| Maize(Zea mays L.)is one of the world's important food,economic and forage crops,which plays an irreplaceable role in maintaining world food security.The directional selection of human beings in the production process has led to the increasing shortage of maize germplasm resources,making the selection of excellent maize varieties more and more difficult.Teosinte(Zea mays SSP.Parviglumis),as a wild related material with the closest genetic relationship to maize,is not only significantly different from maize in phenotype,but also superior to maize in plant diseases and insect pests resistance and stress tolerance.it has many excellent allelic resources that can be applied to maize trait improvement.Therefore,it is of great significance and application value to construct backcross recombinant inbred lines of maize and teosinte and analyze the genetic basis of phenotypic differences between maize and teosinte.Three maize-teosinte BC2-RIL populations,Zheng 58×Parviglumis(ZP),B73×Parviglumis(BP)and B73×Diploperennis(BD)were constructed in this study.Phenotypic identification and genetic evaluation were carried out on day to tassel,day to anthesis,day to silking 3 flowering traits and plant height,ear height,number of tassel branches,length of tassel 4 plant architecture traits respectively in 4 environments of 2 years.88 families and their parents B73 were randomly selected from BD population for resequencing.Genome variation information of different families in the population was detected,and teosinte introgression fragments were identified.Linkage analysis of target traits was carried out in combination with phenotypic data.The main results are as follows:(1)In maize-teosinte BC2-RIL population,the ear height and the number of tassel branches have great variation in the three populations.The target traits have high broad heritability in all populations,ranging from 0.69 to 0.90,indicating that the variation of the tested traits is greatly influenced by heredity.Correlation analysis showed that there was a significant positive correlation between flowering traits such as day to tassel,day to anthesis and day to silking.Meanwhile,there was a significant positive correlation between the three flowering traits and ear height.Plant height was significantly positively correlated with ear height and length of tassel,ear height and number of tassel branches also showed significant positive correlation,but there was no significant correlation between number of tassel branches and length of tassel.In addition,length of tassel was significantly negatively correlated with day to tassel and day to anthesis in the three populations.There were significant differences between recombinant inbred lines and maize parents in ear height,number of tassel branches and length of tassel.(2)Based on the resequencing data of 83 families in BD population,653 869 high quality SNPs and 564 752 InDels were screened.SNP mutation types are mainly transformation,accounting for 64.2% of the total number,the length of InDels is between 1-200 bp,and there are 447784 indels of 1-4 bp.Adjacent or linked consecutive SNPs are combined into one block,and 3214 blocks are integrated by using the detected high-quality SNPs.Statistical analysis of teosinte fragments in backcross recombinant inbred lines showed that the average number of teosinte chromosome fragments contained in each family was 162,and the average length of these exogenous fragments was 60640 bp.The family background recovery rate is 98.33%-99.77%,and the average recombination exchange event frequency per family is 79-282.The overall recombination event frequency distribution is highly consistent with the distribution of teosinte exogenous fragments.(3)Based on Blocks and the phenotypic data of 83 families,19 Blocks significantly correlated with traits were identified,of which one block correlated with ear height was identified in two environments.Taking 83 BD population families as mapping population,a genetic linkage map with a total length of 13638.1cM was constructed by using R/qtl.QTL mapping for target traits was carried out,and a total of 70 QTLs were detected.The number of QTL detected for different traits varied,with 24 QTLs at ear height.The number of QTL related to the number of tassel branches and length of tassel is the least,only 2.There are 18 QTLs co-located in multiple environments,which indicates that these QTLs are stably expressed in different environments.The phenotypic variation explained by a single QTL was 19.76%-31.97%.There are 3 Blocks on chromosome 9 that are included in QTL mapping interval and are significantly associated with traits,of which 2 are associated with day to tassel and day to silking,and the other is associated with day to silking. |
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