152 Synthetic Wheat Yield-related Traits Genome-wide Association Study

Wheat(Triticum aestivum L.)is one of the major food crops in the world.With the decrease of cultivated land area and population growth in China,the problem of food security has become increasingly prominent,and it is very important to improve the potential of wheat yield.It is a new development trend in the field of wheat breeding to explore,innovate and utilize keystone species quality resources and seek a breakthrough in yield through distant hybridization.However,the existing genetic diversity basis of wheat has limited the yield breeding of wheat,and it is urgent to solve the serious problem of narrow genetic basis.In this study,152 synthetic wheat varieties(lines)newly introduced from CIMMYT were used as experimental materials,and the yield-related traits were counted.Using 55 K SNP marker data and based on population structure,the correlation analysis between yield traits and markers was carried out,and the significant points related to yield traits were detected and controlled,which provided a basis for wheat molecular marker-assisted selective breeding and fine positioning.The main research results are as follows:1.Statistical analysis of phenotypic traits showed that there were wide variations among the five traits,with the coefficient of variation ranging from3.33% to 22.79%.The minimum coefficient of variation of grain length was3.33% under BLUP and the maximum coefficient of variation of 1000-grain weight was 22.79% under Chengdu planting environment.Furthermore,the five yield-related traits are all distributed continuously,which accords with the trend of normal distribution.Correlation analysis showed that plant height was positively correlated with ear length and grain length,and 1000-grain weight was positively correlated with grain width.Analysis of variance of 3environments,plant height and spike length showed significant differences among genotypes.Joint variance analysis in three environments found that the phenotypes of plant height and spike length showed significant differences in genotype,environment and genotype environment interaction.It indicated that plant height and spike length were greatly influenced by genotype,interaction of environment and genotype.2.Genetic analysis of population structure showed that the population of synthetic wheat materials could be divided into three subgroups.It is mainly divided by parent tetraploid wheat(AABB)donor genome,while wild Aegilops tauschii(DD)genome has little contribution to the division of synthetic wheat population structure,the source of tetraploid durum wheat is an important reason for different subgroups.3.152 synthetic wheat varieties(lines)were scanned by using 55 K SNP chip,and 37916 effective SNPs were obtained.Among them,there are 14404,14566 and 8946 subgenomes in A,B and D,respectively.Subgenome B has the highest density(0.355 Mb/ marker),followed by subgenome A(0.362Mb/ marker),while subgenome D has the lowest marker density(0.441 Mb/marker).The 6A chromosome with the highest density contains 2394 markers with an average of 0.258 Mb/ marker,while the 4D chromosome with the lowest density contains 787 markers with an average of 0.647 Mb/ marker.4.Through genome-wide association study,173 significant SNPs(P ≤0.0001)were detected in four environments with BLUP value,which distributed on 21 chromosomes of wheat and could explain 9.28-34.70% of phenotypic variation.Among them,74 significant SNP markers were screened by BLUP value,10 were related to plant height,22 spike length,9grain length,25 grain width and 11 thousang grain weight.Four possible“one cause and multiple effects” markers were screened.AX-110055532 controlled ear length and grain length simultaneously,AX-108833851 controlled grain width and 1000-grain weight simultaneously,AX-108729778 controlled plant height and grain length simultaneously,and AX-111157142 controlled grain width and 1000-grain weight simultaneously.5.Analysis of the number of positive effect loci showed that the more positive effect loci in synthetic wheat population,the lower the average plant height,and the higher the spike length,grain length,grain width and1000-grain weight.6.The screened BLUP value is significantly about 3 Mb away from the genome,and its gene expression in stem,ear and grain is counted respectively.659 genes with high expression are selected and annotated.According to the annotation of rice genes,19 genes related to various traits with functional reports in rice are inquired.