Microsatellite mapping of a leaf rust resistance gene transferred to common wheat fromTriticum timopheevii

Abstract

A leaf rust resistance gene transferred from the tetraploid wheat \ud Triticum timopheevii\ud (Zhuk.) Zhuk. (genomic composition: A\ud t\ud A\ud t\ud GG) into common wheat \ud Triticum aestivum\ud L. conditioned resistance at the seedling and adult plant stages in the introgression line ‘line 842-2’. To determine chromosome location and to map the resistance gene an F\ud 2\ud population from a cross between ‘line 842-2’ and susceptible wheat cultivar ‘Skala’ was developed and screened against leaf rust pathotype 77 (\ud Puccinia triticina\ud Erikss.). Microsatellite markers detected introgressions of the \ud T. timopheevii\ud genome on chromosomes 1A, 2A, 2B, 5B and 6B of ‘line 842-2’. Linkage analysis revealed an association between leaf rust resistance and microsatellite markers located on chromosome 5B. The markers \ud Xgwm880\ud and \ud Xgwm1257\ud were closely linked to the resistance gene with genetic distances of 7.7 cM and 10.4 cM, respectively. Infection type tests with three leaf rust isolates resulted in different patterns of infection types of ‘line 842-2’ and ‘Thatcher’ near-isogenic line with the \ud Lr18\ud gene on chromosome 5B. The data corroborated the hypothesis of the diversity of the resistance coming from \ud T. timopheevii\ud . The resistance gene of the introgression ‘line 842-2’ seems to be different than \ud Lr18\ud and therefore it was designated \ud LrTt2\ud