Identification and Validation of Markers Linked to Broad‐Spectrum Stem Rust Resistance Gene Sr2 in Wheat (Triticum aestivum L.)

Stem rust resistance in wheat (Triticum aestivum L.) conferred by the Sr2 gene has remained effective against Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn. worldwide for more than 50 yr. Sr2 resistance is associated with variable levels of disease symptoms; it shows recessive inheritance and is expressed primarily during the adult‐plant stage. A genetic and physical interval for the Sr2 gene was determined on the short arm of chromosome 3B of wheat. Flanking microsatellite markers were identified and one tightly linked marker (gwm533) was shown to be associated with presence of Sr2 This marker was validated in a wide range of germplasm and can now be implemented in marker‐assisted breeding to facilitate selection for this durable, broad‐spectrum but difficult to score rust resistance gene.