Genome-Wide Association Study And Genomic Selection Of The Main Agronomic Traits In Maize F1 Population

Maize(Zea mays L.)is one of the most important grain crops in China,and increasing its yield is of great significance to ensure national grain security.Maize is a cross-pollinated crop that utilizes heterosis,and the F1 population is a widely used population in actual agricultural production.Although the genetic basis of its main agronomic traits has been extensively studied using different populations during the past decades,the genetic mechanism in the F1 population needs to be further studied.The research results based on the maize inbred lines population can not be directly used to reveal the genetic mechanism of the maize F1 population,and the traits with obvious heterosis can only be studied by hybrids.Therefore,compared to the crop with strong heterosis,such as maize,it is necessary to use the maize F1 population for studying.In this study,a total of 300 hybrids which were constructed through incomplete diallel crosses using 99 maize inbred lines were used as research material.Based on 17,652high-quality SNP markers,a genome-wide association study(GWAS)and genome selection(GS)was conducted about eleven major agronomic traits,i.e.,PH,EH,DTS,DTA,EL,ED,ETB,KRN,KNPR,HKW,and GWPP,in order to identify candidate genes,predict excellent hybrids,enrich the understanding of the genetic basis of these traits and provide guidance for maize breeding.The main research results were as follows:1、The analysis of population structure shows that 99 parental inbred lines can be divided into two subgroups: tropical group and temperate group.The tropical group includes 40 inbred lines,and the representative inbred line is ZNC442;the temperate group includes 59 inbred lines,and the representative inbred line is Jing 724.300 hybrids can be divided into four subgroups,namely hot-hot hybrid group,warm-temperature hybrid group,warm-hybrid group,and mixed group,including 75 hybrids,64 hybrids,116 hybrids,and45 hybrids,respectively.2、A genome-wide association study(GWAS)was conducted about PH and EH of the F1 population,as a result,two possible candidate genes of PH which were Zm00001d018617 and Zm00001d023659,and four possible candidate genes of EH which were Zm00001d032664,Zm00001d032613,Zm00001d006348 and Zm00001d048894 were identified.3、A genome-wide association study(GWAS)was conducted about DTS and DTA of the F1 population,as a result,one possible candidate gene of DTS which was Zm00001d047501,and two possible candidate genes of DTA which were Zm00001d020177 and Zm00001d047501 were identified.Moreover,the candidate gene Zm00001d047501 was a candidate gene that was identified together.4、A genome-wide association study(GWAS)was conducted about seven yield-related traits of the F1 population,i.e.,EL,ED,ETB,KRN,KNPR,HKW,and GWPP,as a result,no candidate gene of GWPP was identified,and two possible candidate genes of EL which were Zm00001d029571 and Zm00001d004125,two possible candidate genes of ED which were Zm00001d028005 and Zm00001d052314,one possible candidate gene of ETB which was Zm00001d005978,three possible candidate genes of KRN which were Zm00001d028317,Zm00001d002468 and Zm00001d017649,one possible candidate gene of KNPR which was Zm00001d013919,and two possible candidate genes of HKW which were Zm00001d051186 and Zm00001d039188 were identified.5、According to genomic selection(GS),it was found that the size of the training population and the heritability of the traits would affect the prediction accuracy.Based on the estimated breeding value of the genome,a total of 100 potential excellent hybrids were selected,and the average yield of the 100 hybrids was increased by 18.47% compared with the population average.