Genetic characterization and genome-wide association mapping for dwarf bunt resistance in bread wheat accessions from the USDA National Small Grains Collection

Authors: Gordon, Tyler; WANG, RUI - University Of Idaho; HOLE, DAVID - Utah State University; Bockelman, Harold; Bonman, John; CHEN, JIANLI - University Of Idaho

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2020
Publication Date: 1/14/2020
Citation: Gordon, T.C., Wang, R., Hole, D., Bockelman, H.E., Bonman, J.M., Chen, J. 2020. Genetic characterization and genome-wide association mapping for dwarf bunt resistance in bread wheat accessions from the USDA National Small Grains Collection. Journal of Theoretical and Applied Genetics. 133:1069-1080. https://doi.org/10.1007/s00122-020-03532-0.
DOI: https://doi.org/10.1007/s00122-020-03532-0

Interpretive Summary: Dwarf bunt (DB) is a fungal disease that causes significant yield and quality losses in bread wheat. Genetic resistance to DB offers a cost-effective method of controlling DB in bread wheat production systems. We selected 136 resistant accessions from the National Small Grains Collection and paired these resistant accessions with 136 susceptible accessions and 16 bunt differentials to form a genome-wide association study (GWAS) panel. We tested the accessions in the GWAS panel with replicated field trials in a DB nursery in 2017 and 2018. The field data was used to identify accessions that were resistant to DB, and genetic information from the GWAS was used to locate chromosomal regions and molecular markers associated with resistance. Resistant accessions and molecular markers identified in this study can be used to introduce DB resistance into adapted bread wheat cultivars.

Technical Abstract: Dwarf bunt (DB), caused by Tilletia controversa J.G. Kühn, can significantly reduce grain yield and quality on autumn-sown wheat in regions with prolonged snow cover. DB can be managed with the use of resistant cultivars. The objectives of the present study were to characterize DB resistance in a large set of bread wheat accessions from the National Small Grains Collection (NSGC) and use a genome-wide association study (GWAS) approach to identify quantitative trait loci (QTL) associated with DB resistance. A total of 292 accessions were identified using historical DB resistance data recorded across many trials and years in the Germplasm Resources Information Network (GRIN) and re-tested for DB resistance in replicated field nurseries in Logan, UT, in 2017 and 2018. One-hundred-nine accessions were resistant with DB normalized incidence =10% and thirty-five of these were highly resistant with DB normalized incidence =1% in both GRIN and the field nurseries. GWAS revealed fourteen quantitative trait loci (QTL) significantly (P <0.001) associated with DB resistance in at least two DB data sets. These QTL were on chromosomes 1A, 1D, 2B, 3B, 4A, 5B, 5D, 6D, and 7B, and explained 4-14% of the observed phenotypic variation. QTL on 1A, 1D, 2B, 5B and 7B were not reported previously and could be novel. Resistant accessions and molecular markers identified in the present study may provide a valuable resource for acquisition, deployment and characterization of DB resistance in bread wheat.