Exploiting phKL-mediated homoeologous recombinants to map stripe rust resistance gene YrAev from Aegilops variabilis

Aegilops variabilis(SvSvUvUv) is a source of resistance to wheat stripe rust. ThephKL locus in Chinesecommon wheatlandraceKaixian-Luohanmai (KL) can induce homoeologous wheat-alienchromosome pairingand recombination. In this study, we confirmed that the whole 2Svchromosome introgressed into wheat from Ae. variabilis accession AS116 conferred all-stage stripe rust resistance. The underlying gene(s), namedYrAev, was mapped to the long arm 2SvL using an F2population. Two 2Sv-2B recombinants, derived from a cross of the 2Sv(2B) chromosomesubstitution lineand KL, were confirmed to harbor the resistance locus. The physical region containing YrAev, determined from RNA-seq data, was 844.6–852.1 Mb on thechromosome arm 2Slof the Ae. longissima (Svgenome donor species ofAe. variabilis) accession TL05 assembly v1.0. Differentialgene expression analysisof post-inoculation with thePstrace has indicated two disease-resistance-related genes (annotated as mixedlineagekinase domain-like protein and nucleotide-binding leucine-rich repeat like protein, respectively) as promising candidates forYrAev. This study demonstrates the utility of thephKLgene system in alien gene localization and transfer. The resistanttranslocation lineharboringYrAevcan be exploited by wheat breeders as a novel source of resistance to stripe rust.