ARS | Publication request: Molecular marker-assisted alien gene introgression of Sr39 for wheat stem rust resistance derived from Aegilops speltoides

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 26, 2010
Publication Date: December 10, 2010
Citation: Niu, Z., Klindworth, D.L., Friesen, T.L., Chao, S., Jin, Y., Cai, X., Xu, S.S. 2011. Molecular marker-assisted alien gene introgression of Sr39 for wheat stem rust resistance derived from Aegilops speltoides. Meeting Abstract. 195.

Technical Abstract: In wheat (Triticum aestivum L.), stem rust resistance gene Sr39, derived from Aegilops speltoides, is highly effective against multiple stem rust races including Ug99. However, the gene has not been used in wheat breeding because it is located on a large 2S chromosomal segment in the current translocation stocks RL5711 and RL6082. To make this valuable gene usable to wheat breeders, we have conducted research focusing on reducing the size of the alien chromosome segment surrounding Sr39 using chromosome engineering in conjunction with stem rust testing and high-throughput marker technology. In this procedure, the ‘Chinese Spring’ (CS) ph1b mutant was crossed to translocation stock RL6082 and then backcrossed to the F1 hybrids. Resistant BC1F1 plants homozygous for ph1b were backcrossed to CS. From 1,048 BC2F1 plants tested with stem rust and a co-dominant microsatellite marker, we identified 40 resistant plants with complete dissociation of the marker linked to the large alien chromosome segment. Four wheat lines (RWG1, RWG2, RWG3 and RWG4) carrying Sr39 on very short alien chromosomal segments have been identified and verified using fluorescent genomic in situ hybridization. Based on the sequences of the deletion bin-mapped wheat ESTs and the collinear region of the rice genome, we developed three co-dominant STS (sequence tagged site) markers tightly linked to Sr39 on short alien chromatin. The new wheat germplasm lines and Sr39-linked STS markers are important resources for breeding wheat cultivars resistant to Ug99 and other races of stem rust.