Mapping Stripe Rust Resistance QTL in 'N2496', a Synthetic Hexaploid Wheat Derivative

Stripe rust is a destructive disease that affects plant growth and substantially reduces wheat yields globally. An economically and environmentally friendly way to control this disease is to use resistant cultivars. 'N2496' is a synthetic hexaploid wheat derivative that exhibits high resistance and could serve as a source of resistance for breeding programs. We developed three recombinant inbred lines (RILs) populations by crossing 'N2496' with common wheat cultivars 'CN16', 'CM107', and 'MM37'. Stripe rust responses were evaluated in all three populations using a mixture of current predominant Chinese Puccinia striiformis f. sp. tritici races. A stripe rust resistance quantitative trait locus (QTL) in the 'N2496'/'CN16' RIL population was mapped on chromosome arm 6BL at 519.35 to 526.55 Mb using bulked segregant RNA sequencing. The population was genotyped using simple sequence repeats and kompetitive allele-specific polymerase (KASP) markers. The QTL QYr.sicau-6B was localized to a 1.19-cM interval flanked by markers KASP-TXK-10 and KASP-TXK-6. The genetic effect of QYr.sicau-6B was validated in the 'N2496' × 'CM107' and 'N2496' × 'MM37' RILs populations and explained up to 63.16% of the phenotypic variation. RNA sequencing and quantitative real-time polymerase chain reaction identified two differentially expressed candidate genes in the physical interval of QYr.sicau-6B.