Genetic mapping and utilization analysis of stripe rust resistance genes in a Tibetan wheat (Triticum aestivumL.) landrace Qubaichun

Stripe rust, which is caused byPuccinia striiformisf. sp. Tritici(Pst), is one of the most destructive wheat (Triticum aestivumL.) diseases worldwide. To control stripe rust, the best strategy is breeding and growing novel resistant cultivars. Qubaichun (QBC), a Tibetan wheat landrace, displays near-immune resistance to wheat stripe rust in western China. Previously, our studies have shown that the stripe rust resistance of QBC is controlled by a dominant gene at the seedling stage and two independent genes at the adult-plant stage. These two genes comprise an all-stage resistance (ASR) gene and a durable adult resistance gene, which was identified asYr18. The unknown ASR gene is temporarily namedYrqbc. To map this gene, a segregating population of QBC x Chinese Spring (CS) was generated. SSR analysis, BSR-seq and Infinium 660 K iSelect SNP genotyping were successively performed. The results show thatYrqbcfinely mapped to a 5.1 cM genetic interval between molecular markers A009200 and A009192, and the genetic distance to the marker A009200 was 0.1 cM. Furthermore,Yrqbcwas confirmed to beYr5by sequencing. Diagnostic markers are used for detectionYr5andYr18in 323 new cultivars (lines) worldwide. The results show that 27 cultivars (lines) carry the durable adult resistance geneYr18, and only one material carrying the ASR resistance geneYr5. In order to analyse the effectiveness and practicality of transferring the pyramided ofYr18andYr5, these two stripe rust resistance genes were introduced into elite cultivars which lost resistance. Field test results verified that the combination ofYr5andYr18could provide effective resistance to stripe rust for the whole life of wheat, which provided a genetic foundation for the near immunity of elite cultivars. As a result, this Tibetan landrace could be used for developing high-level, durable resistant wheat cultivars.