|PUJOL, VINCENT - Commonwealth Scientific And Industrial Research Organisation (CSIRO)|
|FORREST, KERRIE - Department Of Environment And Primary Industries|
|ZHANG, PENG - University Of Sydney|
|Rouse, Matthew - Matt|
|HAYDEN, MATTHEW - Department Of Environment And Primary Industries|
|JONES, DAVID - Australian National University|
|TABE, LINDA - Commonwealth Scientific And Industrial Research Organisation (CSIRO)|
|LAGUDAH, EVANS - Commonwealth Scientific And Industrial Research Organisation (CSIRO)|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2015
Publication Date: 4/16/2015
Citation: Pujol, V., Forrest, K., Zhang, P., Rouse, M.N., Hayden, M.J., Jones, D., Tabe, L., Lagudah, E. 2015. Mapping of a stem rust resistance locus effective against Ug99 on wheat chromosome 7AL using a RAD-Seq approach. Theoretical and Applied Genetics. 128:1397-1405.
Interpretive Summary: Wheat stem rust is a fungal disease of wheat that decreases yield. A strain of the wheat stem rust fungus known as Ug99 emerged in Uganda in 1999 and threatens global wheat production because it is able to infect nearly all wheat varieties. United States spring wheat possesses resistance to stem rust derived from cultivar 'Thatcher'. We identified a stem rust resistance gene in cultivar 'Canthatch' which is related to 'Thatcher'. The resistance gene was identified using new genotyping methods. The identification this gene on wheat chromosome arm 7AL will facilitate the improvement of resistance of United States wheat cultivars to the dangerous Ug99. Ug99 resistant wheat cultivars will protect United States wheat production from yield loss if a Ug99 epidemic were to occur in the United States.
Technical Abstract: Wheat stem rust is responsible for major production losses around the world. The development of resistant cultivars is an effective way to manage the disease, but outbreaks can occur when new pathogen races overcome the existing resistances. Ug99 (race TTKSK), and related newly-emerged, highly virulent stem rust races, present a potential threat to global wheat production. The hexaploid wheat cultivar Canthatch has long been known for carrying a suppressor of stem rust resistance on chromosome arm 7DL. Multiple “non-suppressor” mutants of Canthatch were reported to have gained resistance to stem rust races that were recently found to include Ug99 (TTKSK) and related races TTKST and TTTSK. In order to genetically map the suppressor, a mapping population was developed from a cross between the susceptible cultivar Columbus, thought to possess the suppressor, and the resistant Columbus-NS766, a near-isogenic line believed to contain a mutant, non-suppressor allele introgressed from Canthatch. Molecular markers used in mapping were based on two recently developed techniques: i) the 9k iSelect SNP genotyping assay and ii) restriction-site associated DNA sequencing (RAD-Seq) on bulked segregants. These methods led to the rapid identification of markers putatively linked to the stem rust resistance. Surprisingly, genomic sequence information revealed the markers to be located on 7AL, not 7DL, indicating that the phenotype was due to a new resistance locus, rather than the inacti-vated suppressor. We suggest that the 7AL locus is most likely the resistance locus repressed by the 7DL suppressor.