Identification and molecular mapping of resistance genes for adult-plant resistance to stripe rust in spring wheat germplasm line PI660076

Abstract Wheat is one of the major food crops worldwide. Stripe rust can cause a great loss of wheat yield, especially when the disease is prevalent. Chemical control not only causes the loss of resistance to stripe rust but also has a serious impact on the human body and environment. Therefore, the most economical measure to control wheat stripe rust is to cultivate resistant varieties. Rapid variation of stripe rust races often leads to rapid "loss" of resistance to stripe rust disease; therefore, breeders and researchers have to continuously explore new stripe rust resistance genes to provide new resistance sources for the rapid variation of stripe rust races. Previous studies have confirmed that PI660076, a spring wheat line, showed stripe rust resistance under natural conditions at the adult stage, which has great value in breeding programs. In this study, a recombinant inbred lines (RIL) population was constructed by crossing the wheat line PI660076 with the stripe rust-susceptible line AvS. Genotyping of the population was performed using a wheat 15 K SNP array. Three QTLs were identified using phenotypic data over four years across three environments. The resistance type of each QTL was determined by inoculating the RIL lines with single and homozygous QTL during the seedling and adult stages under controlled conditions. The all-stage resistance (ASR) QTL, QYr076.jaas-2A (flanked by SNP marker AX-11048464 and Kompetitive Allele-Specific PCR (KASP) marker KASP_4940) explained 7.13–16.58% and 6.95–7.25% of infection type (IT) and disease severity (DS), respectively. The adult-plant resistance (APR) resistance QTL, QYr076.jaas-4D.1 (flanked by KASP marker KASP_0795 and SNP marker AX-111567243,) explained 6.85–12.70% and 7.94–17.26% of IT and DS, respectively. The APR resistance QTL, QYr076.jaas-4D.2 flanked by KASP markers KASP_9130 and KASP_6535, explained 7.97–39.19% and 8.77–20.55% of the phenotypic variation in IT and DS, respectively. All the three QTLs are likely to be new. The obtained results lay a foundation for further utilization of the stripe rust-resistant line PI660076, as well as for fine mapping and molecular marker-assisted selection breeding. Graphical Abstract