| Maize(Zea mays ssp. mays) and its closest related wild progenitor, teosinte(Zea mays ssp. Parviglumis), differ strikingly in plant architecture and ear morphology, the vast majority of these differences controlled by genetic factor. Elucidating the genetic basis of architecture of these differences in morphological between maize and teosinte, is benefit for us to understand the selected target trait and target sites during maize domestication improvement, and it has important theoretical significance to enrich our understanding of the process of maize domestication.In this study, we used maize inbred lines Zong3 as recurrent parent and a teosinte species K-67-20 as donor, through two times of backcrossing and seven times of selfing, we constructed backcross recombinant inbred lines(BC2-RILs) population; Using the 56 K SNP chips to genotype the 198 maize-teosinte BC2-RILs population. We maked phenotypic evaluation based on 13 important traits of the BC2-RILs, in which the phenotype data from field experiments containing three field trials during two years; Combining the genotype and phenotype data, we performed the QTL mapping of important traits. The main results are as follows:1. We acquired 56 K SNP genotype data and 189 BC2-RILs phenotype data. Through strict quality control analysis, we obtain a high quality of 18777 SNP markers and constructed a high-density bin-map covering the whole genome which containing 1206 bins. The length of entire genetic map is 3151.9 cM, and the single bin average genetic distance is 2.61 cM, and the average physical length is 1.9 Mb. Background recovery rate of BC2-RILs is between 60.11% to 99.43%, and the average background recovery rate is 83.72%.2. Phenotype investigation of 13 important traits in three field trials during two years. We found that Maize-Teosinte BC2-RILs population presents rich genetic diversity, the heritability of different traits ranged from 72.98% to 90.97%. Correlation analysis found that different traits had complex relationships. Among them, plant height positively correlated with length of tassel and ear heigh, leaf width positively correlated with and ear height diameter of stem. In addition, a significant positive correlation between diameter of ear, kernel rows number and kernel number per row.3. QTL analysis of 13 traits. 243 QTLs were detected, distributed on all 10 chromosomes of maize, and most QTLs detected on chromosome 3. The number of QTL detected existed large differences between the different traits. The number of ear diameter QTLs is 33, larger than any others, a single QTL could explain the phenotypic variation between 2.68 % to 18.12%, among them, 72.73% of the QTL explaining phenotypic variation is less than 5%, indicating the trait may be controlled by several minor genes; The QTL number of total number of ears per plant is 21, a single QTL could explain phenotypic variation ranged from 2.64% to 31%, and seven of them were more than 15%. The remaining QTL explaining phenotypic variation is less than 10%, indicating the number of ear mainly controlled by several major genes.4. We detected eleven QTL regions which control multiple traits, and 70 QTLs that stably existed in multiple environments, these areas were proposed to be important on the chromosome. Compared with previous studies, we detected 82 co-localization QTLs(33.74%), which 58 QTLs(23.87%) associated with domestication sites and 24 QTLs(9.88%) associated with improvement loci. These sites can be used as targets of QTL fine mapping, clone, domestication and any other further researches. |
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