| Maize is the world's most important food crops,has thousands of years of planting history,as food crops in the High-yield crops and multiple cash crops,maize in agricultural production has a vital position.Maize is not only important food crops,to meet people's needs for food and clothing,but also feed,industrial production,bio-energy and other major sources of supply,with the changing and development of the Times,the global demand for maize more and more high.In terms of drought resistance,seedling is the first stage of the whole growth period of maize,and the survival rate of maize seedling determines its future growth,quality and yield.The growth of maize seedling will be affected by the drought area in north China.Better drought resistance is the basic requirement to ensure the seedling survival and final yield.Therefore,we should increase the interest in maize knowledge,strengthen the knowledge of maize,scientifically cultivate high yield,drought-resistant maize,change the traditional planting mode,choose the correct and beneficial planting way,improve the harvesting efficiency,increase the production greatly,meet the people's increasing material demand.In this experiment,a total of 191 inbred lines were used as materials by the mo17x(mo17/x26)chain group,and the Mo17 belonged to Lancaster Group,which had the advantages of wide adaptability and lodging resistance.X26 is the great humble grass(teosinte),It is a general term originating from the annual and perennial maize plants in Mexico and Central America.The 20%PEG6000 solution was used to irrigate and simulate the drought stress in three leaves,and then the morphological characters of 7 maize were tested,including plant height,root length,fresh weight,root fresh weight,plant dry weight,root dry weight and root-crown ratio.The QTL of 7 morphological characters in maize seedling was found and identified by means of linkage analysis.In this paper,the SNP labeling method was used to locate the QTLS preliminarily and to obtain the candidate genes of drought-resistance related traits in maize seedling stage.The main findings are as follows:(1)in the normal control group of the MX RIL Group,7 characters all showed normal distribution,the best linear unbiased prediction(BLUP)showed close to the median,and did not appear the hyper-pro genetic phenomenon,indicating that the alleles controlling these 7traits existed in the parents.The correlation coefficient is from 0.02 to 0.88.The results of variance analysis showed that genotype had significant effect on plant height and fresh weight,and had a significant effect on root fresh weight and root dry weight trait.The generalized heritability(H~2)of plant height,root length and fresh weight were moderate,50.69%,43.41%and 46.71%respectively,and the generalized heritability of root fresh weight,plant dry weight and root dry weight were 20.75%,30.35%and 22.22%respectively.The generalized heritability estimates for 5.88%(2)in the MX RIL group were lower than that of the root-shoot-ratio traits,plant height,root length,fresh weight,root fresh weight and root dry weight characters all showed normal distribution,indicating that the alleles controlling these 5 characters existed in the parents,and only the dry weight and root-crown ratio were left.The best linear unbiased prediction(BLUP)showed that 7 characters of the MX group were close to the median.The correlation coefficient is from 0.0019 to 0.78.The results of variance analysis showed that the genotype had a significant effect on the remaining 6 characters except the dry weight of the plant.The generalized heritability(H~2)of the plant height,root length and fresh heavy-form data was moderate,64.46%,63.1%and 53.9%,respectively,indicate that the phenotypic variation of these three traits is determined by the genes of the MX RIL group;generalized heritability of(3)Stem weight and root-crown ratio of phenotypic data(H~2)The lower estimates were2.34%and 7.4%,indicating that phenotypic variation of the two traits was less affected by genotype.(4)The WinCart2.5 software was used to analyze two repetitive and optimal linear unbiased predictive values of 7 maize drought-resistance related traits,a total of 9 main qtl were obtained,among which plant height(PH)1,root length(RL)2,Root fresh weight(WRW)2,Plant dry Weight(DPW)1,Root dry weight(DRW)2,root-crown ratio(RSR)1.The 9 main qtl were on 2,3,4,5 and chromosome 8th,respectively.The explanatory phenotypic contribution rate is from 6%to 10.25%.(5)we counted the recombinant breakpoints of the main QTL interval of 9 maize drought resistance traits.The bin map was redivided according to the reorganized breakpoint,and the QTL interval was shortened to the two interbreak points with the highest LOD value.The physical distance of vertex bin from 0.12 Mb(qMXRL2-2)to 8.86Mb(qMXDRW3-2)contains 12 to 413 genes.A total of 1166 genes were found and 14 candidate genes were found.Theyare:GRMZM2G129034,GRMZM5G848945,GRMZM2G024933,GRMZM2G400559,GRMZM2G099593,GRMZM2G304745,GRMZM2G424682,GRMZM2G081892,GRMZM5G800586,GRMZM2G158013,GRMZM2G055240,GRMZM5G863385,etc.Among them,7 belong to signal transduction pathway,5 belong to transcriptional regulation pathway and 2 belong to metabolic pathway. |
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