Molecular Mapping Of Stripe Rust Resistance Genes In Common Wheat

Stripe rust,caused by Puccinia striiformis f.sp.tritici?Pst?,is an important disease of wheat around the world.Compared with chemical control,breeding for resistant cultivars has been a relatively successful strategy to curtail the influence of stripe rust on agricultural productivity.New pathogen races quickly emerge frequently and become prevalent by the using of unique rust resistance in wide cultivation,which results in the resistance breakdown of wheat cultivars and huge yield loss.The exploration of resistant materials,identification of new resistance genes and tightly linked molecular markers is the basis of diversification of the resistance genetic.In the present study,we constructed several genetic populations based on three resistant wheat cultivars,in combination with bulked segregant analysis?BSA?,SSR markers,Wheat iSelect 90 K SNP array and KASP to map stripe rust resistance genes.The main results are as follows:1.Genetic analysis of F₂ and F₂:3 populations from an Avocet S/Jimai 22 cross indicated that stripe rust resistance in Jimai 22 was conferred by a single dominant gene,tentatively designated YrJ22.A total of 377 F₂ plants and 117 F₂:3 lines were tested with Chinese Pst race CYR32 and genotyped with simple sequence repeat?SSR?,and single nucleotide polymorphism?SNP?markers.A linkage map was constructed with five SSR and two SNP markers.Xwmc658 and wsnp_Ex_c10555₁7235832 flanked YrJ22 at genetic distances of 1.0 cM and 7.3 cM,proximally and distally,respectively.The chromosomal location was confirmed using Chinese Spring nulli-tetrasomic,ditelosomic and deletion lines.Seedling reactions to 21 Pst races demonstrated differences in specificity between YrJ22 and other resistance genes on chromosome 2AL,indicating that YrJ22 is likely to be a new wheat stripe rust resistance gene.2.Chinese landrace Baidatou showed high resistance against many Chinese Pst races both at seedling and adult-plant stages.To identify stripe rust resistance gene in Baidatou,a cross was made between Baidatou and Huixianhong that is susceptible to all known Chinese Pst races.Genetic analysis of the F₁,F₂,F₂:3 and BC1 populations indicated that resistance to Pst race CYR32 was conferred by a single dominant gene,temporarily named as YrBdt.Molecular marker analysis placed the gene on wheat chromosome bin 1AL1-0.17-0.61.Five SSR markers Xbarc28,Xwmc120,Xbarc350,Xgwm135 and Xbarc209,and two SNPs IACX1592 and RAC875_c33300₁41 were linked with the resistance gene.Respectively,two flanking markers were Xgwm135 and Xbarc209 with genetic distances of 0.9 and 2.2 cM from YrBdt.Based on the chromosomal location and pedigree analysis,YrBdt is likely to be a new stripe rust resistance gene.The resistance gene and flanking markers could be used in wheat breeding for improvement of stripe rust resistance.3.Seedling test showed that Chinese landrace Wudubaijianer conferred a high level of resistance to a range of Pst races.Wudubaijianer was crossed to Huixianhong to establish F₁,F₂ and F₃ populations,which were inoculated by the prevalent Pst race CYR32.Seedling resistance analysis exhibited that the stripe rust resistance in Wudubaijianer was conferred by a dominant and a recessive gene,tentatively designated YrWD.Of the 759 SSR markers tested,two?Xbarc236 and Xwmc468,with genetic distances of 17.7 and 47.2 cM from YrWd?showed stable polymorphisms between the parents and contrasting bulks.