|Bonman, John - Mike|
|Cuesta-marcos, Alfonso - Oregon State University|
|Esvelt Klos, Kathy|
|Chen, Jianli - University Of Idaho|
|Akhunov, Eduard - Kansas State University|
|Zhang, Junli - University Of California|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2015
Publication Date: 4/27/2015
Citation: Bonman, J.M., Babiker, E.M., Cuesta-Marcos, A., Esvelt Klos, K.L., Brown Guedira, G.L., Chao, S., See, D.R., Chen, J., Akhunov, E., Zhang, J., Bockelman, H.E., Gordon, T.C. 2015. Genetic diversity among wheat accessions from the USDA National Small Grains Collection. Crop Science. 55(3):1243-1253.
Interpretive Summary: Wheat maintained in the USDA-ARS National Small Grains Collection (NSGC) is a resource for plant breeders worldwide. A better understanding of the genetic diversity within the collection will enable scientists to maximize the value of the NSGC for research, and especially for studies related to wheat breeding. We used two types of molecular markers to measure genetic diversity within the NSGC bread wheat ‘core subset’. The subset represents 10% of the bread wheats in the collection and accessions for the subset were selected to represent all of the countries of origin among the NSGC wheats. The core subset includes a large number of ‘landraces’ or heirloom varieties from Iran that were contributed to the collection in 1997. Using the markers, we discovered that apparent duplication within the core subset was more frequent than previously thought. This realization provides new avenues for further study that could lead to more efficient means of managing the collection. Also, we concluded that the Iranian landraces, although relatively less diverse as a group, contributed genetic variability to that collection that was previously not well-represented, such as resistance to Russian wheat aphid and to bunt diseases. Finally, this study showed that establishing core subsets based on the geographic origin of accessions was a good way to capture genetic diversity.
Technical Abstract: Accessions of Triticum aestivum subsp. aestivum from the USDA-ARS National Small Grains Collection (NSGC) are a resource for wheat scientists worldwide. The genetic diversity of the wheat core subset, representing approximately 10% of the collection’s 42138 T. aestivum accessions, was examined using 390 Diversity Arrays Technology (DArT)® markers, 4941 SNPs, and descriptor data. The marker profiles revealed duplicates, which were excluded to form an informative core (iCore) of 3233 accessions. The iCore population structure and diversity within various subgroups were examined with analysis of molecular variance, principal coordinate analysis, cluster analysis, and by ranking the contribution of individual accessions to overall diversity. Accession groups based on molecular marker data corresponded well to their geographic origin, and population structure was accounted for primarily by differences between Iranian landrace accessions and the rest of the accessions. Accessions classified as breeding lines were overrepresented among those ranked as most diverse based on SNP data, whereas Iranian landraces were underrepresented. Although less diverse as a group, Iranian landrace accessions had a higher frequency of resistance to bunt diseases and Russian wheat aphid compared to the iCore as a whole. The present study provides support for establishing core subsets based on geographic origin of accessions and will be a basis for further study of diversity among NSGC wheats.