ARS | Publication request: Chromosome engineering to enhance utility of alien-derived stem rust resistance

Submitted to: International Wheat Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 28, 2008
Publication Date: August 24, 2008
Citation: Xu, S.S., I.S. Dundas, M.O. Pumphrey, Y. Jin, J.D. Faris, X. Cai, L.L. Qi, B.R. Friebe, and B.S. Gill. 2008. Chromosome engineering to enhance utility of alien-derived stem rust resistance. In: R. Appels, R. Eastwood, E. Lagudah, P. Langridge, M. Mackay, L. McIntye, and P. Sharp (Eds.) Proc. 11th Int. Wheat Genet. Symp., vol. 1. Sydney University Press, Sydney, Australia. Pp 12-14.

Technical Abstract: In the past 50 years, a number of stem rust (Sr) resistance genes identified from wild relatives of wheat have been incorporated into wheat genomes through chromosome engineering. Some of these genes, including Sr25, Sr26, Sr32, Sr37, Sr39, Sr40, Sr43, Sr44, SrR, and three unnamed novel Sr genes from Ae. speltoides and Haynaldia villosa, are highly effective against Ug99. However, the alien chromosomal segments possess deleterious genes in addition to the Sr genes in most of the introgression lines. To enhance the utility of these Sr genes in wheat breeding, we have been eliminating the deleterious linkage drag associated with these Sr genes through homoeologous recombination. The ph1b mutant was used to induce recombination between the alien chromosomal segments and their homoeologs in wheat. Recombinants with reduced alien chromatin were identified and characterized through stem rust testing, molecular marker analysis, and fluorescent genomic in situ hybridization. To date, several resistant lines with modified or shortened alien chromosomal segments have been developed. Lines containing modified alien chromosome segments with genes SrR, Sr26, Sr32 and Sr39 are undergoing backcrossing and field evaluation for yield and quality characteristics in wheat breeding programs.