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Introgression and characterization of a goatgrass gene for a high level of resistance to ug99 stem rust in tetraploid wheat.

ABSTRACT: The transfer of alien genes to crop plants using chromosome engineering has been attempted infrequently in tetraploid durum wheat (Triticum turgidum L. subsp. durum). Here, we report a highly efficient approach for the transfer of two genes conferring resistance to stem rust race Pgt-TTKSK (Ug99) from goatgrass (Aegilops speltoides) to tetraploid wheat. The durum line DAS15, carrying the stem rust resistance gene Sr47 derived from Ae. speltoides, was crossed, and backcrossed, to durum 5D(5B) aneuploids to induce homeologous pairing. After a final cross to 'Rusty' durum, allosyndetic recombinants were recovered. The Ae. speltoides chromosomal segment carrying Sr47 was found to have two stem rust resistance genes. One gene conditioning an infection type (IT) 2 was located in the same chromosomal region of 2BS as Sr39 and was assigned the temporary gene symbol SrAes7t. Based on ITs observed on a diverse set of rust races, SrAes7t may be the same as Sr39. The second gene conditioned an IT 0; and was located on chromosome arm 2BL. This gene retained the symbol Sr47 because it had a different IT and map location from other stem rust resistance genes derived from Ae. speltoides. Allosyndetic recombinant lines carrying each gene on minimal alien chromosomal segments were identified as were molecular markers distinguishing each alien segment. This study demonstrated that chromosome engineering of Ae. speltoides segments is feasible in tetraploid wheat. The Sr47 gene confers high-level and broad spectrum resistance to stem rust and should be very useful in efforts to control TTKSK.

SUBMITTER: Klindworth DL

PROVIDER: S-EPMC3362296 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Introgression and characterization of a goatgrass gene for a high level of resistance to ug99 stem rust in tetraploid wheat.

Klindworth Daryl L DL Niu Zhixia Z Chao Shiaoman S Friesen Timothy L TL Jin Yue Y Faris Justin D JD Cai Xiwen X Xu Steven S SS

G3 (Bethesda, Md.) 20120601 6

The transfer of alien genes to crop plants using chromosome engineering has been attempted infrequently in tetraploid durum wheat (Triticum turgidum L. subsp. durum). Here, we report a highly efficient approach for the transfer of two genes conferring resistance to stem rust race Pgt-TTKSK (Ug99) from goatgrass (Aegilops speltoides) to tetraploid wheat. The durum line DAS15, carrying the stem rust resistance gene Sr47 derived from Ae. speltoides, was crossed, and backcrossed, to durum 5D(5B) ane ...[more]

PMID: 22690376

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Project description:Wheat stem rust (Puccinia graminis f. sp. tritici Eriks. and E. Henn.) is one of the most destructive diseases world-wide. Races belonging to Ug99 (or TTKSK) continue to cause crop losses in East Africa and threaten global wheat production. Developing and deploying wheat varieties with multiple race-specific genes or complex adult plant resistance is necessary to achieve durability. In the present study, we applied genome-wide association studies (GWAS) for identifying loci associated with the Ug99 stem rust resistance (SR) in a panel of wheat lines developed at the International Maize and Wheat Improvement Center (CIMMYT). Genotyping was carried out using the wheat 9K iSelect single nucleotide polymorphism (SNP) chip. Phenotyping was done in the field in Kenya by infection of Puccinia graminis f. sp. tritici race TTKST, the Sr24-virulent variant of Ug99. Marker-trait association identified 12 SNP markers significantly associated with resistance. Among them, 7 were mapped on five chromosomes. Markers located on chromosomes 4A and 4B overlapped with the location of the Ug99 resistance genes SrND643 and Sr37, respectively. Markers identified on 7DL were collocated with Sr25. Additional significant markers were located in the regions where no Sr gene has been reported. The chromosome location for five of the SNP markers was unknown. A BLASTN search of the NCBI database using the flanking sequences of the SNPs associated with Ug99 resistance revealed that several markers were linked to plant disease resistance analogues, while others were linked to regulatory factors or metabolic enzymes. A KASP (Kompetitive Allele Specific PCR) assay was used for validating six marker loci linked to genes with resistance to Ug99. Of those, four co-segregated with the Sr25-pathotypes while the rest identified unknown resistance genes. With further investigation, these markers can be used for marker-assisted selection in breeding for Ug99 stem rust resistance in wheat.

Dataset Information

Introgression and characterization of a goatgrass gene for a high level of resistance to ug99 stem rust in tetraploid wheat.

Publications

Introgression and characterization of a goatgrass gene for a high level of resistance to ug99 stem rust in tetraploid wheat.

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