Location: Cereal Crops ResearchTitle: A novel adult plant leaf rust resistance gene Lr2K38 mapped on wheat chromosome 1AL
|SAPKOTA, SURAJ - University Of Georgia|
|MERGOUM, MOHAMED - University Of Georgia|
|KUMAR, AJAY - North Dakota State University|
|JOHNSON, JERRY - University Of Georgia|
|BLAND, DAN - University Of Georgia|
|LOPEZ, BENJAMIN - University Of Georgia|
|SUTTON, STEVE - University Of Georgia|
|GHIMIRE, BIKASH - University Of Georgia|
|BUCK, JAMES - University Of Georgia|
|CHEN, ZHENBANG - University Of Georgia|
|HARRISON, STEPHEN - Louisana State University|
Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2020
Publication Date: 11/20/2020
Citation: Sapkota, S., Mergoum, M., Kumar, A., Fiedler, J.D., Johnson, J., Bland, D., Lopez, B., Sutton, S., Ghimire, B., Buck, J., Chen, Z., Harrison, S. 2020. A novel adult plant leaf rust resistance gene Lr2K38 mapped on wheat chromosome 1AL. The Plant Genome. 13:e20061. https://doi.org/10.1002/tpg2.20061.
Interpretive Summary: Wheat leaf rust is an important disease of wheat with the potential to cause significant yield losses worldwide. The use of resistant cultivars is a cost-effective way to mitigate this disease and the identification of new genetic resistance genes is critical as the pathogen can quickly adapt to overcome currently-used genetic sources. A soft red winter wheat line, AGS 2038, has a high level of adult plant resistance to this disease. In this study, we used a single mapping population with this line as a parent to identify specific genomic regions that confer adult and seedling resistance to leaf rust. Five resistance regions were discovered, and a single major one was found to be novel. This information is important for researchers investigating adult plant resistance mechanisms and breeders to aid in developing new wheat lines with durable leaf rust resistance.
Technical Abstract: Soft red winter wheat (SRWW) cultivar AGS 2038 has a high level of adult plant leaf rust (LR) resistance. To map and characterize LR resistance in AGS 2038, a recombinant inbred line (RIL) population consisting of 225 lines was developed from a cross between AGS 2038 and susceptible line UGA 111729. The parents and RIL population were phenotyped for LR response in three field environments at Plains and Griffin, GA, in the 2017-18 and 2018-19 growing seasons, and one greenhouse environment at the adult-plant stage. The RIL population was genotyped with Illumina 90K SNP iSelect marker array, and a total of 7667 polymorphic markers representing 1513 unique loci were used to construct a linkage map. Quantitative trait loci (QTL) analysis detected a total of five QTL, QLr.ags-1AL, QLr.ags-2AS, QLr.ags-2BS1, QLr.ags-2BS2, and QLr.ags-2DS, for adult plant LR resistance. Of these, a major QTL, QLr.ags-1AL, was detected on all tested environments and explained up to 34.45% of the phenotypic variation. QLr.ags-1AL, tightly flanked by IWB20487 and IWA4022 markers, was contributed by AGS 2038. Molecular marker analysis using a diagnostic marker linked to Lr59 showed that QLr.ags-1AL was different from Lr59, the only known LR resistance gene on 1AL – therefore, the QTL was temporarily designated as Lr2K38. Lr2K38 linked marker IWB20487 was highly polymorphic among SRWW lines and should be useful for deploying the Lr2K38 gene in wheat breeding programs.