| Wheat is one of the most important crops in the world.Stripe rust（yellow rust）caused by Puccinia striiformis Westend.f.sp.tritici Erikss.（Pst）,is one of the most destructive diseases of wheat.In China,stripe rust is the major disease in causing yield and quality losses.The most effective and economical method to decrease stripe rust is to get rational utilization of stripe rust resistance genes and breed wheat accessions resistant to stripe rust.So,the discovery of novel resistance genes to stripe rust and their application in wheat breeding has always been the focus of wheat research in China.Wheat landraces have been developed and domesticated for a long time locally,after artificial and natural filtering,the landraces were widely adapted to the highly varied ecological and geographical environments under high stripe rust pressure,with important target traits of modern wheat genetic improvement such as resistance to insects/cold/diseases.In nearly 10 years,resistance phenotype of stripe rust identified in the field found that Chinese wheat landrace Guangtoumai（GTM）showed stable adult-plant resistance（APR）to the physiological subspecies and pathogenic groups of stripe rust.The objective of this research was to identify quantitative trait loci/locus（QTL）for adult-plant resistance to stripe rust in GTM.A set of 339 F5:7recombinant inbred lines（RILs）was developed from a cross between GTM and Avocet S by single particle transfer method,and these lines were used to genetic analysis and molecular mapping.Furthermore,the QTL mapping of APR to stripe rust was carried out by using high density genetic linkage map constructed by Wheat55K SNP arrays and combined with phenotype of APR to stripe rust.The following main research results were obtained:1.According to the identification of current predominant Pst races at the seedling stage,the stripe rust response of GTM was susceptible to CYR32 and CYR33 and rated with infection type 7.While the identification results of resistance to stripe rust in adult-plant stage revealed that GTM has high resistance to mixture of prevalent Pst races and rated with infection type 1～2 in multiple environments,final disease severity（FDS）was 1.67～8.33%,indicating that GTM had broad spectrum resistance to stripe rust.The phenotypic analysis of stripe rust in parents and RILs were carried out under three artificial inoculation environments.The distribution of disease severity frequency showed continuous,therefore the APR to stripe rust in GTM was controlled by quantitative trait loci（QTL）.2.Wheat55K SNP array was used to construct the high density marker genetic map,A total of 985 SNP markers were involved,covering 21 chromosomes of wheat,with a total length of 2405.57 c M and an average distance between two markers of 2.44c M.3.The ICIM method was used to analyze the QTL of RILs with the disease severity and Wheat55K SNP array,two QTLs controlling adult plant resistance to stripe rust were obtained,which were temporarily named QYr.GTM-2AS and QYr.GTM-5DL.Among them,QYr.GTM-2AS is located on the short arm of chromosome 2A,and mapped in a 4.5 c M genetic interval flanked by SNP markers AX-111191799 and AX-109998719,explaining 9.27～14.98%of the phenotypic variation（PVE）.QYr.GTM-5DL is located on the long arm of chromosome 5D,and mapped in a 2.75 c M genetic interval flanked by SNP markers AX-109855976 and AX-111512534,explaining19.17～34.80%of the phenotypic variation.Based on consistent map,genetic and physical map of stripe rust resistance genes,these two QTLs are likely novel APR genes.Genetic effect analysis showed that the disease severity of stripe rust in lines with QYr.GTM-2AS and QYr.GTM-5DL can be significantly decreased.4.Haplotype analysis of the major effect of resistance QTL QYr.GTM-5DL was carried out in 244 Sichuan wheat germplasms,result revealed that three wheat germplasms with the same resistance allele with GTM displayed enhanced levels of APR to stripe rust,and their average disease severity was 15.50%,which lower than average disease severity of wheat germplasms in other five haplotypes.5.Five specific dCAPS markers were converted from SNP markers which closely linked with QYr.GTM-5DL,and detected in 48 Sichuan wheat cultivars,result showed that d CAPS markers d CAPS-5722 can specifically detect the presence of QYr.GTM-5DL in wheat germplasms,which could be used for molecular marker-assisted selection of QYr.GTM-5DL. |
