|KIELSMEIER-COOK, JOSHUA - University Of Minnesota|
|DANILOVA, TATIANA - Kansas State University|
|FRIEBE, BERND - Kansas State University|
|Rouse, Matthew - Matt|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2015
Publication Date: 9/29/2015
Citation: Kielsmeier-Cook, J., Danilova, T.V., Friebe, B., Rouse, M.N. 2015. Resistance to the Ug99 race group of Puccinia graminis f. sp. tritici in wheat-intra/intergeneric hybrid derivatives. Plant Disease. 99:1317-1325.
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. We assessed the stem rust resistance in a collection of hybrid wheat lines created through crossing wheat with related species. We found several of these hybrid lines that possessed stem rust resistance including resistance to Ug99. Four of these hybrid lines were found to have the same number of chromosomes as wheat indicating that these lines could be used in wheat breeding. For three of these four lines, we hypothesize that the resistance to stem rust is conferred by previously undescribed resistance gene(s). The identification these new resistance sources 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: New races of Puccinia graminis f. sp. tritici, the causal agent of wheat stem rust, threaten global wheat production. In particular, races belonging to the Ug99 race group, threaten wheat yield. Genetic resistance remains the most effective means for controlling this disease. A collection of 546 wheat-intra/intergeneric hybrids developed by W. J. Sando were screened with eight races of P. graminis f. sp. tritici, including races TTKSK, TTKST, and TTTSK. 152 accessions were resistant to one or more races and 29 accessions were resistant to the three races of the Ug99 race group. Of these 29 accessions, 11 were resistant to all races used, 14 had infection type patterns that were indistinguishable from Sr9h and Sr42, 2 were indistinguishable from SrTmp, and 4 did not share patterns with any known Sr gene. Four accessions were characterized via GISH-FISH and were found to be disomic substitution lines, each with a single Thinopyrum ponticum chromosome pair. Three accessions examined are postulated to contain new resistance genes. This research indicates the value of extant collections of wheat-intergeneric hybrids as sources of disease resistance genes capable of being identified and rapidly introgressed into modern wheat cultivars.