Genome-wide Association Study For Kernel Hardness And Flour Color Of Wheat (Triticum Aestivum L.)

Wheat?Triticum aestivum L.?is widely cultivated in all parts of the world,whose production is only second to corn.The wheat in our contury is mainly of medium hardness,but the hard and soft wheat are less,so we need to import every year.Kernel hardness not only affects the processing quality of food,but also affects the processing quality of flour.Flour color can affect the color and appearance of cooking food.In order to increase the whiteness,people added a lot of flour brighteners?BPO?,which affected our health.By analyzing kernel hardness,hardness index,flour color and other related traits,the research contains the following three aims: First,to identify factors that affected the kernel hardness and flour color;Second,to find the gene loci of controlling kernel hardness to provide theoretical basis for wheat quality improvement;Third,to meet the need of high-quality wheat.The material of the research consisted of 205 natural population in three environments.The kernel hardness,hardness index,flour color and its related traits were tested,which contained phenotype analysis,correlation analysis and related analysis.The main results are as follows:1.Phenotype analysis The kernel hardness and hardness index of wheat are mostly medium hardness in three environments.Through the phenotype analysis,the range of hardness is greater.The coefficients of phenotype of kernel hardness and hardness index were respectively 27.29%-31.80% and 14.45%-15.60%.This research on the kernel hardness,hardness index had abundant genetic variation,and had great potential in variety improvement.In flour color,the range of the flour color brightness?L*value?was largest.The highest variation coefficient was redness?a*value?,as high as 15.06%.The variation coefficients of the brightness?L*value?and yellowness?b*value?were respectively 12.42% and 8.56%.2.Correlation analysis The kernel hardness was extremely significant positively correlated with hardness index,and the coefficient was 0.777**.The protein content was extremely significant positively correlated with the kernel hardness,and the coefficient was 0.081**.The test weight and kernel hardness were extremely significant negatively correlated,the coefficient was 0.145**.The test weight,diameter,amylopectin,amylose,and total starch were positively correlated with hardness,but not significant.The powder yield,center powder,wet gluten extremely positively correlated with hardness index,and the coefficient were 0.1977**,0.407** and 0.107**.The bran extremely significant negatively correlated with hardness index,and the coefficient was 0.361**.The gluten index,dry gluten and hardness index were positively correlated,but not significant.The brightness of flour color?L*value?was extremely significant negatively correlated with kernel hardness,and the coefficient was-0.148**.The redness?a*value?and yellowness?b*value?were extremely significant positively correlated with kernel hardness,and the coefficients were 0.152** and 0.374**.3.Genome-wide association study 128 MTAs of kernel hardness were detected on 1A,1D,2B,2D,3B,4A,5A,5B,5D,6A,7A and 7B chromosomes.Among them,the MTA of BS00000020₅1 with the highest contribution rate,explained 15.91% phenotype variation.The MTAs also were identified on 3B and 7B,whose contribution rates were higher.Of these,the marker of Bob White_c40042₃93 on 7B chromosome would be the new genetic site.Detected 29 MTAs of hardness index,were distributed on 1A,1B,1D,2A,2B,3 B,5B,5D,6A,6B and 7B chromosomes.Among them,the marker of BS00000020₅1 on 5D chromosome,whose contribution rate was highest,which can explain the phenotype variation rate was 10.95%.Also detected the marker of Bob White_c40042₃93 on 7 B chromosome.9 MTAs were detected for brightness of flour color?L* value?,which distributed on 3A,3D,5A,5B and 6B chromosomes.Among them,the marker of wsnp_Ex_c58091₅9534826 on 5B chromosome,whose contribution rate was highest,explained 7.52% phenotype variation.29 MTAs were detected for redness?a*value?,which distributed on 1A,1B,2 A,2B,2D,4A,5B and 7D chromosomes.Among them,the marker of Kukri_c14239₁995 on chromosome 1B,whose contribution rate was highest,explained the 12.43% of phenotype variation.12 MTAs were detected for yellowness?b* value?,which located on 1D,2D and 3B,5A and 5B,6A and 7B chromosomes.Among them,the marker of RFL_Contig5314₁147 on chromosome 6A,whose contribution rate was highest,explained 7.17% phenotype variation.4.The selection of germplasm resources of wheat Examined 205 wheat germplasm resources,which consisted of 25 varieties?lines?of soft wheat,such as Xuzhong24,Fan7030,Sheng74,Zhaoshan15,Shannong11 etc.17 varieties?lines?of hard wheat were selected,such as Tainong19,Sheng62,Wan 38 and Jinan 17 etc.