Genetic Analysis And Fine Mapping Of A Recessive Dwarf Mutant Gene Dm1 In Maize

Dwarf mutants are crucial for elucidating regulating mechanisms of plant growth and development.these are also favored in plant breeding.With the continuous of new dwarf materials,the identification of new dwarf genes and the study on the relationship between different dwarf genes and the values of use of different genes are becoming more and more urgent.In this study,a new maize dwarf mutant was found and the gene was fine mapped by map-based cloning and Genetic analysis of the gene,the results were as follows:1. Discovery of a new recessive dwarf mutant in maize and its preliminary analysis:The dwarf mutant was a material of Variation,which was found in field.The plant height was about 40-50 centimeters tall,it was very low,and it could get homozygote line by selfing.2. Genetic analysis of plant height:Based on the analysis of the population variations of plant height in hybrids including F1 、 F2 and BC1(backcrossed to dwarf parent)derived from five cross combinations between a dwarf mutant and tall inbreed lines B73 、 87-1 and chang7-2:the F1 individuals were as tall as the inbreed parents;and the segregation of the F2 generation appeared to be 3 tall:1 short,the dwarf F1 hybrids with the new dwarf gene were backcrossed with the dwarf mutant parent,the proximately segregation ratio of BC1 populations was 1 tall:1 short.So the dwarfing effect of the new gene was confirmed,and indicated that the dwarf trait was controlled by one recessive gene.3. Dwarfing mechanism of maize dwarf mutant:In the segregation of the BC1 population,The dwarf plant than dwarf mutants were higher 10-20 centimeters average.Compared with high plants, they are characterized by internode shortening, and in three BC1 segregation groups, their corresponding internode ratio change is consistent, is fall after rise first, and then increased. Through to the dwarf mutant gibberellin treatment found that processed plant has the corresponding degree rise, show that dwarf mechanism may be related to gibberellin.Cytological study found internode shortened due to cell elongation.4. Fine mapping of dm1 gene:Dwarf mutant and B73, 87-1 and chang 7-2 hybrid backcross population produced by the plant height is divided into two kinds, tall plants and dwarf plants. 2000 strains with B73 segregation population to preliminary positioning of the gene, the results indicated molecular markers on chromosome 3,phi053 、umc2265、 umc2166 and umc1399 linked with dm1 genes, data analysis showed that the gene between mark umc2265 and umc2166, genetic distance is 2.5 c M and 5.4 c M respectively. In previous positioning on the basis of the development, in 240 SSR molecular markers,three segregation groups respectively have polymorphism primers screened out 14 for B73, 8 for chang 7-2,10 for 87-1. Building B73 segregation group fine mapping, 5000 strains of the gene will eventually dm1 gene mapping between marking the 4-3-3 d and 4-3-3 f, physical distance between two markers about 240 kb.5.The choice of candidate genes:On the basis of fine mapping of gene,we forecast the located interval sequence,only to find a gene,the gene sequence number is GRMZM2G085113.This made a solid foundation for gene cloning and functional studies.