| Common wheat(Triticum aestivum L.,2n=6x=42,AABBDD)is one of the most important food crops in China.Aegilops tauschii Coss(2n=2x=14,DD),as D genome donor of common wheat,with excellent properties,is regarded as one secondary germplasm resources for wheat genetic improvement.Synthetic hexaploid wheat(2n=6x=42,AABBDD)has been used as a bridge to transfer elite genes such as high yield from Ae.tauschii to common wheat.QTLs for early biomass and yield-related traits of Ae.tauschii were mapped under synthetic hexaploid wheat genetic background by SNP marker,in order to dig its excellent genes for wheat marker-assisted breeding.In order to dissect agronomic traits from Ae.tauschii,we developed a set of recombinant inbred lines(RILs)derived from the cross Syn79 x Syn80 which genetic recombination only on D genome at the hexaploid level.The AB genome of Syn79 and Syn80 was from the same durum donor DOY1,while their D genomes were from two different Ae.tauschii accessions,AT333 and AT428.Early biomass and yield-related traits of RILs and their parents were investigated under five different environments in three consecutive years from 2017 to 2019 at two different station Guang-Han and Cang-Shan.The main results were described as follows:1.The RIL population and their parents Syn79 and Syn80 were used to construct the genetic linkage map on D genome.For A,B and D genome,a total of 13947 SNPs were scanned to check the genotype of RIL population and their parents.And the results showed that almost all the SNP markers on AB genome had no polymorphism between two parents.3480 SNP makers were scanned on D genome,153 markers had polymorphism between two parents,and distributed unequally on the seven chromosomes of the D genome.The number of polymorphic SNP markers on chromosomes of D genome were as follows: 7D(34)> 1D(30)> 5D(25)>4D(21)> 2D(20)> 6D(15)> 3D(8).The whole genetic map covered over 803.84 c M on D genome with an average distance between adjacent markers was 5.25 c M,the average distance between two adjacent markers ranged from 2.67 c M to6.93 c M.The coverage length of 7 chromosome maps on D genome was significantly different: 7D(214.50 c M)>1D(127.58 c M)? 4D(145.52 c M)? 5D(135.72 c M)>2D(69.22 c M)? 6D(89.95 c M)>3D(21.35 c M).The genetic map was useful to explore elite genes derived from Ae.tauschii AT428 under genetic background of synthetic hexapoid wheat.2.Five different field trials were conducted at two locations over 3 years to evaluate early biomass related traits of the RIL population and their parents Syn79 and Syn80,and detect quantitative trait loci(QTL)for four early biomass related traits,including early plant height(EPH),early tiller number(ETN),early shoot fresh weight(ESFW)and early shoot dry weight(ESDW)per plant.As determined by SNP markers,a total of eight QTLs was detected for the four early vigor traits,two genome regions on 1DS and 7D were detected stably to be association with early vigor,and exhibited pleiotropic effects on EPH,ETN,ESFW and ESDW.Four stable QTLs for QEph.saas-1DS,QEtn.saas-1DS,QEsfw.saas-1DS and QEsdw.saas-1DS were clustered in the region of 1DS from AX-94812958 to AX-110910133,and explained 7.92,15.34,9.64 and 10.15 % of phenotypic variation on average,respectively.QEph.saas-7D,QEtn.saas-7D,QEsfw.saas-7D and QEsdw.saas-7D were mapped in the interval of AX-109917900-AX-110605376 on 7D,explaining the 16.12,24.35,15.25 and 13.37 % of phenotypic variation on average,respectively.Moreover,the genomic regions on 1DS and 7D enhanced the early biomass by QTL alleles of the parent Syn80,which was from Ae.tauschii AT428.These findings suggest that the eight QTLs enhancing early vigor from Ae.tauschii can express stably under synthetic hexaploid wheat background and be used for wheat improvement.3.15 yield related traits,including grain yield per plant(GY),effective tiller per plant(ET),grains per spike(GPS),thousand grain weight(TGW),shoot dry weight per plant(SDW),plant height(PH),grain length(GL),grain width(GW),grain length-width ratio(GLWR),grain area(GA),grain circumference(GC),grain diameter(GD),grain roundness(GR),spike length(SL),total spikelet number per spike(TSS)were investigated on 5 trials.A total of 34 QTLs for 15 traits were detected in mature stage,which distributed on all 7chromosomes of D genome,and mostly distributed on 1D,5D and 7D,and expressed stably.QTLs on 1D and 7D could be detected in the five different environments.QTLs for GY,SDW,ET and PH were clustered in the region of 1D from AX-109911195 to AX-109908110,and explained from 9.64 % to 13.94 % of phenotypic variation,and the favor QTL alleles enhancing yield were from the parent Syn80,as originated from Ae.tauschii AT428.QTLs for TGW,GL and GC were clustered in the region of 1D from AX-109849585 to AX-182152161.The expression of GL and GC was more stable than TGW,which explained the phenotypic variation was higher than TGW.QTLs for GW,GA and GD were clustered in the region of 2D from AX-109075563 to AX-111220010.QTLs for GY,SDW,GPS,TSS and GA were clustered in the region of 5D from AX-94647797 to AX-89564905.QTLs for TGW,GPS,SL and SDW were clustered in the other region of 5D from AX-94840001 to AX-95246226.QTLs for GY,SDW,ET,PH,SL and TSS were clustered in the region of 7D from AX-109917900 to AX-110605376.QTLs for yield-related traits on 1D,2D,5D and 7D derived from Syn80,and expressed stably,and be used for wheat improvement.4.Early biomass and yield related traits of the RIL population and their parents Syn79 and Syn80 were compared,the results showed that GY were significant positive related with ESFW,ESDW,ETN and EPH.ETN showed significant positive related with ET,EPH was significant positive related with PH.QTLs for early biomass was significant positive related with QTLs for yield related traits in mature.The intervals of QTLs for early biomass was overlapped with QTL intervals for yield related traits in mature,the main QTLs for early biomass and yield related traits enhanced their traits by the same parent.This is the genetic basis of the positive relationship between early biomass and yield related traits.In conclusion,this study mapped QTLs from Ae.tauschii enhancing early biomass and yield-related traits in a hexaploid background,dissected the genetic basis of positive relationship between early biomass and yield-related traits,and demonstrated that the QTLs from Ae.tauschii could be expressed stably in synthetic hexaploid wheat and be used for wheat improvement. |
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