Molecular Mapping of Stem Rust Resistance in HD2009/WL711 Recombinant Inbred Line Population

The Indian wheat cultivar ‘HD2009’ exhibited moderate level of stem rust resistance both under Indian and Australian conditions since its release in 1976. Ninety two ‘HD2009’/‘WL711’-derived recombinant inbred lines (RILs) were tested in the field for three years against Puccinia graminis f. sp. tritici. Genetic analyses indicated the presence of three to four genes for resistance across all sites over three years, except at the Lansdowne site during 2004, where resistance was controlled by two to three genes. A linkage map using 46 SSR and 295 DArT markers was generated and used for molecular mapping of stem rust resistance carried by ‘HD2009’. Three consistent QTLs; QSr.sun-3BS, QSr.sun-5DL and QSr.sun-7A were identified. QSr.sun-3BS explained 9-15% phenotypic variation and was concluded to be Sr2. The most significant QTL, QSr.sun-5DL, corresponded to the previously reported location of Sr30 and explained 20-44% phenotypic variation in adult plant stem rust response. The contribution of QSr.sun-7A was almost equal to QSr.sun-3BS (7-13%). Additional inconsistent QTLs, QSr.sun-1D, QSr.sun-2B, QSr.sun-4B and QSr.sun-5B were also detected. All QTLs, except QSr.sun-4B, were contributed by ‘HD2009’. QSr.sun-4B was contributed by ‘WL711’. The physiological trait, pseudo-black chaff (PBC), which is reported to be linked with adult plant stem rust resistance gene Sr2, was controlled by QTLs, QPbc.sun-3BS, QPbc.sun-5DL and QPbc.sun-7DS. QPbc.sun-5DL and QPbc.sun-7DS corresponded to the locations of Sr30 and Lr34, respectively. _____________________________________________________________________________________________________________