markers enabled the integration of these two projects, the redefinition of population clusters, and the genetic diversity. We document how these molecular markers facilitated the reclassification of several accessions, thereby refining taxonomic boundaries within the Medicago sativa complex. Finally, we outline selection frameworks designed to mitigate genetic erosion during long-term selection cycles. Ultimately, this work establishes a strategic genomic and phenotypic roadmap to break the yield plateau and secure long-term climate resilience in alfalfa production.