Initial Mapping And Analysis For Leaf Width QTL By Whole Genome Resequencing Of DNA From Two Bulked Populations Of Maize

Maize(Zea mays L.)is an important grain crop,feed and industrial raw in our country,with the reduction of arable land,the population continues to increase,corn demand is also increasing.Therefore,improve yields,increase the total production of maize breeding is an important goal long sought.Leaves are the main site of maize for photosynthesis,and the size and shape of leaves are important factors in determining plant type.Leaf width is one of the main agronomic traits of leaf type,the genetic regularity and molecular basis of maize leaf width were analyzed,which plays an important role in mitigating the shade effect between individuals by increasing the density of maize.In this experiment,a pair of maize inbred lines with significant differences in leaf width traits,the extreme individuals in the F2 population were selected for resequencing and got the difference SNPs site between the two pools as a candidate region for regulating leaf width.Through the bioinformatics analysis,the SNPs in the candidate region are annotated and obtain genes related to leaf width.These results provide theoretical and technical support for cloning and molecular mechanism of leaf width-related genes,and selection of excellent maize varieties with strong tolerance.The main results are as follows:A F2 population of 269 plants was constructed from maize width-leaf inbred lines Yu 816 and narrow-leaf inbred lines Yu 667.Phenotypic identification of maize leaf width in 2016,15 plants of extreme width-leaf and narrow-leaf plants were selected from the group,composition of wide and narrow two mixing and parents pool.Mixed pool resequencing results showed that: there were 1.76 million mutation sites(SNPs and INDELs)in four sequencing pools.A total of 177,322 mutation sites occurs in exon were obtained by F2 population comparison with parental sequencing,using the confidence interval of ?SNP-index at 0.01 confidence level and combined with bioinformatics analysis,which mutations were mainly distributed in 10 candidate regions of the second chromosome and corresponding to 10 QTLs.A total of 782 genes were identified in these mutations,by GO analysis,these genes are mainly concentrated cellular process,metabolic process,single-organism process,biological regulation,response to stimulus,cell part,organelle,membrane part,membrane,organelle part,binding and catalytic.Through the study of these genes in other crops found that 13 genes in other plants involved in growth and development,which GRMZM2G052078,GRMZM2G175504,GRMZM2G083972,which are involved in the regulation of cell division and differentiation GRMZM2G444808,GRMZM2G055883-TO1/T02,GRMZM2G083972 regulate the polarity of cells,GRMZM2G054795,GRMZM2G099862 silencing or deletion causes leaf narrowing,GRMZM2G122614,GRMZM2G041127,GRMZM2G009478,GRMZM2G009188,GRMZM2G425366 have the function of regulating plant hormone,these genes are located in 6 QTLs.Especially the gene GRMZM2G122614 of the auxin response factor in q16LW2-3,the gene GRMZM2G444808 plays an important role in cell growth and proliferation in q16LW2-6,the gene GRMZM2G009188 involved in the signal transduction of BR in q16LW2-8,this three candidate genes occur early termination or frameshift mutations,which indicating that these three sites may be a key area for regulating leaf width.Compared with the QTLs of maize leaf width with predecessors,six QTLs(q16LW2-1,q16LW2-2,q16LW2-3,q16LW2-4,q16LW2-8,q16LW2-9)mapped in the experiment overlapped the previous loci.There are four overlapping QTLs in which there are candidate genes related to growth and development,which results indicate that these QTLs belong to the hotspot region that regulates leaf width.