Genetic Analysis And Molecular Mapping Of Resistance Genes To Stripe Rust And Powdery Mildew In Three Wheat Varieties

Stripe rust and powdery mildew are the two important diseases of wheat.The most effective,economical and environmentally-friendly way to control diseases is to plant disease-resistant varieties.However,the application of a single resistance gene will lead to the emergence of new epidemic races,so that the resistance of varieties would be lost.Therefore,it is urgent to identify and mapping new resistance genes in wheat varieties?lines?for pyramiding different types of resistance genes to produce high-level durable disease resistant varieties for sustainable control of stripe rust and powdery mildew.The wheat landrace Wudubaijian have been widely grown for severy years in the stripe rust epidemics region,and it still have resistance to all stripe rust race.The wheat-Leymus mollis introgression line M8664-3 exhibits all-stage resistance to Chinese stripe rust races.Wheat variety‘Tianxuan 45'exhibits all-stage resistance to powdery mildew.The objectives of this study were to identify and map the gene?s?for resistance in these cultivars?lines?using genetic analysis and molecular markers.The main results gained are as follows:1.Wudubaijian exhibits adult-plant resistance to Chinese stripe rust races but susceptible in seedling stage.The survey of the relative area under disease progress curve?rAUDPC?of Mingxian169/Wudubaijian F_2:3 lines in the four environments of Yangling and Tianshui in2015 and 2016 showed that the resistance in Wudubaijian was controlled by more than one Quantitative trait loci?QTL?.Combined with phenotypic data and molecular markers,we found two QTLs with high phenotypic variation explained?PVE?in two calculation methods.QYrwdbj.nwafu-5A with the phenotypic variance of 15.02%-40.26%,is located between5AS1-0.40-0.75 and 5AS3-0.75-0.98 of chromosome 5AS;QYrwdbj.nwafu-2B.1 with the phenotypic variance of 9.54-10.40%,is located in the bin C-2BS1-0.53 of chromosome2BS.Through molecular detection and epistasis analysis,QYrwdbj.nwafu-5A may be a new major QTL that can be used in conjunction with other sites.This model can provide new ideas for the realization of durable resistance in breeding design.The flanking markers AX-111500211 and AX-110411572 linked to QYrwdbj.nwafu-2B.1 and the flanking markers AX-110458796,AX-109621625 and AX-111568277 linked to QYrwdbj.nwafu-5A can also be used in molecular marker assisted breeding.2.Genetic analysis of stripe rust resistance was performed by crossing M8664-3 with the susceptible line Mingxian169.Analysis of the disease resistance of F₂ and F_2:3 populations revealed that its resistance to Chinese stripe rust race 33?CYR33?is controlled by a single dominant gene,temporarily designated as YrM8664-3.Genetic and physical mapping showed that YrM8664-3 is located in bin 4AL13-0.59-0.66 close to 4AL12-0.43-0.59 on chromosome4AL and is flanked by SNP markers AX-111655681 and AX-109496237 with genetic distances of 5.3 and 2.3 cM,respectively.Resistance spectrum and position analyses indicated that YrM8664-3 may be a novel gene.Molecular detection using the markers linked to YrM8664-3 with wheat varieties commonly cultivated and wheat-L.mollis derived lines showed that YrM8664-3 is also present in other wheat-L.mollis introgression lines,but absent in commercial common wheat cultivars.YrM8664-3 is thus a potentially valuable source of stripe rust resistance for breeding.3.Wheat variety“Tianxuan 45”exhibits resistance to the highly virulent Bgt isolate HY5.Genetic analysis of the F₂ and F_2:3 populations of a Mingxian169/Tianxuan 45 cross revealed that its resistance to HY5 is controlled by a single recessive gene,temporarily designated as PmTx45.A Manhattan plot was used to show the relative frequency distribution of single nucleotide polymorphisms?SNP?to rapidly localize the associated genes.This microarray-based bulked segregant analysis?BSA?largely improved traditional analytical methods.PmTx45 is located in bin 4BL5-0.86-1.00 and is flanked by SNP marker AX-110673642 and Intron length polymorphism?ILP?marker ILP-4B01G269900 with genetic distances of 3.0 and 2.6 cM,respectively.Molecular detection using the markers linked to PmTx45 with wheat cultivars showed that the presence of PmTx45 in commercial wheat cultivar is rare.Resistance spectrum and position analyses indicated that PmTx45 may be a novel recessive gene with moderate powdery mildew resistance.This new method to analyze microarray-based BSA is feasible and valuable,and PmTx45 have the potential application for marker-assisted breeding.