Identification Of A Major Effect QTL Conferring Adult Plant Resistance To Stripe Rust In Wheat Cultivar Yaco"S" And Detection Of Fhb1 In Wheat

Stripe or yellow rust,caused by Puccinia striiformis Westend.f.sp.tritici Erikss.?Pst?,are important constraints to common wheat production in most parts of the world where the cool temperature prevails and affects wheat yield and quality.Although stripe rust can be controlled by spraying chemical fungicides,on account of using of fungicides neither cost effective nor environmentally safe,the best strategy to contro l the disease is to use adequate level of resistant cultivars.Race-specific resistance gene underlying the gene-for-gene hypothesis are highly specific and often elicit rapid and localized plant cell death,known as a hypersensitive response,consequently,the growth of invading pathogen is strongly inhibited or completely stopped.Directional selection occurs when a race-specific resistance gene becomes widely distributed over a large geographical area of wheat.This leads to the establishment of some virulent mutants that have lost the function of elicitor/effector.Adult-plant resistance?APR?with sufficient high levels of durability resistance has been obtained by several QTL?genes?.These QTLs illustrate a genetic diversity for this trait,although some of them maybe redundant.These QTLs show different sizes of effect.The term“major QTL”is often used to indicate the QTL that has large effect.Fhb1 is existed in many Chinese germplasms such as Sumai 3,Fanshanxiaomai and Wangshuibai,which is a major effect QTL conferring resistance to fungal spread within spikes.Fhb1 existed in candidate cultivar is still obscure,it is worthy to take a identification technology system for the analysis of resistance gene Fhb1 to Fusarium Head Blight,which could be used for application and promotion of the cultivars.Wheat cultivar Yaco"S"showed a high level of APR to stripe rust in the field from2008 to 2014.The objective of this study was to detect the major quantitative trait loci?QTL?for APR to stripe rust in Yaco"S".One hundred and eighty-four F_2:3:3 lines were developed from a cross between Yaco"S"and susceptible cultivar Mingxian 169.Illumina 90K and660K SNP?single nucleotide polymorphism?chips were implemented to bulked pools and their parents to identify SNPs associated with the major QTL.The results are as follow:1.SNP chips were used to screen polymorphic markers between bulked pools and parents.A high-density linkage map was constructed using simple sequence repeat?SSR?and SNP markers.The F₂ and F_2:3:3 lines were evaluated at Yangling?Shaanxi province?and at Tianshui?Gansu province?.The infection type and disease severity?DS?were recorded for the QTL analysis.2.Inclusive composite interval mapping?ICIM?detected a major effect QTL Qyryac.nwafu-2BS conferring stable resistance to stripe rust in all tested environments.Qyryac.nwafu-2BS were mapped to a 1.3 cM interval and explained 17.3-51.9%of the phenotypic variances.Compared with stripe rust resistance genes previously mapped to chromosome 2B revealed that Qyryac.nwafu-2BS are likely a new APR gene for resistance to stripe rust.Combining SNP iSelect assay and kompetitive allele specific PCR?KASP?technology,the APR gene could be rapidly and accurately mapped and could be useful for improving stripe rust resistance and marker-assisted selection in wheat breeding.3.One hundred and ninety wheat materials were screened by a STS marker and KASP marker,seven of them showed the same genotypic as Sumai 3.This suggested that selection based on these markers would be effective in predicting resistance status of unknown genotypes.