Marker-assisted backcross breeding to develop wheat lines with stable yellow rust resistance without yield penalties

Abstract

Wheat production faces severe yield threats globally and regionally in India from rust diseases caused by Puccinia species. Genetic resistance breeding is the most sustainable approach to mitigate these losses, but traditional phenotypic selection is often constrained by environmental fluctuations and rapid pathogen evolution. Here we utilized marker-assisted backcross breeding (MABB) to introgress broad-spectrum yellow rust resistance genes, Yr10 and Yr15, from the donor genetic stock PBW703 into the elite, high-yielding wheat cultivar DBW88 to develop two high-yielding rust-resistant genotypes DBW476 and DBW477. Foreground selection was executed using gene-linked molecular markers PSP3000 (Yr10) and Xbarc8 (Yr15). Background selection with 107 polymorphic simple sequence repeat (SSR) markers accelerated recurrent parent genome recovery up to 95% within just two backcross generations, significantly outperforming conventional breeding timelines. Seedling resistance tests and adult plant resistance evaluations confirmed that the introgressed lines exhibited a high degree of immune response and comprehensive resistance against virulent Puccinia striiformis pathotypes, including 238S119 and 110S119. Multi-year agronomic testing across multiple environments demonstrated that the improved near-isogenic lines achieved equal or superior grain yield performance compared to their recurrent parents and commercial checks. These findings indicate successful gene introgression without any associated linkage drag or yield penalties. These advanced, stable lines were nominated for multi-location varietal trials, presenting a strategically superior asset for sustainable rust management and food security in the rust-prone environments of India.