Preliminary Dissection Of Genetic Basis Of Important Traits In Maize By Maize-teosinte Introgression Populations

Maize（Zea mays L.）is a widely grown crop worldwide,and cultivating excellent corn varieties plays an important role in maintaining national food security.At present,the basis of cultivated maize germplasm is relatively narrow,which gradually becomes the main obstacle for further improvement of maize.There are many unutilized excellent traits and excellent alleles in the wild relative of maize,teosinte,and its research and utilization will help to expand maize germplasm resources and provide excellent genetic resources for modern maize breeding and improvement.In this study,two BC₁F₆ populations were constructed by crossing,backcrossing,and multi-generation self-crossing,using Zheng58and two teosinte inbred lines,TIL11 and TIL14.The two introgressed populations were planted in three environments of Wuhan,Zibo and Sanya,the agronomic traits were investigated,and 3’RNA-seq technology was used to sequence the transcriptomes of each family,thus obtaining the phenotypes,genotypes and genome-wide expression data,combined with eQTL and WGCNA analysis to mine key candidate genes,to analyze the genetic basis of the variation of important agronomic traits in these two introgressed populations,and to identify excellent alleles,which are wild maize germplasm resources utilization provides reference,and ultimately provides excellent genes and germplasm resources for the genetic improvement of modern maize in my country.The main results are as follows:1.The nine important agronomic traits of the two introgressed populations were investigated in three environments.The results showed that there was a wide range of genetic diversity and large phenotypic variation among the families in the population.The distribution of genotypes is in line with the genetic characteristics of quantitative traits.The heritability of each trait was between 0.50-0.83,and there was a significant correlation between different traits.2.Genome-wide genotype and expression data were obtained for 142 families in the TIL11 population and 157 families in the TIL14 population.Based on the genotype data,the linkage map was constructed.The TIL11 introgressed population obtained a linkage map containing 1859 bin markers and full-length is 1642.82c M,the TIL14 introgressed population obtained a linkage map containing 1776 bin markers and full-length is1459.03c M,both of them showed good collinearity between linkage map and physical map.Based on the linkage map,the TIL11 introgressed population was mapped to 45 QTL loci,9 of which could be detected in multiple environments;the TIL14 introgressed population was located 29 QTL loci,of which 5 loci can be detected in multiple environments.3.WGCNA analysis of of two introgressed populations showed that 4 modules were significantly associated with plant height,leaf length and spike branch number in TIL11population,and 5 modules were significantly associated with phenotype in TIL14population.The genes in the modules were enriched by GO,and it was found that each module was mainly related to biological processes and functions such as biological stimulus response,peroxidase activity,chlorophyll formation,and cellulose synthesis.4.The eQTL analysis results of the 2 introgressed populations showed that the expression of a total of 3,901 genes in the TIL11 population was regulated by at least one eQTL site,of which 1,441 genes were regulated by cis-eQTL;a total of 15,923 genes in the TIL14 population were regulated by at least one eQTL locus,of which 2,786 genes were regulated by cis-eQTL.5.Integration of important agronomic traits QTL mapping results,WGCNA phenotype significantly related module information,as well as eQTL control of network information,comparative analysis,found that there are seven genes in three kinds of analysis results are all associated with traits,1 associated with plant height,1 associated with long leaf traits,1 related to leaf width character,4 associated with tassel branch number.2 candidate genes were identified:Zm00001eb001980 was associated with plant height trait and Zm00001eb362160 was significantly associated with leaf width trait,providing target genes for subsequent functional verification.In this study,2 introgressed populations were constructed,and 9 important agronomic traits were investigated at 3 environments.3’RNA-seq was performed to obtain their genotype and gene expression data,then genetics and bioinformatics techniques are combined,74 QTLs that significantly affect the variation of important agronomic traits were located,and the genetic basis of the variation of the introgressed population was preliminarily analyzed.By further using WGCNA analysis and eQTL mapping analysis,7candidate genes that highly correlated with height,leaf length,leaf width,and tassel branch number were excavated.The introgressed populations constructed in this study and the results of genetic analysis provide excellent genes and germplasm resources for further genetic improvement of maize,and have important theoretical and practical value.