Germplasm Collection, Genetic Resources, and Gene Pools in Alfalfa

Abstract

AbstractPopular for its feed quality and benefits to the environment, alfalfa (Medica sativa L.) is the most economically important forage legume crop in the world. Most agricultural crops have plant genetic resource (PGR) collections that are conserved, with their use promoted by national and international genebanks. Large alfalfa germplasm collections are held, in the form of seed, in genebanks worldwide. These same genebanks also are responsible for many other cultivated species and alfalfa crop wild relatives (CWR) in the genus Medicago. Once acquired, these taxonomically diverse collections are actively managed, requiring ideal storage to promote longevity, regeneration activities to resupply viable seed, and sample duplicates to safeguard against loss. Extensible database software platforms continue to expand capabilities for maintaining fidelity and public access to accession-associated information. As resources and policies allow, PGR are distributed to stakeholders (e.g., plant breeders) in public, non-profit, and private research sectors. Many of the PGR have been extensively characterized and evaluated for important phenotypic, agronomic, and genetic traits. As many of the alfalfa and other Medicago spp. collections are too large to evaluate at once, subsets of representative genetically distinct accessions (i.e., core collections) have been established and evaluated. Data generated in characterizations and evaluations are often linked to accessions and continue to expand, helping users identify useful germplasm. Although difficult to assess because alfalfa and many Medicago spp. accessions are often heterozygous outcrossing polypoid populations, comprehensive genetic diversity has been described for some of the larger collections. Diversity and accession numbers for CWR collection holdings are much lower, although the potential value in introgressing key traits from germplasm in these genepools has been shown. In the United States, early plant germplasm introductions played important roles in breeding modern alfalfa cultivars. Many of these traits (e.g., cold adaptation and biotic/abiotic resistance) have contributed to expanded growing areas and sustainable production. Historically, the production of alfalfa and other Medicago spp. forages has benefited from the diversity conserved in PGR collections. Continued access to these critical Medicago spp., PGR will only be secure if committed support from stakeholder communities endures.Keywords Medicago Genetic resourcesGermplasmForagesLegumeDiversity