Preliminary Location Analysis Of Maize Dwarf Mutant Gene

Maize is the main food and feed crop,which plays an important role in national economy and agricultural production.With the continuous reduction of cultivated land area and the increasing demand for corn,cultivating high-yield new corn varieties is a relentless goal of breeders.The increase in corn yield is inseparable from the identification and utilization of excellent maize germplasm resources.Plant height is one of the most important plant type traits that determine corn yield.By reducing plant height,increasing planting density,and improving lodging resistance,the yield per unit area can be continuously increased.At present,most of the identified dwarf germplasm are linked to various undesirable traits,which restricts the application of dwarf germplasm in the improvement of maize varieties.Therefore,it is necessary to discover and identify new dwarf germplasm and accelerate the cultivation of corn dwarf varieties.In this study,the mutants produced in the HII tissue culture process were used as the father and hybrid with the maize inbred line B73,and the dwarf mutants D72,D72 and B73 were obtained from multiple generations,and the D72 and B73 hybrids and selfed.The F₂ population and the BC₁F₂ population with B73 as the recurrent parental backcross and self-intersection were used as experimental materials to study the inheritance of the dwarf mutant,and the BSA-SSR method was used to backcross and self-crossing D72 and B73.The BC₁F₂ segregating population performs initial gene mapping.The research results are as follows:1.Genetic analysis: Genetic analysis of the F₂ population of D72,B73,D72 and B73 positive and negative crossover populations,D72 and maize inbred line B73 hybridized and selfed,and the BC₁F₂ isolates backcrossed and selfed by B73 showed that:D72 and B73 the positive and negative crosses showed high stalks,and there was no significant difference in plant height,indicating that the dwarf gene had no cytoplasmic effect and was nuclear inheritance.Statistical analysis of the separation ratio of tall and dwarf plants in F₂ population,in line with the expected value of 3:1.The separation ratio of high and dwarf plants also met the expected value of 3:1 in the BC₁F₂ isolated population.It is shown that the dwarf gene is a single recessive gene of nuclear inheritance.2.Phenotypic analysis: Field traits of tall and dwarf plants in the BC₁F₂ population produced by cross-breeding and self-crossing of F₁ and F₂ populations produced by D72,B73,D72 and B73 showed that tall stalks were higher than dwarf mutants.The normal elongation of the internodes above the ear position of the plant did not change significantly,but the internode length was significantly shortened in the ear and below,indicating that the plant height reduction was caused by a significant shortening between the internodes in the ear and below.In addition,the dwarf mutant tassel developed well and normal powder was loosened,and the shape,length and width of the leaf did not change significantly.These results indicate that the mutant we created is different from the characteristics of the dwarf mutant found in the previous generation,and it is speculated that the dwarf mutant may be regulated by a new dwarf gene.3.Cytological observation: The results of cross-cutting of the stems,spikes and internodes of the tall and dwarf plants in the BC₁F₂ population with B73 as the recurrent parental backcross and self-crossing showed that the dwarf plants were the cell length between the internodes and the ear position was shortened,and the cell size at the internodes of the panicles did not change significantly,indicating that the dwarfing of dwarf plants was caused by shortening the length of stem cells in the ear and below.4.Mapping of dwarf genes: The BSA-SSR method was used to locate the BC₁F₂ isolated population of D72 and B73 backcrossed and selfed,and the dwarf gene was initially located at 6.03 of the whole genome of maize.The position of the bin is located between the molecular markers s11050 and s11337,the genetic distance is 17 c M,the physical distance is 30 Mb,and the positions of py1（tan1）（6.05 bin）,rd2（6.00 bin）,and xlg3（6.01 bin）are different,and There is a big difference in phenotypic traits,which is probably a new dwarf gene.