Introgression of stem rust resistance genes SrTA10187 and SrTA10171 from Aegilops tauschii to wheat.
ABSTRACT Aegilops tauschii, the diploid progenitor of the wheat D genome, is a readily accessible germplasm pool for wheat breeding as genes can be transferred to elite wheat cultivars through direct hybridization followed by backcrossing. Gene transfer and genetic mapping can be integrated by developing mapping populations during backcrossing. Using direct crossing, two genes for resistance to the African stem rust fungus race TTKSK (Ug99), were transferred from the Ae. tauschii accessions TA10187 and TA10171 to an elite hard winter wheat line, KS05HW14. BC2 mapping populations were created concurrently with developing advanced backcross lines carrying rust resistance. Bulked segregant analysis on the BC2 populations identified marker loci on 6DS and 7DS linked to stem rust resistance genes transferred from TA10187 and TA10171, respectively. Linkage maps were developed for both genes and closely linked markers reported in this study will be useful for selection and pyramiding with other Ug99-effective stem rust resistance genes. The Ae. tauschii-derived resistance genes were temporarily designated SrTA10187 and SrTA10171 and will serve as valuable resources for stem rust resistance breeding.
SourceAvailable from: Mark E Sorrells[Show abstract] [Hide abstract]
ABSTRACT: This consensus map of stem rust genes, QTLs, and molecular markers will facilitate the identification of new resistance genes and provide a resource of in formation for development of new markers for breeding wheat varieties resistant to Ug99. The global effort to identify new sources of resistance to wheat stem rust, caused by Puccinia graminis f. sp. tritici race group Ug99 has resulted in numerous studies reporting both qualitative genes and quantitative trait loci. The purpose of our study was to assemble all available information on loci associated with stem rust resistance from 21 recent studies on Triticum aestivum L. (bread wheat) and Triticum turgidum subsp. durum desf. (durum wheat). The software LPmerge was used to construct a stem rust resistance loci consensus wheat map with 1,433 markers incorporating Single Nucleotide Polymorphism, Diversity Arrays Technology, Genotyping-by-Sequencing as well as Simple Sequence Repeat marker information. Most of the markers associated with stem rust resistance have been identified in more than one population. Several loci identified in these populations map to the same regions with known Sr genes including Sr2, SrND643, Sr25 and Sr57 (Lr34/Yr18/Pm38), while other significant markers were located in chromosome regions where no Sr genes have been previously reported. This consensus map provides a comprehensive source of information on 141 stem rust resistance loci conferring resistance to stem rust Ug99 as well as linked markers for use in marker-assisted selection.Theoretical and Applied Genetics 06/2014; 127(7). DOI:10.1007/s00122-014-2326-7 · 3.51 Impact Factor
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ABSTRACT: Wheat stem rust resistance gene SrWeb is an allele at the Sr9 locus that confers resistance to Ug99. Race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the causal fungus of stem rust, threatens global wheat production because of its broad virulence to current wheat cultivars. A recently identified Ug99 resistance gene from cultivar Webster, temporarily designated as SrWeb, mapped near the stem rust resistance gene locus Sr9. We determined that SrWeb is also present in Ug99 resistant cultivar Gabo 56 by comparative mapping and an allelism test. Analysis of resistance in a population segregating for both Sr9e and SrWeb demonstrated that SrWeb is an allele at the Sr9 locus, which subsequently was designated as Sr9h. Webster and Gabo 56 were susceptible to the Ug99-related race TTKSF+ from South Africa. Race TTKSF+ possesses unique virulence to uncharacterized Ug99 resistance in cultivar Matlabas. This result validated that resistance to Ug99 in Webster and Gabo 56 is conferred by the same gene: Sr9h. The emergence of pathogen virulence to several resistance genes that are effective to the original Ug99 race TTKSK, including Sr9h, suggests that resistance genes should be used in combinations in order to increase resistance durability.Theoretical and Applied Genetics 06/2014; DOI:10.1007/s00122-014-2330-y · 3.51 Impact Factor
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ABSTRACT: Biotic stresses including diseases (leaf, stem and stripe rusts), arthropods (greenbug [GB], Hessian fly [Hf], Russian wheat aphid [RWA], and wheat curl mite [WCM]) and their transmitted viral diseases significantly affect grain yield and end-use quality of hard winter wheat (Triticum aestivum L.) in the U.S. Great Plains. Many genes or quantitative trait loci (QTL) have been identified for seedling or adult-plant resistance to these stresses. Molecular markers for these genes or QTL have been identified using mapping or cloning. This study summarizes the markers associated with various effective genes, including genes or QTL conferring resistances to arthropods, such as GB (7), RWA (4), Hf (9), and WCM (4) and diseases including leaf, stem and stripe rusts (26) and Wheat streak mosaic virus (WSMV; 2); genes or QTL for end-use quality traits such as high (3) and low (13) molecular weight glutenin subunits, gliadin (3), polyphenol oxidase (2), granule-bound starch synthase (3), puroindoline (2), and preharvesting sprouting (1); genes on wheat–rye (Secale cereale L.) chromosomal translocations of 1AL.1RS and 1BL.1RS; and genes controlling plant height (12), photoperiod sensitivity (1), and vernalization (2). A subset of the markers was validated using a set of diverse wheat lines developed by breeding programs in the Great Plains. These analyses showed that most markers are diagnostic in only limited genetic backgrounds. However, some markers developed from the gene sequences or alien fragments are highly diagnostic across various backgrounds, such as those markers linked to Rht-B1, Rht-D1, Ppd-D1, Glu-D1, Glu-A1, and 1AL.1RS. Knowledge of both genotype and phenotype of advanced breeding lines could help breeders to select the optimal parents to integrate various genes into new cultivars and increase the efficiency of wheat breeding.Crop Science 07/2014; 54(4-4):1304-1321. DOI:10.2135/cropsci2013.08.0564 · 1.48 Impact Factor