Mapping Of Resistance Loci To Powdery Mildew And Stripe Rust In Wheat Cultivar CH7034

Wheat?Triticum aestivum L.?is a staple crop in our country and even the world,and the loss of its yield and quality often caused by powdery mildew and stripe rust is occurred during the growth of wheat.It is of great significance to protect the high and stable yield of wheat by exploring the disease resistant genes and selecting the varieties with horizontal resistance and adult plant resistance?APR?.So far,more than 90 APR Pm/QPm and more than 110 APR Yr/QYr have been mapped in wheat,and the resistance mechanisms of several genes such as auxin/indole acetic acid?Aux/IAA?and nucleotide binding site?NBS?have been confirmed.However,most of the APR genes/QTL can not be effectively used in production because of their weak disease resistance or distant linkage markers.CH7034 is a wheat APR material selected by our laboratory and it resistance to both powdery mildew and stripe rust.In this study,we mapped the disease resistant QTL of CH7034 based on the DArT linkage map and the years of phenotype data of CH7034mapping population,and developed resistance sequence related SSR markers to construct the more densely populated map of QTL.The results obtained are as follows:1.Two thousand two hundred and eighty-eight TaNBS sequences were isolated from the wheat whole genome,of which 1386 had no expression data.Then 2203 SSR loci were detected from the scaffold sequences of TaNBS,and 1830 NRM?NBS-related microsatellite?markers were developed accordingly.In addition,eighty-four TaIAA sequences were isolated,twelve of which were not expressed.One hundred and thirty-one SSR loci were detected in TaIAA-scaffolds,and 124 IRM?IAA-related microsatellite?markers were developed accordingly.Three hundred and forty-two NRM markers and seven IRM markers from homologous group 2 of wheat were used to construct linkage map by CH7034×SY95-71 RILs F₉ population.Finally,sixty-nine NRM markers and two IRM markers,as well as 20 SSR markers and 16 DArT markers,were located on the map.Using these markers,the map-density of Yr69?2AS?,Pm51?2BL?and Pm43?2DL?are enhanced.2.Pedigree resistance identification results showed that the reactions after inoculating with Bgt isolates of CH7034 and its exogenous parent Xiaoyan7430 were similar?IT=0¹?,and its wheat parents were susceptible?IT=3⁴?;however,the results of cytological analysis showed that the 42 chromosomes of CH7034 do not contain exogenous signals,so it is uncertain whether the resistance of CH7034 comes from the exogenous chromosomes of Xiaoyan7430.Population resistance identification data showed that the resistance of CH7034 in both seedling and adult stage was controlled by multiple loci.Furthermore,a total length of 4191.9 cM,including 2347 DArT markers of high density molecular map was constructed using CH7034×SY95-71 RILs F₉ population,and then,two seedling-stage resistance loci?QPm.sac-2B.1 and QPm.sac-2B.2?were mapped,with the phenotypic variation explained?PVE?rates of 19.3²9.3%and9.8¹4.4%,respectively;moreover,five QPm in adult stage were also located,including QPm.sac-2A?13.4¹7.6%?,QPm.sac-2B.1?30.6³3.6%?,QPm.sac-2B.2?13.8¹9.1%?,QPm.sac-2D?14.1¹9.2%?andQPm.sac-3B?6.9⁷.5%?.QPm.sac-2B.1and QPm.sac-2B.2 were appeared during the whole growth period.We used four NRM markers?X2BL-NRM11,NRM12,NRM17 and NRM27?in the QPm.sac-2B.1 section to further locate it in the 672059683-717636972 physical section.Based on analysis of resistance source,resistance spectrum and linkage marker,we concluded that QPm.sac-2B.1 is not at the same locus as the currently named Pm6,Pm33 and Pm52 on wheat chromosome 2BL,while Pm51 may be the different coding gene at the same loci.3.The results of resistance identification showed that CH7034 was susceptible to three Pst races CYR32,CYR33 and CYR34?IT=3?in seedling stage,and it was nearly immune to mixed-Pst CYR32+33+34 in adult stage?IT=0;?.In CH7034×SY95-71 RILs population,the ratio of resistant lines and susceptible lines did not conform to the expected Mendel distribution value 1:1,indicating that the APR of CH7034 was controlled by QTL.Using molecular map and three years-resistance identification data of RILs,six APR-QYr were located from five wheat chromosomes.Among them QYr.sac-6A showed the highest PVE rate?25.0-26.5%?,and the rest were QYr.sac-1B.1?10.9-13.1%?,QYr.sac-1B.2?5.8-8.6%?,QYr.sac-2A?6.7-10.7%?,QYr.sac-7A?6.7%?and QYr.sac-7B?5.1-9.8%?.In the region of QYr.sac-6A,one IRM marker?IRM108?and 10 developed SSR markers were used to further locate it in the 606983357-608313911 physical section.Through analysis of resistance sources,resistance types and linkage markers,we concluded that QYr.sac-6A is different from YrXY9323,QYr.cim-6AL,QYr.cimmyt-6AL and QYr.cim2-6AL that located on chromosome 6AL,but Q6A and QYr.sac-6A may on the same locus.In summary,CH7034 is a new APR wheat material which has excellent resistance to powdery mildew and stripe rust,and it carrying two ASR-QPm,three APR-QPm and six APR-QYr.QYr.sac-6A is the APR-QYr of the largest PVE value on chromosome 6A at present,and SSR markers were developed and used to further map it in a physical section of 1.3Mbp accurately.This study provides a new APR source for wheat breeding,explores several QTL with high PVE value and stable resistance such as QPm.sac-2B.1 and QYr.sac-6A,constructs the more densely linkage map using NRM markers and IRM markers,and obtains the markers closely linked to resistant loci and can be used for PCR identification.