Fine Mapping Of Maize Kernel Mutant 15m1 Gene

Corn is an important food,feed and energy crop,and the grain is the storage organ that determines its yield and quality.Cloning and functional research on the key genes controlling the grain size of corn can not only enrich the genetic mechanism of corn grain development and formation,but also provide a theoretical basis for the breeding of new high-yield corn varieties.Mutants are good materials for gene cloning.According to the variation of grain phenotype,maize grain mutants can be divided into defective type(dek),empty pericarp mutants(emp),opaque mutants(opaque),translucent mutants(floury),and small grain mutants(smk).The mutant used in this experiment was the grain mutant 15m1 found in the process of breeding and selection.The grain length,grain width,grain thickness and 100-grain weight of the mutant were significantly lower than those of the wild type.At 10 days after pollination,the development of mutant grains on the ear of a single plant with heterozygous genotype began to lag behind that of normal grains.Compared with wild-type seeds,mutant seeds had only 30% bud rate and grew slowly after seedling.Cytological analysis showed that the embryo and endosperm of the mutant were smaller than those of the wild type,and the endosperm starch was less filled,and the endosperm basal metastatic layer lacked cell wall proliferation.Control for cloning the gene mutation,we use of mutant and zheng 58 equipping the F2 segregation population,genetic analysis showed that the normal grain produce 1:2 not separate clusters: separation of grain,grain on grain with normal mutation and all separation grain separation ratio is in line with the ratio of 3:1,indicated that the mutant is controlled by a single recessive nuclear gene.The dominant and recessive pools were constructed from the normal and mutant seeds of F2 isolated populations,respectively.Polymorphic markers were screened by BSA method.Six linked polymorphism markers on chromosome 2 were screened from 200 pairs of In Del markers covering the whole genome.Further validation by developing markers and large groups,eventually using 466 homozygous recessive grain and 17 chain polymorphism marker position candidate genes to physical range of 737 kb,due to the area between the near telomeres,cannot continue to narrow range,we to the wild type and mutant RNA-seq analysis of seed,although found some insert/delete and SNP,but uses the In Del and validation d CAPs markers as invalid markup.There were a total of 15 protein-coding genes in the B73 reference genome,among which 4 genes were not expressed in the grain.Sequencing analysis of 11 genes expressed in seeds showed no difference in c DNA between wild-type and mutant.The expression of gene 71 was significantly different between wild-type and mutant,but no variation of its regulatory sequence was found in the upstream 3 kb of ATG.With the release of more reference genomes of maize inbred lines,we found that other inbred lines were significantly different from B73 in this region,and there were still other genes.We speculated that the background of 15m1 mutant was different from that of B73,so that the markers designed according to the sequence of B73 were invalid in the mutant background.Therefore,we need to verify these extra genes in the future to determine the candidate genes.