Mapping and validation of stem rust resistance loci in spring wheat line CI 14275

Authors: KOSGEY, ZENNAH - Kenya Agricultural And Livestock Research Organization; EDAE, ERENA - University Of Minnesota; DILL-MACKY, RUTH - University Of Minnesota; Jin, Yue; BULBULA, WORKU - Ethiopian Institute Of Agricultural Research; GEMECHU, ASHENAFI - Ethiopian Institute Of Agricultural Research; GODWIN, MACHARIA - Kenya Agricultural And Livestock Research Organization; BHAVANI, SRIDHAR - International Maize & Wheat Improvement Center (CIMMYT); RANDHAWA, MANDEEP - International Maize & Wheat Improvement Center (CIMMYT); Rouse, Matthew

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2020
Publication Date: 1/12/2021
Citation: Kosgey, Z.C., Edae, E.A., Dill-Macky, R., Jin, Y., Bulbula, W.D., Gemechu, A., Godwin, M., Bhavani, S., Randhawa, M.S., Rouse, M.N. 2021. Mapping and validation of stem rust resistance loci in spring wheat line CI 14275. Frontiers in Plant Science. 11. Article e609659. https://doi.org/10.3389/fpls.2020.609659.
DOI: https://doi.org/10.3389/fpls.2020.609659

Interpretive Summary: Stem rust is a devastating disease of wheat. Wheat stem rust resistance genes can be used to control stem rust. In this study, we characterized the genetics of stem rust resistance, identified QTLs and described markers associated with stem rust resistance in spring wheat line CI 14275. Screening for resistance to Pgt races in the field was undertaken in Kenya, Ethiopia, and the United States in 2016, 2017, and 2018. Four and three quantitative trait loci (QTL) were identified that conferred field and seedling resistance, respectively. A QTL on chromosome 2B conferred resistance in Kenya and Ethiopia, was validated in a second population, and a molecular marker was shown to have potential to select for this QTL in marker assisted selection. This is the first study to both detect and validate an adult plant stem rust resistance QTL on chromosome arm 2BS. The combination of three field QTL consistently reduced stem rust disease in Africa and the United States. The gene combination present in CI 14275 could potentially be transferred or selected in other wheat lines to be used to develop durable stem rust resistance in new wheat varieties.

Technical Abstract: Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) remains a threat to wheat production in East African wheat growing regions. In this study, we characterized the genetics of stem rust resistance, identified QTLs and described markers associated with stem rust resistance in spring wheat line CI 14275. The 113 recombinant inbred lines together with their parents were evaluated at the seedling stage against Pgt races TTKSK, TRTTF, TPMKC, TTTTF, and RTQQC. Screening for resistance to Pgt races in the field was undertaken in Kenya, Ethiopia, and the United States in 2016, 2017, and 2018. One and three complementary genes conferred seedling resistance to races TTTTF and RTQQC, respectively. Four and three QTL were identified that conferred field and seedling resistance, respectively. QTL QSr.cdl-2BS.2, that conferred resistance in Kenya and Ethiopia was validated and the marker Excalibur_c7963_1722 was shown to have potential to select for this QTL in marker assisted selection. The QSr.cdl-3B.2 is likely Sr12, QSr.cdl-4AL.1 is postulated as Sr7a, QSr.cdl-6BL.1 is likely Sr11, and QSr.cdl-6AS.1 appears to be a new QTL. This is the first study to both detect and validate adult plant stem rust resistance QTL on chromosome arm 2BS. The combination of field QTL QSr.cdl-2BS.2, QSr.cdl-3B.2, and QSr.cdl-6AS.1 has the potential to be used in breeding to reduce stem rust severity in Africa.