Stem rust resistance in North American spring wheat to Ug99 and other virulent pathotypes of Puccinia graminis f. sp. tritici
9 affiliations
- 1Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN 55108 USA
- 2Food Crops Research Center, Kenya Agricultural and Livestock Research Organization (KALRO), Njoro, Kenya
- 3Cereal Disease Lab, United States Department of Agriculture-Agricultural Research Service, St. Paul, MN 55108 USA
- 4Debre Zeit Agricultural Research Center, Ethiopian Institute of Agricultural Research, Bishoftu, Ethiopia
- 5International Maize and Wheat Improvement Center (CIMMYT), ICRAF Campus, United Nations Avenue, P.O. Box 1041-00621 Gigiri, Nairobi Kenya
- 6U.S. Dairy Forage Research Center, United States Department of Agriculture-Agricultural Research Service, Madison, WI 53706 USA
- 7United States Department of Agriculture-Agricultural Research Service, Sugarcane Field Station, Canal Point, FL 33438 USA
- 8Department of Plant Pathology, University of Florida, Gainesville, FL 32611 USA
- 9Department of Plant Pathology, University of Minnesota, Saint Paul, MN 55108 USA
Abstract
Key message: North American spring wheat shows limited seedling resistance to a diverse set of exotic Pgt races but harbors valuable field resistance, including a strong locus for field resistance on chromosome 7AL.
Abstract: The emergence and spread of Ug99 and other races of Puccinia graminis f. sp. tritici (Pgt) with virulence to widely deployed resistance genes threaten global wheat production. This study evaluated North American spring wheat germplasm for seedling responses to four Pgt races (TTKSK, TTKSF+, TKTTF, and TRTTF) and for field response across five environments in Ethiopia and Kenya. Seedling evaluation revealed significant race-specific variation, with 82% of the lines exhibiting resistance to race TKTTF but very limited resistance to the other races. Gene postulation based on resistance patterns suggested a high frequency of Sr7a (~ 92%) in this panel, with only a few lines (~ 5%) carrying Sr8a, Sr11, and/or Sr31. Field evaluations in Ethiopia and Kenya demonstrated quantitative variation for field response, with several lines showing consistent field resistance. Association mapping identified 37 significant associations for seedling resistance, representing 17 unique genomic regions. For field response, 15 significant associations were detected, including a region on chromosome arm 7AL that was consistently detected across environments. Further analysis indicated that this locus confers adult-plant resistance (APR) and might be independent of known stem rust resistance genes located in the region. Hence, KASP assay was developed to enable marker-assisted selection and further investigation of this locus. This study highlights limited seedling resistance but identifies promising sources of field resistance against exotic Pgt races and provides valuable insights into the genetics underlying both seedling and field responses in North American germplasm.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00122-026-05352-0.
Related
- Spatial dynamics of systemic acquired resistance-associated metabolites in the wheat cultivar fielder infected by Blumeria graminis f. sp. tritici
- Discovery of a Virulent Population of Meloidogyne graminicola Overcoming the Rice Resistance Gene MG1 and Population Genetic Analysis Based on mtCOI Sequences
- Mapping, stacking and characterization of a novel resistance haplotype against GpaVvrn-virulent Globodera pallida derived from wild potato relative Solanum brevicaule
- Resistance mutation supply modulates the benefit of CRISPR immunity against virulent phages in Pseudomonas aeruginosa
- PtRTP1, an Effector of Puccinia triticina, Contributes to Virulence in Wheat
BibTeX
@article{gill2026stem,
title = {{Stem rust resistance in North American spring wheat to Ug99 and other virulent pathotypes of Puccinia graminis f. sp. tritici}},
author = {Harsimardeep S. Gill and Emily Conley and Kimani Cyrus Ndung’u and Pablo Olivera Firpo and Charlotte Brault and Zennah Kosgey and Ashenafi Gemechu Degete and Sridhar Bhavani and Prabin Bajgain and Matthew N. Rouse and Yue Jin and James A. Anderson},
journal = {TAG. Theoretical and Applied Genetics. Theoretische Und Angewandte Genetik},
year = {2026},
month = oct,
doi = {10.1007/s00122-026-05352-0},
url = {https://doi.org/10.1007/s00122-026-05352-0},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Stem rust resistance in North American spring wheat to Ug99 and other virulent pathotypes of Puccinia graminis f. sp. tritici
AU - Harsimardeep S. Gill
AU - Emily Conley
AU - Kimani Cyrus Ndung’u
AU - Pablo Olivera Firpo
AU - Charlotte Brault
AU - Zennah Kosgey
AU - Ashenafi Gemechu Degete
AU - Sridhar Bhavani
AU - Prabin Bajgain
AU - Matthew N. Rouse
AU - Yue Jin
AU - James A. Anderson
PY - 2026
DA - 2026/10/27
JO - TAG. Theoretical and Applied Genetics. Theoretische Und Angewandte Genetik
DO - 10.1007/s00122-026-05352-0
UR - https://doi.org/10.1007/s00122-026-05352-0
AB - Key message: North American spring wheat shows limited seedling resistance to a diverse set of exotic Pgt races but harbors valuable field resistance, including a strong locus for field resistance on chromosome 7AL. Abstract: The emergence and spread of Ug99 and other races of Puccinia graminis f. sp. tritici (Pgt) with virulence to widely deployed resistance genes threaten global wheat production. This study evaluated North American spring wheat germplasm for seedling responses to four Pgt races (TTKSK, TTKSF+, TKTTF, and TRTTF) and for field response across five environments in Ethiopia and Kenya. Seedling evaluation revealed significant race-specific variation, with 82% of the lines exhibiting resistance to race TKTTF but very limited resistance to the other races. Gene postulation based on resistance patterns suggested a high frequency of Sr7a (~ 92%) in this panel, with only a few lines (~ 5%) carrying Sr8a, Sr11, and/or Sr31. Field evaluations in Ethiopia and Kenya demonstrated quantitative variation for field response, with several lines showing consistent field resistance. Association mapping identified 37 significant associations for seedling resistance, representing 17 unique genomic regions. For field response, 15 significant associations were detected, including a region on chromosome arm 7AL that was consistently detected across environments. Further analysis indicated that this locus confers adult-plant resistance (APR) and might be independent of known stem rust resistance genes located in the region. Hence, KASP assay was developed to enable marker-assisted selection and further investigation of this locus. This study highlights limited seedling resistance but identifies promising sources of field resistance against exotic Pgt races and provides valuable insights into the genetics underlying both seedling and field responses in North American germplasm. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1007/s00122-026-05352-0.
SN - 0040-5752
SN - 1432-2242
ER -