Fined Mapping And Candidate Gene Analysis Of Maize Small Kernel Mutant

Maize is not only an important food crop that can provide food for human beings,but also a source of feed,industrial and energy raw materials.It is also a model crop for basic biological research.In the past 100 years,maize mutants have played important roles in studies about plant cytogenetics,quantitative genetics,epigenetics,biochemical metabolism,transcription factors and mutations,as well as biological evolution and domestication.With the completion of maize genome sequencing,further researches on function of genes about maize yield and quality were comprehensive in-depth.The relevant studies not only can be favorable to provide a theoretical basis for the genetic improvement of maize yield and quality,but also may provide a reference for the relevant researches of other crops,such as wheat,barley,and sorghum.In this study,phenotypic identification and gene cloning were carried out employing the recently identified maize mutant with small kernel,which is expected to provide excellent candidate genes for breeding of maize grain yield traits.The main results are as follows:1.The maize mutant exhibited small kernel,thus it was named small kernel mutant?skm?.The character of small kernel can be inherited stably,after multiple generations of self-cross.F₁ population was in constructed from the hybridization between skm and inbred lines B73and Mo17,respectively.All are normal grain in F₁ population,and a separation ratio of 3:1between normal grain and mutant grain of F₂ panicle was accordance with Mendelian genetic law,indicating that its mutant character was controlled by recessive single gene.2.Compared with B73,grain traits of skm showed smaller grain size,wrinkled seed coat at the top,seriously absent keratin,decreased content of mature endosperm protein and starch content,changed starch granules size,shape and arrangement space.3.The preliminary gene location of skm was conducted with the F₂?B73×skm?population using the Bulked Segregation Analysis?BSA?.The skm was located in the genetic region?134.8-152.7 Mb?between IDP7741 and IDP7532 marked by InDel on maize chromosome 7.4.Construction of F₃?B73×skm?population,the mutant gene was further narrowed down to the 70 kb interval between ZM227 and ZM234 of SNP on chromosome 7 of maize using Mapping-by-sequencing?MBS?and Penta-primer amplification refractory mutation system?PARMS?sequencing.Finally there were 5 genes in the candidate region.Combining the sequence comparison results,expression conalysis and gene function annotation of the 5candidate genes,the target genes were further screened.