Molecular Characterization Of Genes For Resistance To Powdery Mildew PmQ And Stripe Rust Yr041133 In Wheats

Wheat powdery mildew?Blumeria graminis f.sp.tritici?DC.?Speer,Bgt?and stripe rust?Puccinia striiformis Westend.f.sp.tritici Eriks,Pst?are the major fungal diseases in China,which have seriously impacted on wheat production.The discovery of new resistance genes against powdery mildew?Pm?and stripe rust?Yr?is important in breeding for resistant wheat varieties to reduce the deleterious effects of these diseases.In this study,the genetic populations were conducted by the crossed of Xinjiang wheat landrace Qingxinmai?resistant to powdery mildew and stripe rust resistance?and Qinghai wheat line041133?susceptible to powdery mildew and resistance to stripe rust?.The BSR-Seq was used to characterize the Pm gene in Qingxinmai and the Yr gene in wheat line 041133 from Qinghai.The major findings are described below:1.Qinxinmai was resistant?IT 0-2?to 12 out of 23 Bgt isolates collected from different wheat fields in China.Qingxinmai was crossed to the powdery mildew susceptible wheat line 041133 to produce F₁,F₂,and F_2:3 populations.The genetic analysis using the Bgt1 isolate from Shandong province demonstrated that a single recessive gene,PmQ,conferred the seedling resistance to isolate Bgt1 in Qingxinmai.2.Line 041133 was resistant?IT 0;?to 11 out of 21 Pst races.Using Pst race CY34 to inoculate the F₁,F₂,and F₅ populations of Qingxinmai×041133 cross,resistance of 041133 to stripe rust was controlled by a single dominant gene,designated Yr041133.3.Bulked segregant analysis-RNA-Seq?BSR-Seq?was performed on the bulked homozygous resistant and susceptible F_2:3 families,which detected 53 candidate single nucleotide polymorphism?SNP?variants.Based on the physical positions of the candidate SNP variants,PmQ was located in a genomic interval?710-750 Mb?on chromosome 2BL.Based on the flanking sequences of the candidate SNPs extracted from the Chinese Spring reference genome,PmQ was placed in a 20.3 Mb physical interval?710-730 Mb?.A total of 485 simple sequence repears?SSR?markers were designed on the basis of the genome sequences of the target genomic interval.Six polymorphic SSR markers,together with nine markers that were linked to the known genes for powdery mildew resistance on chromosome arm 2BL,were used to construct a genetic linkage map for PmQ.This gene was placed in a 1.4 cM genetic interval between markers Xicsq405 and WGGBH913 corresponding to 4.3 Mb physical region in the Chinese Spring reference genome.PmQ differed from most of the other Pm genes identified on chromosome arm 2BL based on its position and/or origin.However,PmQ and Pm63 from an Iranian common wheat landrace PI 628024 were located in a similar genomic region,so they may be allelic.4.Using the BSR-Seq technology,Yr041133 was localized in a genetic interval between markers Xicst79 and Xicst162 on chromosome 7BL,with genetic distances of 2.0 cM and 1.3 cM,respectively.This genetic region corresponded to a 3.3 Mb physical interval?607.2-610.5 Mb?of the Chinese Spring reference genome.According to unique physical location,Yr041133 differed from other known Yr genes on 7BL,and is regarded as a new Yr gene.