Assessing dual resistance to stripe rust and powdery mildew in wheat germplasm through molecular and field studies across the north-western Himalayas

Wheat production in cooler regions like the north-western Himalayas, is significantly impeded by devastating diseases, namely stripe rust (SR) and powdery mildew (PM). Genetic resistance against SR and PM loses effectiveness over time which underscores the importance of periodic disease screening. This study aims to assess resistance to SR and PM in 81 wheat genotypes across multiple locations over three years (2019–20, 2021–22 and 2022–23); and detect candidate genes (Yr5, Yr10 and Pm24) for resistance using respective molecular markers viz., SSR/STS primers (STS7/8, Xp3000 and Xgwm337). The resistance towards SR and PM under natural epiphytotic conditions was displayed by eight and twelve genotypes respectively, across all locations. Notably, four genotypes (DH 202, HPW 368, HPW 373 and DH 114) were found resistant to both diseases. The phenotypic disease reaction for SR and PM was further validated through molecular markers. Genotypes DH 202, DH208, DH 217, CIMMYT Entry no. 23 and VL 829 emerged as high yielding disease resistant genotypes. Agrometeorological parameters specifically, precipitation and relative humidity exhibited significant positive correlations with disease incidence, leading to reduced grain yields. Genotype and genotype by environment interaction (GGE) biplot identified stable genotypes with less disease incidence over locations. Additionally, Kukumseri may serve as the optimal test site for screening wheat germplasm against SR, while Palampur and Kukumseri could be ideal for PM screening. Genotypes exhibiting combined disease resistance to both SR and PM, alongwith superior agronomic traits, hold promise for immediate deployment as wheat varieties or as potential donors for breeding resistant cultivars.