Construction Of Chromosome Frsgment Substitution Lines Of Wheat-Aegilops Tauschii And QTL Mapping Of Grain Traits

Aegilops tauschii Cosson(2n=2x=14,DD)was a D genomic donor of common hexaploid wheat and contains beneficial genes such as high yield,disease resistance and insect resistance,its genetic variation was far richer than that of wheat D genome.The excellent genes of Ae.tauschii can be introduced into common wheat by means of distant hybridization and synthetic methods,which provided the basis for enriching the genetic basis of wheat and creating good germplasm resources.In this study,we used zhoumai 18 and Ae.tauschii T015 for hybridization,and colchicine induced doubling,then back with zhoumai 18 once,selfing one time to obtain the BC1F1 substitution line containing the chromosome fragments of Ae.tauschii.The population was followed by a row of six times to construct a BC1F7 substitutional group with zhoumai 18 as a genetic background.The genotype data of SSR molecular marker and QTL Ici Mapping V4.0 software were used to construct the genetic linkage map of D genome according to the phenotypic data of the substitution line.Thousands of grain weight,grain weight per spike,grain length,grain size,grain circumference,and grain length-width ratio were used for QTL mapping.The following results were obtained:In this study,261 pairs of SSR molecular marker primers were synthesized from the Grain Genes 2.0 database.38 pairs were synthesized on 1D,44 pairs were synthesized on 2D,35 pairs were synthesized on 3D,31 pairs were synthesized on 4D,32 pairs were synthesized on 5D,41 pairs were synthesized on 6D,40 pairs were synthesized on 7D.A total of 168 pairs of polymorphic primers were detected to detect the polymorphism of zhoumai 18 and Ae.tauschii T015,and the detection rate of polymorphic primers was IV 64.37%.A total of 66 pairs of polymorphic primers were detected by using the 168 pairs of primers for further detection of 37 isolates.There were 8 polymorphic markers on the 1D,3D and 5D chromosomes,and 12,11,10 and 9 polymorphic markers were detected on 2D,4D,6D and 7D chromosomes respectively,the polymorphism of the primers was 39.29%.Eleven QTL loci were detected in the QTL mapping results of BC1F7 substitution line in Huixian,which were distributed on 2D,3D and 7D chromosomes respectively.Only one QTL locus associated with 1000-grain weight is located on the 2D chromosome,three QTLs related to grain weight per spike,distributed on 2D,3D and 7D chromosomes,there were three QTLs which control grain length were mapped on 2D,3D and 7D chromosomes,there was one QTLs controlling the grain width on the 3D chromosome,only one QTL associated with the grain circumference are located on the 2D chromosome,there were two QTLs related to the aspect ratio of grain,which were distributed on 2D and 7D chromosomes.Five QTLs were mapped on 2D chromosomes,which were related to five traits such as 1000-grain weight,grain weight per spike,grain length,grain circumference and grain aspect ratio,three loci were mapped on the 3D chromosome,and per locu was associated with three traits such as grain weight,grain aspect ratio,3 QTLs controlling grain weight,grain length and grain length ratio on 7D chromosome.On 2D chromosome,the interval Xcfd53-Xgwm296 was detected twice,which was related to two grain traits such as 1000-grain weight,grain length-width ratio;the interval Xbarc95-Xcfd53 was detected twice,correlated with grain length and grain circumference;in the QTL mapping analysis related to spike weight,the interval Xcfd51-Xbarc95 was detected.There were eight QTL locis detected in QTL mapping results of Zhongmou BC1F7 population,which were distributed on 2D,5D and 7D chromosomes.Two QTLs associated with 1000-grain weight were located on 2D,5D;one QTL associated with grain weight per spike,distributed on 2D chromosome;one QTL that controls grain length was localized on 2D chromosomes;only one QTL controlling the grain width was located on 7D chromosome;the QTL associated with the grain circumference was located on 2D chromosome;there were two QTLs related to the composite traits of grain length and width,which were distributed on 2D and 7D chromosomes.The interval Xcfd53-Xgwm296 on 2D chromosome was related to two traits such as 1000-grain weight and grain weight per panicle.The interval Xgwm296-Xwmc181 b on 2D chromosome was related to the three traits such as grain length,grain circumference and grain length-width ratio.The range of Xcfd8-Xwmc289 b on 5D chromosome was correlated with the 1000-grain weight.There were two QTLs on 7D,which were located at the interval Xwmc473c-Xbarc214 and the interval Xcfd66-Xgpw1142 b,controlling grain width and grain length-width ratio respectively.Based on the comparative analysis of QTL mapping results of BC1F7 populations in Huixian and Zhongmou,QTLs related to five traits such as 1000-grain weight,grain weight per panicle,grain length,grain circumference,and grain length-width ratio,which were found on 2D chromosome.The interval Xcfd53-Xgwm296 on 2D was detected correlating with 1000-grain weight in both two environments,indicating that there was a QTL locus to control 1000-grain weight on 2D.In the two environments,the interval Xcfd66-Xgpw1142 b on 7D was detected when the QTL mapping analysis was carried out with grain length-width ratio,indicating that there was a probability of controlling the QTLs for grain length-width ratio in the interval.