GWAS Analysis For Genetic Basis Of Brace Root Diameter And Angle In Maize

Maize is the largest economic crops in China,with the adjustment of planting structure in our country,agricultural mechanization harvest has become an important part of agricultural development.Lodging is affect maize yield and plant can be one of the important factors for mechanical harvesting,studies have shown that affect multiple related traits of lodging resistance,corn root traits were the main influencing factors,especially for the root or reverse type lodging decisive,lodging resistance of maize and the brace root number,brace root diameter,brace root layer was significantly positively related.But most study only stay on the phenotypic traits and the research of the relationship between lodging.However,previous studies mostly stayed in the correlation study between phenotypic traits and lodging,and did not deeply understand the molecular mechanisms that control the domestication of maize roots and analyzed the molecular regulation of brace root formation.Therefore,it is very important to use GWAS technology to mine the key genes that affect the growth and development of maize brace roots.This study used 508 inbred lines from all over the world as materials to build large-scale shape identification of associated group,adopt to analyze these important brace root traits data by GWAS analysis,excavate impact angle and the diameter of brace root loci of maize in order to get the candidate gene function,the result for cultivating the capability of resistance to lodging of maize varieties to provide molecular theory basis.The main results are as follows:1.Genetic basis of brace root diameter traits in related populationsThe diameter of the brace root passes through liaoning and jilin two environments(of which liaoning carries on the experiment of 2016 and 2017,twice repeated,jilin 2016 experiment once repeated).According to the survey data obtained satisfy normal distribution,the generalized heritability of 0.89 present a higher level.As for GWAS analysis,we use the MLM model,when the threshold selection for more than 5,there are 4 significant independent SNPS loci were detected,respectively located on chromosome 1,9,10 and choosing threshold between 4 and 5,we detected 20 associated SNPS loci all chromosomes are distributed except for chromosome 9 and 10 and phenotype contribution rate was 21.85%.We found 24 candidate genes by positioning the SNP loci analysis,and homologous gene in arabidopsis thaliana as a candidate gene functional annotation.Known function of the candidate genes were divided into several functional types,including the synthesis and metabolic pathways,signal transduction pathways,transcription regulation pathway,and DNA/RNA editing.2.Genetic basis of brace root angle traits in related populationsThe angle of the brace root passes through liaoning and jilin two environments(of which liaoning carries on the experiment of 2016 and 2017,twice repeated,jilin 2016 experiment once repeated).According to the survey data obtained satisfy normal distribution,the generalized heritability of 0.80 present a higher level.As for GWAS analysis,we use the MLM model,when the threshold selection for more than 5,there are 4 significant independent SNPS loci were detected,respectively located on chromosome 1,3,6,8,10 and choosing threshold between 4 and 5,we detected 18 associated SNPS loci on chromosome 3,4,5,7,8,and 10 and phenotype contribution rate was 22.35%.We found 24 candidate genes by positioning the SNP loci analysis,and homologous gene in arabidopsis thaliana as a candidate gene functional annotation.Known function of the candidate genes were divided into several functional types,including the synthesis and metabolic pathways,signal transduction pathways,transcription regulation pathway,protein processing,and DNA/RNA editing.