Association of a stem rust resistance gene (Sr45) and two Russian wheat aphid resistance genes (Dn5 and Dn7) with mapped structural loci in common wheat

A stem rust resistance gene, originally derived from Triticum tauschii accession RL5289 and present in the germplasm line 87M66-2-1, is here designated Sr45. Sr45 was found to be closely linked to Sr33 (9 ± 1.9 map units) and the centromere (21 ± 3.4 map units) on chromosome arm 1DS. Sr45 is believed to be the same gene as SrX. The Russian wheat aphid resistance gene, Dn5, was loosely linked (32 ± 5 map units) to Ep-D1b, which occurs on a translocation derived from T. ventricosum, and to the cn?D1 locus (37 ± 6.3 map units) on chromosome arm 7DL. Dn5 derives from T. aestivum accession Pl294994 which was found to express two novel Ep-1 alleles (proposed designations Ep-A1d and Ep-D1e). A gene (here designated Dn7) for Russian wheat aphid resistance that was derived from the rye accession, Turkey 77', mapped 14.5 ± 3.9 map units from Lr26 on the 1BL.1RS translocation.