Molecular and Cytogenetic Characterization of Wheat Introgression Lines Carrying the Stem Rust Resistance Gene Sr39

Abstract

The stem rust (Puccinia graminis Pers.:Pers. f.sp. tritici Eriks. and Henn.) resistance gene Sr39, which confers resistance to TTKSK (Ug99), has been incorporated into the wheat (Triticum aestivum L.) genome from Aegilops speltoides in the form of a chromosome translocation but it has not been deployed into adapted cultivars. In this study, we characterized translocation lines carrying Sr39 in four different wheat backgrounds with fluorescent genomic in situ hybridization (GISH) and simple sequence repeat (SSR) markers. The results indicated that RL5711 and RL6082 had translocation chromosomes of comparable structure. The translocation chromosome in PI 600683 has lost Ae. speltoides chromatin in the telomeric end of the 2S long arm. Six translocation lines derived from the cross PI 600683/3*HY438 had translocation chromosomes of comparable structure to the one found in PI 600683. However, one line (P9714‐AM03C51), showed a substantial reduction in Ae. speltoides chromatin in the short arm of the translocated chromosome. The study demonstrated that it is apparently feasible to shorten Ae. speltoides chromatin in some wheat‐Ae. speltoides translocation lines. These results and the identification of diagnostic SSR markers will be useful in guiding chromosome manipulation efforts to further shorten the Ae. speltoides chromosome segments in these materials. Greenhouse inoculation of translocation lines with stem rust indicated that the Sr39 gene conditions resistance to at least seven stem rust races.

Targeted Introgression of a Wheat Stem Rust Resistance Gene by DNA Marker-Assisted Chromosome Engineering

“…speltoides chromosome segment, but the translocation chromosome still retained $80-85% of the Ae. speltoides chromatin (Yu et al 2010). All other lines contained similar amounts of Ae.…”

“…Later, Sr39 and Lr35 were transferred from RL5711 into wheat line RL6082 through six backcrosses using wheat cultivar Thatcher as the recurrent parent (Seyfarth et al 1999). The translocated chromosome T2B/2S#2 consisted of the 2S long arm, a large portion ($85%) of the 2S short arm, and a small terminal 2B segment (Yu et al 2010). To make Sr39 usable to fight Ug99, the excess Ae.…”

“…In addition to the wheat lines reported by Mago et al (2009), R. E. Knox developed a set of breeding lines carrying Lr35/Sr39 from the original translocation line (Knox et al 2000;Yu et al 2010). One line had a slightly shortened Ae.…”

Validation of Molecular Markers for New Stem Rust Resistance Genes in U.S. Hard Winter Wheat

“…All resistance gene donors have been confirmed for rust resistance (Dundas et al, 2007;Jin et al, 2007;Yu et al, 2010) and all recently released cultivars do not contain any new alien resistance genes listed in this study according to their release documents. The cultivar 2174 was reported to be negative for Sr2 , Thunder CL was reported to be positive for Sr2 (Haley et al, 2009), but the status of the others is unknown.…”

“…The Sr35 resistance gene from T. monoccocum was transferred to chromosome 3AL of Mq(2)5*G2919K (Zhang et al, 2010). Two markers, Xbarc51 and Xcfa2076, were reported to link to the gene (Babiker, 2009;Yu et al, 2009).…”