玉米骨干亲本及衍生系产量和品质相关基因优异变异的挖掘及育种应用

The foundation parents in maize, which possess some excellent characteristics, such as better comprehensive performance, higher combining ability and broader adaptability et al., have been widely acknowledged playing an vital role in maize breeding. What makes these inbred lines be foundation parents is that there are plenty of elite alleles underlying yield and quality in the maize genome. Detecting and utilizing these elite alleles is very important to the improvement of corn inbred lines. In our project, we plan to use 200 inbred lines as materials, which include five foundation parents, Dan340, Zi330, Mo17, Ye478, and Huangzaosi, and their derived lines, as well as other non-foundation inbred lines. The NimbleGen technology will be applied to acquire the full length sequences of fifty specially selected candidate genes associated with yield and quality of maize. The project objective is to analyze the variation characteristics of these genes in sequence level and to uncover the origin and evolution of these genes in foundation parents and their derived lines. In addition, we plan to find the elite alleles associated with yield and quality characters by using the candidate gene-based association analysis. At last, we will model various mating designs and selection schemes by computer simulation in order to choose the optimal breeding scheme and further to validate it in a real corn breeding program. The results will be helpful to take advantage of these elite alleles in the improvement and innovation of excellent corn inbred lines.

玉米骨干亲本具有综合性状优良、配合力高、适应性广等特点，在玉米育种中发挥了重要作用。这些亲本之所以成为骨干亲本，其基因组中必蕴含丰富的优异等位变异。挖掘和利用这些优异变异，对玉米自交系的定向改良具有重要意义。本研究以丹340、自330、Mo17、掖478和黄早四5个骨干亲本及其衍生系以及其他来源自交系共200份玉米种质为材料，采用NimbleGen技术对前期精心筛选的50个与玉米产量和品质密切相关的候选基因进行定点序列捕获，在序列水平上解析这些基因的变异特征，明确其在骨干亲本及其衍生系中的演变规律。结合产量和品质性状的测定结果，采用候选基因关联分析方法，筛选出优异等位变异及符合玉米高产优质育种目标的最佳基因型。最后采用计算机模拟手段，模拟各种可能的杂交和选择方案，确立最佳育种方案并在育种实践中验证其有效性。研究结果将为利用骨干亲本中的优异变异开展优良自交系的改良与创新提供重要技术支撑。

玉米骨干亲本丹340、自330、Mo17、掖478和黄早四等已在我国玉米育种中发挥了重要作用，这些亲本普遍具有综合性状优良、配合力高、适应性广等特点。挖掘和利用这些骨干亲本中的优异变异，对玉米自交系的定向改良具有重要意义。本研究以这5个骨干亲本及其衍生系以及其他来源玉米自交系共349份种质为材料，采用NimbleGen技术对玉米籽粒淀粉合成途径中的26个品质相关基因以及29个产量性状相关基因进行序列定点捕获，349个样本共获得200Gb的目标序列重测序数据，捕获目标区段全长为459.13kb，每个目标区域平均长度为8.35kb，目标区段平均测序深度均大于100倍。在供试群体的目标区段经重测序共获得16736个SNP，平均每一基因具有304个SNP。结合产量和品质性状的测定结果，采用基于LASSO的多位点关联分析方法，在对淀粉品质性状的关联分析中共检测到34个SNP位点与11个淀粉品质性状显著关联，涉及20个候选基因；5个骨干亲本在33个显著变异位点中均携带相同的等位变异；在显著关联的变异位点中，Mo17共含有18个增效等位变异，其余4个骨干亲本均含有17个增效等位变异。在与产量相关性状的关联分析中，共检测到56个SNP位点与16个产量相关性状显著关联，56个显著SNP涉及29个产量相关的候选基因；5个骨干亲本在40个显著变异位点上携带相同的等位变异；在显著关联的变异位点中，黄早四、Mo17、自330和掖478均含有38个增效等位变异，丹340含有39个增效等位变异。围绕这些产量和品质性状相关的候选基因，采用计算机模拟手段，筛选获得了72份携带较多优异等位基因的玉米种质材料，确定了相关育种组配方案，已提供给项目合作研究单位进行育种应用，初步验证结果表明多数材料具有较好的应用潜力。以上研究结果为利用骨干亲本中的优异变异开展优良自交系的改良与创新提供了重要参考。在该项目的资助下，培养博士后1人，博士研究生2人，硕士研究生3人；发表学术论文14篇，其中SCI论文11篇。