Development of PCR markers for the selection of wheat stem rust resistance genes Sr24 and Sr26 in diverse wheat germplasm

Abstract

The use of major resistance genes is the most cost-effective strategy for preventing stem rust epidemics in Australian wheat crops. The long-term success of this strategy is dependent on combining resistance genes that are effective against all predominant races of the pathogen, a task greatly assisted by the use of molecular markers linked to individual resistance genes. The wheat stem rust resistance genes Sr24 and Sr26 (derived from Agropyron elongatum) and SrR and Sr31 (derived from rye) are available in wheat as segments of alien chromosome translocated to wheat chromosomes. Each of these genes provides resistance to all races of wheat stem rust currently found in Australia . We have developed robust PCR markers for Sr24 and Sr26 (this study) and SrR and Sr31 (previously reported) that are applicable across a wide selection of Australian wheat germplasm. Wheat lines have recently become available in which the size of the alien segments containing Sr26, SrR and Sr31 has been reduced. Newly developed PCR-markers can be used to identify the presence of the shorter alien segment in all cases. Assuming that these genes have different gene-for-gene specificities and that the wheat industry will discourage the use of varieties carrying single genes only, the newly developed PCR markers will facilitate the incorporation of two or more of the genes Sr24, Sr26, SrR and Sr31 into wheat lines and have the potential to provide durable control to stem rust in Australia and elsewhere.

Wheat germplasm screening for stem rust resistance using conventional and molecular techniques

“…PCR was performed as described by Chen et al (1998). DNA samples from the parents and breeding lines were screened using STS marker Sr24#12, which co-segregates with the Sr24/Lr24 locus (Mago et al 2005) and is used for identification of wheat lines in breeding populations with resistance to stem rust. PCR products were resolved on 8% polyacrilamide gels stained with ethidium bromide.…”

Identification of Sr genes in new common wheat sources of resistance to stem rust race Ug99 using molecular markers

“…В настоящее время эти маркеры широко используются для скрининга сортов в США и международном центре СИММИТ (William et al, 2007;Singh et al, 2008). Диа-гностические фрагменты размером 500 и 200 п. н. для Sr24#12 и Sr24#50 соответственно (Mago et al, 2005) были выявлены у положительного контроля (линии BTSR24AG) и у линии GT 96/90, что свидетельствует о наличии у нее данного гена.…”

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

“…Two markers were evaluated for Sr26 (Mago et al, 2005;Liu et al, 2010). Marker Xsr26#43 amplified a 233bp fragment from WA-1, and an amplicon did not appear (null allele) in the other accessions tested.…”

“…Markers linked to resistance genes Sr2, Sr22,Sr26,Sr32,Sr35,Sr39, and Sr40 have been reported (Hayden et al, 2004;Khan et al, 2005;Mago et al, 2005;Babiker, 2006;Dundas et al, 2007;McNeil et al, 2008;Yu et al, 2009;Mago et al, 2009;Liu et al, 2010;Mago et al, 2010;Wu et al, 2009;Niu et al, 2011;Periyannan et al, 2011), but most of these markers were identified using a specific bi-parental mapping population, and levels of polymorphism for these markers may vary with parents.…”