Genetic Analysis And QTL Mapping Of Whiteness And Color Traits In Wheat Flour

Flour color is an important trait in the assessment of flour quality for the production of many end products.Flour with high levels of yellow pigmentation is preferred for alkaline noodle production in many Asian countries noodles.Steamed bread,dry white noodle and dumpling made by the wheat flour are traditional food to Chinese,which request for the whiteness of flour.Flour whiteness and color behaves as a typical quantitative trait and controlled by multiple genes.Recently,the development of molecular markers such as RFLPs and SSRs,and their maps,have provided a powerful tool for elucidating the genetic bases of quantitatively inherited traits.In this study,Quantitative trait loci(QTLs) for flour whiteness(R457) and color in wheat were studied using a set of 168 doubled haploid lines, which derived from the cross 'Huapei 3'×'Yumai 57'.The DH and parents were evaluated for flour whiteness and color in three environments.A genetic map was constructed using 283 SSR and 22 EST-SSR markers.QTL analyses were performed using the software of QTLNetwork 2.0 based on the mixed linear model approach.The primary goal of the study described here was to detect QTLs with additive effects,epistatic effects,and QE intections for flour whiteness and color(a~*,b~* and L~*),which would be useful hould for manipulating the QTLs for flour whiteness and color by maker-assisted selection in wheat breeding programmes.The main results were as follows:1.Analysis of variance(ANOVA) and correlation were performed using the statistical software SPSS version 13.0(SPSS,Chicago,USA) program. The wide range of variation of the investigated traits and the normal phenotypic distributions indicated transgressive segregations,suggesting polygenic inheritance of flour whiteness,a~*,b~*,and L~*.Both absolute values of skewness and kurtosis were less than 1.0,indicating suitability of the data for QTL analysis.It was shown that the heritability of the flour whiteness,L~*, a~*,and b~* were 91.54%,56.49%,50.00%,and 98.33%,respectively.The number of segregating genes of those characteristics were 4.04,0.40,10.58 and 9.20.2.Twenty-two QTLs with additive effects and/or additive×environment effects were detected for flour whiteness and color in three environments, ranging from four to eight QTLs for each trait,which were distributed on 12 of the 21 chromosomes.Four QTLs were resolved for flour whiteness and mapped on chromosomes 1B,2D,4D,and 4D,which could account for 1.00%, 4.04%,2.56%,and 5.37%of the phenotypic variance,respectively.Three QTLs were detected for L~* and located on chromosomes 4D,5A,and 7D, which could explain 1.73%,1.17%,and 1.41%of the phenotypic variance, respectively.Six QTLs associated with a~* were detected on chromosomes 1B, 3B,5D,6A,6D,and 7D,which could account for 25.64%,3.94%,2.24%,2.49%,3.97%and 3.01%of the phenotypic variance,respectively.Among them,qa1B,linked to barc372 0.1 cM and could account for 25.64%of the phenotypic variation of a~* without any influence from the environments.So the qa1B could be used for wheat marker-assisted selection.Five QTLs were identified for b~* on chromosomes 2B,3D,4D,and 5A,which could explain 0.51%,2.95%,3.45%,and 4.30%of the phenotypic variance,respectively.3.Twenty-six pairs of QTLs with epistatic effects and/or epistasis×environment effects were detected for flour whiteness and color in three enveronments,ranging from two to ten QTLs for each trait.Two pairs of epistatic effects were detected for flour whiteness and located on chromosomes 1B-2D and 1D-6A.They explained 2.32%of the phenotypic variance.Four pairs of epistatic effects were identified for a~* and located on chromosomes 1A-7B,2A-4B,4D-6A,and 5B-7B.They explained the phenotypic variance ranging from 0.60%to 2.35%.Ten pairs of epistatic effects were resolved for b~* and located on chromosomes 3D-5B,1A-1B, 2A-3D,2B-7A,3A-5B,3D-4D,and 6B-7D.The total contribution often pairs of epistatic QTLs was 31.88%,so epistasis played a strong effect on b~*.Ten pairs of epistatic QTLs for L~* were resolved,which could explain the phenotypic variance ranging from 0.80%to 6.34%.