Screening And Identification Of Dwarf Stem Mutants In Maize

Plant height is one of the important agronomic traits of maize,which has important effects on planting density,lodging resistance,population permeability and photosynthetic efficiency of maize in the field.Reasonable plant height plays an important role in improving yield and quality of maize germplasm.Maize plant height has a complex regulatory mechanism,and several genes regulating maize plant height have been identified.Further exploration of dwarf stem genes is conducive to the further analysis of its mechanism and the further cultivation of new maize varieties through molecular markers and other auxiliary technologies,so as to increase the planting density and increase the yield of maize.In this study,Ethyl methane sulfonate（EMS）was used to mutate Zheng 58 inbred lines to obtain a series of different dwarf mutants.Field character investigation was conducted on the mutants,morphological observation was conducted on stem cells of dwarf bar mutants,and cell size and number were counted.Dwarf mutants and 4 inbred parents with different plant heights were used for hybridization experiment,and yield investigation was conducted on hybrid offspring to analyze the potential ability of dwarf mutant to improve corn yield.The main research results are as follows:1.According to the field character investigation of the mutant,compared with the control plant,the plant height and ear height of the dwarf stem mutant of corn were reduced to different degrees,the mutant’s plant height was reduced to 10%⁴5%,and the spike height was reduced to 10%⁶5%,indicating that the plant height had a strong influence on the spike height.Compared with the control group,the length of spike of mutant fruit was shortened by 4.1%³5.5%,the row number of spike decreased by 2 rows on average,the row number of grain decreased by 12.0%⁴5.2%,the average yield of single ear decreased by 20.2%⁶1.3%,and the diameter of ear decreased by 1.5%⁶.9%.Nine dwarf mutants with better plant type and suitable for dense planting were screened out.In addition,five mutants with no significant yield change compared with the control were screened out.2.According to the observation of stem cells,stem cells of all the mutant materials were shorter than those of the control materials,and the shortened range was 25%⁷5%.The height of the mutant 5851and 5858 was mainly caused by the decrease of cell length,and had nothing to do with the number of cells.3.The dwarfing mutant with four inbred lines of hybrid F₁ plant height and grain yield analysis found that dwarfing mutant production of 5862,5863,5873,5874,5879 compared with Zhengdan 958 very close,therefore,dwarfing mutant 5862,5863,5873,5874,5879 can be used as a short stalk resource materials,by increasing the planting density to increase maize yield,thus the best synthetical properties for breeding new maize varieties to provide new ideas and materials.4.BSR high-throughput sequencing was performed on the mutant with recessive gene controlling plant height,and combined with bioinformatics analysis,the mutation of Zm00001d039453 base in 5858caused the termination mutation of amino acid.Zm00001d039453 belongs to the cytochrome P450family,which is a terminal oxygenase.The function of Zm00001d039453 gene is related to the synthesis of brassica napus lipid,the steady state of brassica napus steroid and the development of cell tissue,and is involved in the synthesis of sterol hormones in organisms.The homologous protein Os01g0197100 of Zm00001d039453 can cause the dwarfing of rice,resulting in the reduction of rice node spacing,especially the severe shortening of the top second node,and the decrease of leaf Angle.The phenotype of 5858 dwarf mutant was that the plant height decreased,the stem became thicker,the leaf Angle decreased,and the pitch decreased.Therefore,it was speculated that the function of Zm00001d039453 gene changed,thus causing the mutant 5858 to dwarf.