Fine mapping of two recessive powdery mildew resistance genes from Aegilops tauschii accession CIae8

Abstract Wheat powdery mildew (Pm), one of the worldwide destructive fungal diseases, could cause significant yield loss up to 30%. The identification of new Pm resistance genes will enrich the genetic diversity of wheat breeding for Pm resistance. Aegilops tauschii, the ancestor donor of sub-genome D of hexaploid wheat, is a gene pool of beneficial genes that can be easily transferred into wheat by production of synthetic hexaploid wheat followed by genetic recombination. We assessed the Pm resistance level of 35 Ae. tauschii accessions from different origins. Accession CIae8, exhibiting high resistance was used for gene mapping. Inheritance analysis using F2 and F2:3 populations derived from the cross between CIae8 and a Pm susceptible accession PI574467 revealed the Pm resistance was controlled by two independent recessive genes. Bulked segregate analysis using a 55 K SNP array revealed the polymorphic SNPs were concentrated distributed on 2DS (13.5-20 Mb) and 7DS (4.0-15.5 Mb). The Pm resistance loci were named as pmAet-2DS and pmAet-7DS, respectively. By recombinant screening, we narrowed the pmAet-2DS into a 370-kb interval flanked by markers CINAU-AE7800 (14.89 Mb) and CINAU-AE20 (15.26 Mb), mapped the pmAet-7DS to a 160-kb interval flanked by markers CINAU-AE58 (4.72 Mb) and CINAU-AE25 (4.88 Mb). The molecular markers closely linked with the resistance loci and the produced two synthesized hexaploid wheat (SHW) lines laid the foundation for the cloning of the two resistance loci and for their transferring into common wheat.