Using Tropical Maize R146 To Mine QTLs For Flowering Time

Maize（Zea may L.）is the largest food crop in the world.The flowering time traits of maize are regulated by multiple factors.The mining of candidate genes related to maize flowering time has guiding significance for the study of molecular mechanism of maize flowering time and the improvement of maize germplasm.In this study,two tropical inbred lines,R146 and its early flowering time natural mutant ER146 were crossed to produce F₁generation and then self-cross to produce F₂ population of 901 individual plants.Days to silking（DTS）is an important trait of maize flowering time.In F₂ population,30 plants were selected from the extremely early and extremely late days to silking（DTS）of maize,and two extreme DNA mixing pools were constructed for bulked segregant analysis（BSA）.The molecular markers used in the analysis were single nucleotide sequence（SNP）and insertion and deletion（In Del）markers.Quantitative trait loci（QTL）and minor effect loci were obtained by combining the Euclidanian distance（ED）algorithm withΔSNP-index/ΔIn Del-index algorithm in BSA.Functional annotation of candidate genes was also made.The main results are as follows:（1）Localization of QTL and minor effect loci related to DTS of BSA.5 ED-QTLs were obtained from the whole genome by ED value method,which were located on chromosomes1,2,3,8,and 9,respectively.The ED-QTL with the largest range and highest peak value was found on chromosome 3,which contained 402 genes with the region size of 22.2 Mb.1main effect ΔSNP-QTL with region range of 0.268Mb（ΔSNP-q DTS3-2）and 19 minor effect loci were detected in the ED-QTL byΔSNP-index/ΔIn Del-index method.（2）Functional annotation of candidate genes.4 genes in the main effectΔSNP-QTL and 13 genes in the minor effect loci were functional annotated,and it was found that 1 gene in the main effectΔSNP-QTL and 5 genes in the 9 minor effect loci were related to the flowering time of maize.Including MYB transcription factor,SEUSS transcription factor,GRAS transcription factor and JINGUBANG like proteins.In addition,2 potential new maize flowering time genes were found inΔSNP-QTL,which had no functional annotation and related homologous gene information,and only existed in a few maize genomes.The QTLs and related genes detected in this study provide a theoretical basis for the study of QTL hot spots,gene expression analysis and functional verification in maize flowering time,and provide a practical basis for mapping such complex quantitative traits in maize by BSA method.It also provides an effective way to improve temperate germplasm of tropical maize.