Construction Of Chromosome Segment Substitution Line And QTL Mapping Of Plant Height In Maize

Many important agricultural traits of maize are quantitative traits. The hereditary basis of these traits are significant for breeding improvement. Construction of an effect mapping population is the base of gene mapping and identification of quantitative traits. Chromosome Segment Substitution Lines(CSSLs) is a secondary mapping population produced by backcrossi ng and marker-assisted selection. The characteristic of CSSLs are simple to genetic background and accurate to phenotype identification. Furthermore, CSSLs could be directly used for QTL fine mapping and QTL identification with a high-density genetic map on recombinant inbred lines. Plant height is an important agronomic trait to yield and lodging resistance of maize, which is an significnat indexes to measure the excellent variety of maize. Gene mapping, cloning and functional research of plant height, are important for breeding and germplasm improvement of maize. The main results are as follows:(1)In this research, elite inbred lines Qi319 and Ye478 were used as the donor parent and recipient parent, respectively. The CSSLs were selected with 152 equal-distribution polymorphic markers chosen from Maize GDB database and In Del markers designed by whole genome sequencing of Qi319 and Ye478. The CSSLs were constructed with continuous backcrossing, donor segments gradually reduced until there is only a few, hom ozygous donor segments. Characterization of genetic background was detected in CSSLs to analyzed the genome coverage and background recovery. Finally, 134 homozygous CSSLs, which only had a few substitution segments and the substitution segments connected and covered the entire genome, were generated.(2)Eight CSSLs(CL12、CL27、CL34、CL41、CL49、CL51、CL92 and CL115)showed significant different to Ye478 in plant architecture with T test and QTL identification. Among them, the QTL identification of six CSSLs were consistent with the results of genetic dissection with a high-density genetic map on recombinant inbred lines. Three QTLs, CLPH3-1, CLPH3-2 and CLPH6-1, conferring for plant height and two QTL, Cl EH3-1 and Cl EH6-1 for ear height, were located using the stepwise regression by the software QTL Ici Mapping.(3)A QTL related to plant height was identified in the region of Bin 2.07. Height related trait was mapped using the CSSL Z12.The QTL region was mapped between InDel markers myb1930 and myb1968 with the physical distance of 193,054,152Mb~196,872,360 M b. A transcription factor gene Zm MYB31 related to the synthesis of lignin was found in this target region from Maize GDB. The Zm MYB31 was involved in the negative regulation of phenylpropanoids and inhibited to the synthesis of lignin. The over expression Zm MYB31 could lead to dramatically dwarf in transgenic Arabidopsis plants.(4)Primers were designed according to the Zm MYB31 gene sequenc in NCBI, And the target fragment was amplified and sequenced. It shows that the DNA sequence variation which lead to the plant height difference might be in the four locuses in coding regi on and large segment deletion of 5’end. The expression level of Zm MYB31 in Ye478 and Zheng58 in the three leaves stage were significantly higher than that in Qi319 and Chang7-2 using semi-quantitative analysis. It was consistent with previous research results of over expression of Zm MYB31 which lead to dwarf.