玉米株高主效QTL qPH3.2精细定位及遗传效应分析

Fine Mapping and Genetic Effect Analysis of a Major QTL qPH3.2 Associated with Plant Height in Maize(Zea mays L.)

株高是影响玉米产量的重要因子之一,节间数目和节间长度是导致株高差异的主要因素。本研究发现2个高代回交重组自交系W1和W2株高差异显著(P<0.001),二者穗上部和穗下部节间数目都相同,细胞形态分析发现节间细胞长度是引起二者株高差异的主要原因;外源GA试验结果表明控制株高差异的QTL/基因是GA途径之外的新基因。因此,利用来源于W1和W2的F2及F2:3家系群体在2年3个环境中将控制株高的主效QTL q PH3.2共定位在第3染色体标记C42-P17之间20 Mb范围内,最高可解释22.22%的表型变异。进一步利用目标区段重组交换单株及自交后代家系将q PH3.2分解为2个主效QTL q PH3.2.1和q PH3.2.2;随后利用目标区段的跨叠系将q PH3.2.1和q PH3.2.2分别精细定位在YH305-Y72(2 Mb)及YH112-Y150(1.6 Mb)之间。本研究的结果为玉米株高的遗传改良提供了真实可靠的遗传位点,也为后续株高QTL的克隆奠定了良好的工作基础。

Plant height is one of the most important factors affecting maize yield,which is determined by the number and the length of internode in maize.In this research,two advanced-backcross recombinant inbred lines(W1 and W2)with significant difference in plant height were used.They have the same number of internodes.We found that the different cell lengths of the internode in upper spike were the main reason causing the difference in plant height.The results of exogenous GA test showed that the QTL/genes controlling plant height were not included in GA pathway.The F2 and F2:3 populations derived from W1 and W2 were used to map the QTLs associated with plant height,showing that one major named qPH3.2 was commonly identified under three different environments in two years which was located on chromosome 3 between markers C42 and P17 with 20 Mb and could explain 22.22%of phenotypic variation.On the basis of the primary mapping results,QTL qPH3.2 was divided into two major QTLs qPH3.2.1 and qPH3.2.2 via recombinant exchange individuals and its self-cross progeny.Furthermore,we did the fine mapping work for qPH3.2.1 and qPH3.2.2 using substitution lines.The qPH3.2.1 was fine-mapped to the region of about 2 Mb between markers YH305 and Y72,and qPH3.2.2 was fine-mapped to the region of about 1.6 Mb between markers YH112 and Y150,which all showed the positive additive effects.The results of this research provide reliable genetic loci for the genetic improvement of plant height in maize,and a good foundation for cloning QTLs for plant height in the future.