Genetic Mapping Of LFI1,a Key Gene Mediating Stem Apical Meristem Differentiation And Its Candidate Expression Analysis In Maize

Maize is an important economical crop.Dissection of the mechanism of shoot apical meristem（SAM）and inflorescence formation in maize is associated with productivity improvement in maize.In this study,a SAM deferentiation-related mutant,called lfi1（leafy Inflorescence 1）,and the genetic mapping and relevant gene expression were performed.This study provided the valuable information for the final cloning and function analysis of lfi1 gene,which was thought to be helpful to understand the molecular mechanism of SAM differentiation in maizeThe segregation of mutation phenotypes in F2 and BC1 populations derived from B73x lfi1 mutant showed inheritance segregation ratio of 3:1 and 1:1,which indicated that lfi1was a recessive mutation for inflorescence development.With BSR-Seq expreriment we mapped the lfi1 gene into a region of 22.3 Mb With F₂ population of B73 x lfi1,we screened 82 single-crossover plants using In Del markers and the lfi1 was found to locate in a 2.59-Mb region of chromosome 7,which contained 54 annotated genes.RNA-seq of leaves showed there are 2352 differentially expressed genes（DEGs）between wild type and mutant.Nine DEGs were located in the 2.59 Mb-region.These nine DEGs were considered as candidate genes of lfi1,and four of them were up-regulated and five of them were down-regulated in the mutant as compared to WT.q RT-PCR was used to analyze the nine selected candidate genes in mutant vs.wild-type in leaves（V3）,root tips（D3）,SAM（V6-V9）and ear primordium（4-5mm,6-10mm,10-15mm）.The gene expression analysis revealed that Zm00001d020937（Zm937）and Zm00001d020938（Zm938）have significantly lower levels in SAM and ear primordium in the mutant as comparied to WT.Zm00001d020867（Zm867）and Zm00001d020909（Zm909）showed higher levels in the mutant comparied to WT.Other five genes have significant difference between mutant and WT.Therefore,we selected Zm937 and Zm938 as final candidate genes of lfi1.We expected lfi1 gene could be either Zm937 or Zm938,which involving in the process of SAM floral deferentiation in maize.