Stacking effective ASR and APR rust genes for multiple disease resistance in bread wheat cultivars

Abstract Rusts and powdery mildews pose serious threats to wheat and have caused substantial yield losses worldwide. Host resistance is the most economical and sustainable approach for managing such diseases. In this study, an effective leaf rust resistance gene Lr45-derived from Secale cereale L. and a linked stem rust and powdery mildew resistance gene Sr36/Pm6-derived from Triticum timopheevii were successfully pyramided. They were validated into well-adapted Indian wheat cultivars that were already carrying the APR stem rust gene Sr2/Lr27/Yr30 through marker-assisted backcross selection (MABC) following two parallel backcrossing schemes. Three efficiently linked microsatellite markers, G372185 (Lr45), Stm773-2(Sr36), and Xgwm533 (Sr2), were used to confirm introgression of these genes. Lines with resistance genes in each background showed improved agronomic traits in comparison to their recurrent parents. These lines could be used in wheat improvement programs as potentially resistant stocks for leaf, stem rusts and powdery mildew to develop new wheat cultivars.