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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, Niu, Zhixia, Chao, Shiaoman, Friesen, Timothy L, Jin, Yue, Faris, Justin D, Cai, Xiwen, Xu, Steven S
Genes | Genomes | Genetics 2012 v.2 pp. 665
Aegilops speltoides, Triticum turgidum subsp. durum, backcrossing, chromosome pairing, chromosomes, disease resistance, durum wheat, genes, genetic markers, introgression, plant breeding, races, stem rust, tetraploidy
The transfer of alien genes to crop plants using chromosome engineering has been infrequently attempted 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 homoeologous 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, which retained the symbol Sr47, was located in the region carrying Sr9, though an allelic relationship was not established. Allosyndetic recombinant lines carrying each gene on minimal alien chromosomal segments were identified as were molecular markers distinguishing each alien segment. The Sr47 gene confers high-level and broad spectrum resistance to stem rust and should be very useful in efforts to control TTKSK. This study demonstrated that chromosome engineering of Ae. speltoides segments is feasible in tetraploid wheat, and is more successful when transferring genes from subtelomeric or telomeric regions.