ARS | Publication request: Introgression of stem rust resistance genes SrTA10187 and SrTA10171 from Aegilops tauschii to wheat

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 9, 2013
Publication Date: N/A

Interpretive Summary: Goat grass (Aegilops tauschii) is a progenitor species of modern bread wheat. This species has contributed many genes for resistance to disease and insect pest of wheat that are currently used in wheat breeding efforts. In a previous study, a collection of jointed goat grass was evaluated for resistance to a new and highly virulent race of wheat stem rust (“Ug99”). The Ug99 race of stem rust can infect most of the wheat varieties in the US and the world. Several accessions of goat grass were found to be resistant to Ug99. In this study we crossed two of the resistant accessions with an elite hard winter wheat from Kansas. Resistant plants from this cross were selected and crossed again to the Kansas wheat. Following repeated selection for resistant plants and crossing to wheat, we developed two wheat germplasm lines with resistance to Ug99. Using a segregating population and molecular DNA markers, these two genes were mapped to wheat chromosomes 6D and 7D. These two new genes, designated Sr10187 (TA10187) and Sr10171 (TA10171) will be useful for breeding varieties with resistance to Ug99 stem rust.

Technical Abstract: The diploid progenitor of the wheat D genome, Aegilops tauschii, has provided a wealth of genes for resistance to many diseases and insect pests of wheat. Ae. tauschii is a readily accessible pool of genes for wheat breeding as genes can be transferred to elite wheat cultivars though direct hybridization followed by backcrossing. Gene transfer and genetic mapping can be integrated by developing mapping populations during backcrossing. Using direct crossing, two novel genes for resistance to the Ug99 stem rust fungus, race TTKSK, were transferred from the Ae. tauschii accessions TA10187 and TA10171 into an elite hard winter wheat line, KS05HW14. Concurrent with developing advanced backcross lines with stem rust resistance, BC2 mapping populations were created. Bulked segregant analysis on the BC2 populations identified 6DS and 7DS as the chromosome locations of stem rust resistance genes transferred from TA10187 and TA10171, respectively. Using the full BC2 populations, linkage maps were developed for both genes and closely linked markers were identified that will be useful for selection and pyramiding with other Ug99-effective Sr genes. The new Ae. tauschii-derived resistance genes have been temporarily designated Sr10187 (TA10187) and Sr10171 (TA10171) and will serve as a valuable resource for stem rust resistance breeding.