Linkage drag analysis in three Aegilops speltoides introgressions carrying Sr47 in modern durum and hard red spring wheat germplasm

Authors: Klindworth, Daryl; SALSMAN, EVAN - North Dakota State University; UNDERDAHL, JESSE - North Dakota State University; ELIAS, ELIAS - North Dakota State University; GREEN, ANDREW - North Dakota State University; Dykes, Linda; Faris, Justin; Xu, Steven

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2023
Publication Date: 7/6/2023
Citation: Klindworth, D.L., Salsman, E., Underdahl, J., Elias, E.M., Green, A.J., Dykes, L., Faris, J.D., Xu, S.S. 2023. Linkage drag analysis in three Aegilops speltoides introgressions carrying Sr47 in modern durum and hard red spring wheat germplasm. Theoretical and Applied Genetics. 136. Article 168. https://doi.org/10.1007/s00122-023-04409-8.
DOI: https://doi.org/10.1007/s00122-023-04409-8

Interpretive Summary: Linkage drag refers to undesirable effects, potentially by many traits, of genes that are closely linked to a desired gene. If linkage drag is severe, it may block the usage of the desirable gene. We previously transferred the stem rust resistance gene Sr47 from a wild relative species of wheat into three durum wheat introgression lines, RWG35, RWG36, and RWG37. In this study, we developed 18 new durum and bread wheat lines by transferring Sr47 from RWG35, RWG36, and RWG37 into three modern durum and three modern bread wheat cultivars. These new lines were then tested for grain yield and end-use quality traits to determine the levels of linkage drag. The test results showed that the lines derived from RWG35 had little or no linkage drag, whereas the lines from RWG36 and RWG37 retained linkage drag. Therefore, breeders who wish to incorporate Sr47 into their cultivars should exclusively utilize the germplasm derived from RWG35. The new durum and bread wheat lines carrying Sr47 derived from RWG35 in the backgrounds of modern cultivars developed in this study will be the useful germplasm for durum and bread wheat breeding programs.

Technical Abstract: Three durum wheat (Triticum turgidum L., subsp. durum) lines, RWG35, RWG36, and RWG37 carrying slightly different Aegilops speltoides introgressions, but each carrying Sr47, were backcrossed to three durum and three hard red spring (HRS) wheat (Triticum aestivum, L.) cultivars to produce 18 backcross populations. Each population was backcrossed to the recurrent parent six times and prepared for yield trials to test for linkage drag. Lines carrying the introgression (S-lines) were compared to euploid sibling lines (W-lines) and their parents. Yield trials were conducted from 2018 to 2021 at three locations. Three agronomic and several quality traits were studied. In durum, lines derived from RWG35 had little or no linkage drag. Lines derived from RWG36 and RWG37 still retained linkage drag, most notably involving yield and thousand kernel weight, but also test weight, falling number, kernel hardness index, semolina extract, semolina protein content, semolina brightness, and peak height. In HRS wheat, the results were more complex, though the general result of RWG35 lines having little or no linkage drag and RWG36 and RWG37 lines retaining linkage drag still applied. But, there was heterogeneity in the Glenn35S lines, and Linkert lines had problems combining with the Ae. speltoides introgressions. We concluded that introgressions derived from RWG35 either had eliminated linkage drag or any negative effects were minor in nature. We recommend that breeders who wish to incorporate Sr47 into their cultivars should work exclusively with germplasm derived from RWG35.