Molecular Mapping of a Novel Quantitative Trait Locus Conferring Adult Plant Resistance to Stripe Rust in Chinese Wheat Landrace Guangtoumai.

Stripe rust (yellow rust), caused by f. sp. , is one of the most destructive diseases of wheat worldwide. Chinese wheat landrace Guangtoumai (GTM) exhibited a high level of resistance against predominant f. sp. races in China at the adult plant stage. The objective of this research was to identify and map the major locus/loci for stripe rust resistance in GTM. A set of 212 recombinant inbred lines (RILs) was developed from a cross between GTM and Avocet S. The parents and RILs were evaluated in three field tests (2018, 2019, and 2020 at Chongzhou, Sichuan) with the currently predominant f. sp. races for final disease severity and genotyped with the Wheat 55K single nucleotide polymorphism (SNP) array to construct a genetic map with 1,031 SNP markers. A major locus, named , was detected on chromosome 5DL in GTM. The locus was mapped in a 2.75-cM interval flanked by SNP markers and , explaining up to 44.4% of the total phenotypic variation. Since no known genes have been reported on chromosome 5DL, is very likely a novel adult plant resistance locus. Haplotype analysis revealed that the resistance allele displayed enhanced levels of stripe rust resistance and is likely present in 5.3% of the 247 surveyed Chinese wheat landraces. The derived cleaved amplified polymorphic sequence (dCAPS) marker , converted from a SNP marker tightly linked to with 0.3 cM, was validated on a subset of RILs and 48 commercial wheat cultivars developed in Sichuan. The results indicated that with its linked dCAPS marker could be used in marker-assisted selection to improve stripe rust resistance in breeding programs, and this quantitative trait locus will provide new and possibly durable resistance to stripe rust.