Precise mapping of high-temperature adult-plant stripe rust resistance gene Yr52 in wheat

The HTAP stripe rust resistance gene Yr52 was mapped to a 2.5 8 Mb region and significantly enhanced adult plant stripe rust resistance when combined with QYr.nwafu 6B S .6. Stripe rust is one of the most devastating diseases of wheat. Resistant cultivars are the most economically effective control method. Spring wheat germplasm PI 660057 (carrying Yr52) remained resistant to stripe rust in China. In this study, we developed 145 recombinant inbred lines (RILs) from a cross of PI 660057 and Kenong 9204. The RILs and parental lines were evaluated for stripe rust response across four field environments and genotyped using the GenoBaits WheatSNP16K array. Two stable QTLs from PI 660057 were identified on chromosome arms 6BS (QYr.nwafu-6BS.6) and 7BL (Yr52), with QYr.nwafu-6BS.6 likely being Yr78. The combination of Yr52 and QYr.nwafu-6BS.6 provided better resistance to stripe rust than either gene or QTL alone. To better characterize the genetic and molecular characteristics of Yr52, we utilized a population of 552 residual heterozygous lines (RHLs) to precisely localize Yr52 to a 1.19-cM interval on chromosome 7BL between markers XK7B-16 and XK7B-21. We also developed a co-segregating molecular marker for Yr52 and selected a series of Yr52-bearing lines with superior agronomic traits. These results lay a foundation for the map-based cloning of Yr52 and its subsequent application in gene pyramiding.