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ARS Home » Pacific West Area » Pullman, Washington » Plant Germplasm Introduction and Testing Research » Research » Publications at this Location » Publication #410522
Research Project: Genetic Resource and Information Management for Pulse, Temperate Forage Legume, Oilseed, Vegetable, Grasses, Sugar, Ornamental, and Other Crops

Location: Plant Germplasm Introduction and Testing Research

Title: Genetic diversity, population structure and taxonomic confirmation in annual medic (Medicago spp.) collections from Crimea, Ukraine

Author
item ZHAO, DONYANG - Breeding Insight
item SAPKOTA, MANOJ - Breeding Insight
item LIN, MENG - Breeding Insight
item BEIL, CRAIG - Breeding Insight
item SHEEHAN, MOIRA - Breeding Insight
item GREENE, STEPHANIE - Retired ARS Employee
item Irish, Brian

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2024
Publication Date: 4/3/2024
Citation: Zhao, D., Sapkota, M., Lin, M., Beil, C., Sheehan, M., Greene, S., Irish, B.M. 2024. Genetic diversity, population structure and taxonomic confirmation in annual medic (Medicago spp.) collections from Crimea, Ukraine. Frontiers in Plant Science. 15:1339298. https://doi.org/10.3389/fpls.2024.1339298.
DOI: https://doi.org/10.3389/fpls.2024.1339298

Interpretive Summary: Globally important temperate-adapted forage legume collections in the USDA ARS National Plant Germplasm System include crops like alfalfa, annual medic species and many wild relatives. Character trait evaluations and a complementary molecular marker approach were used to accurate identity and estimate genetic diversity in annual medic germplasm collections originating from Crimea, Ukraine. The observable character traits were useful in grouping germplasm into clearly defined species. The molecular approach tested the utility of a newly developed alfalfa marker panel in assessing genetic diversity in related annual medics. The marker panel was also able to assign germplasm to species groups, to detect some mislabeled accessions and to identify diversity in the populations originating from Crimea. The unique germplasm accessions from Crimean have been incorporated into the permanent collections. In addition, research showed the efficacy of the marker panel which could be used for characterizing other larger plant genetic resource collections of related Medicago.

Technical Abstract: An annual medic (Medicago spp.) germplasm was collected from the Crimean Peninsula of Ukraine in 2008 to fill gaps in geographic coverage in the USDA ARS National Plant Germplasm System (NPGS) temperate-adapted forage legume collection. A total of 102 accessions across 10 Medicago species were collected. To assess genetic diversity, population structure, and to confirm taxonomic identities, the collections were phenotypically and genetically characterized. Phenotyping included the use of 24 descriptor traits while genetic characterization was accomplished using a 3K Diversity Array Technologies (DArTag) panel developed for alfalfa (Medicago sativa L.). For both field and molecular characterizations, a reference set of 92 geographically diverse and species-representative accessions were obtained from the NPGS collection. Phenotypic descriptors showed consistency among replicated plants within accessions, some variation across accessions within species, and evident distinctions between species. Because the DArTag panel was developed for cultivated alfalfa, the transferability of markers to the species being evaluated was limited, resulting in an average of ~1,500 marker loci detected per species. From these loci, 448 markers were present in 95% of the samples. Principal component and phylogenetic analysis based on a larger set of 2,396 selected markers clustered accessions by species and predicted evolutionary relationships among species. Additionally, the markers aided in the taxonomic identity of a few accessions that were likely mislabeled. The genotyping results also showed that sampling individual plants for these mostly self-pollinating species is sufficient due to high reproducibility between single (n=3) and pooled (n=7) biological replicate leaf samples. The phenotyping and the 2,396 SNP marker set were useful in estimating population structure in the Crimean and reference accessions, highlighting novel and unique genetic diversity captured in the Crimean accessions. Furthermore, this research showed that the DArTag marker panel and its corresponding SNP markers could be used in a similar fashion to evaluate other plant genetic resource collections of related Medicago.