Fine Mapping Of Wheat Stripe Rust Resistance Gene Yr59 And Molecular Marker-assisted Selection Breeding

Wheat stripe rust is a fungal disease caused by stripe rust fungus（Puccinia striiformis Westend.f.sp.tritici Erikss,Pst）,the persecution from this disease to wheat yield and quality is almost devastating.In China,the annual infection area of stripe rust is as much as million hectares,resulting in a loss of more than one million tons of production.At present,plant resistant wheat varieties to prevent stripe rust are the most efficacious and greener means.However,the continuous mutation of stripe rust pathogens and the large-scale planting of wheat varieties with single resistance have caused the resistance genes to be overcomed by new virulence race,resulting in resistant varieties lose their resistance.Therefore,the excavation and utilization of wheat stripe rust resistance genes is no less portentous to China’s wheat production and food security.Wheat PI 660061 contains high-temperature adult-plant resistance gene Yr59,the initial mapping genetic distance is 2.1c M,and the flanking markers are Xbarc32～Xwgp5175.On this basis,this study carried out fine mapping and screened out the candidate genes to this resistance gene;Meanwhile,Yr59 was introduced into four main varieties to screen wheat materials with excellent resistance and agronomic characters.The main conclusions are summarized below:1.Stripe rust responses were assessed to PI 660061,Mingxian 169 and Avocet S by using races CYR32,CYR33,and CYR34 in the greenhouse.In seedling stage,all varieties showed high susceptibility to three test races.In adult-plant stage,Mingxian 169 and Avocet S stay susceptible,while PI 660061 showed high level resistance,indicating that PI 660061 has adult-plant resistance.2.Genetic analysis was carried out on the field disease resistance investigation results of PI660061/Jinmai47 F₂ lines,indicating that the disease resistance of PI 660061 to stripe rust controlled by a pair of dominant genes,consistent with the previous research.3.Genotyping the parents PI 660061 and Jinmai 47 by 55K SNP gene chip.There were 25SNP markers in the initially mapping location,including 8 differential SNPs.These eight differential SNPs were developed into KASP markers.Then three parents,F₂ and F₆ RILs population were genotyped by using these eight markers.At last,five KASP markers linked to stripe rust resistance gene Yr59 were obtained.Among them,AX-108957944 and AX-109926256 reduced the location interval to 1.0 c M,0.54 c M and 0.46 c M away from Yr59respectively.4.Anchoring the flanking marker on the IWGSC Ref Seq v1.0.The physical region of the flanking segment was 27.5Kb.This segment contained five High confidence（HC）annotation genes and eight Low confidence（LC）annotation genes.One HC annotation gene contains a serine/threonine protein kinase disease resistance related domain.This candidate gene provides an important object for the cloning of Yr59.5.Used as male parent,PI 660061 was hybridized with Chinese main varieties Chuanmai 42,Jimai 22,Zhengmai 9023 and Xinmai 26 respectively,and then F₁（BC₁F₁）was continuous backcrossed with female parent.The obtained BC₂F₁ was mixed collection separately and planted in the experimental field until BC₂F₄.Taking high level stripe rust resistance,80-110cm plant height and multiple tiller and spikelet numbers as the standard,artificial screening was carried out in BC₂F₄,and 123 BC₂F₅ lines were screened.6.The parents,BC₂F₅ and BC₂F₆ lines were detected with markers linked to stripe rust resistance gene Yr59,and 109 lines were screened.The field agronomic characters（plant height,number of spikes,spike length,grain number per spike,1000-grain weight）of BC₂F₅and BC₂F₆ were investigated and recorded for two consecutive years.Combined with the results of molecular marker detection and the agronomic characters,16 lines were finally selected which successfully integrate the stripe rust resistance gene Yr59 and possess excellent agronomic characters.