利用多杂种群体剖析干旱胁迫下玉米杂种优势形成的分子机制

Maize is one of the most important crops, and drought is the main environment factor constraining for the yield and quality. Therefore, the study on maize drought tolerance and heterosis related issues are very important in terms of both theoretical and application implications. A multiple-hybrid population (MHP) consisted of a 1036 MHP F1 hybrids was studied in this project. Basis on previous researches, the drought tolerance traits were identified under drought stress condition. The general combining ability (GCA) and special combining ability (SCA) of the 51 parents of MHP were analyzed, and the related traits gene loci of drought resistance and heterosis were compared and analyzed by using genome-wide association analysis. Differential allele-specific expression and differential gene expression under drought stress were studied by RNA-seq within transcriptome of 3 representative maize inbred lines and their hybrids. Meanwhile, the related genes were analyed by phenome, genome, and transcriptome of hybrid maize to uncover the molecular mechanism for the drought tolerance and heterosis. Our project will not only help to understand the molecular genetic mechanism of drought tolerance and heterosis, but also facilitate shedding light on the whole genome association analysis of maize complex traits.

玉米是重要的粮食作物，而干旱一直是制约玉米产量和质量的一个关键因素，因此开展玉米耐旱性杂种优势研究具有重要的理论和育种学意义。本项目以一个1036份杂种F1代组成的多杂种群体（MHP）为研究材料，在前期研究基础上鉴定干旱胁迫条件下MHP群体耐旱性相关性状；分析MHP群体51份亲本材料的一般配合力和特殊配合力，对相关性状的耐旱性、杂种优势进行全基因组关联分析，挖掘玉米耐旱性杂种优势密切相关的基因位点；以3份代表性玉米自交系及其杂交种进行转录组测序，分析干旱胁迫下材料间等位基因表达量的差异，结合基因组、转录组、表型组对相关基因进行联合分析，为阐释玉米耐旱性杂种优势的分子机理提供理论依据。开展玉米耐旱性杂种优势分析研究，不仅可系统解析杂种优势抗逆性的分子遗传机制，而且为全基因组关联分析玉米复杂性状遗传网络奠定重要理论与技术基础。

在新疆开展玉米耐旱性杂种优势研究，挖掘抗旱性优势基因，阐释玉米耐旱性杂种优势形成遗传学基础，其主要成果包括：以51份遗传背景丰富的温带、热带玉米不完全双列杂交产生了一个多杂种群体，并对亲本采用Maize55K进行了基因型鉴定。依据亲缘关系将51个亲本划分为5个杂种优势群，通过干旱和正常灌水下耐旱性分析，确定了BSSS×NSS、NSS×SPT和BSSS×SPT的为高产、抗逆的优势杂种优势模式；PB群种质形成的杂交种表现出较好的耐旱性，PB种质可作为抗旱性种质用于玉米耐旱性的改良。结合基因型和多杂种群体产量、生育期、株型等表型，全基因组关联分析挖掘到了59个显著性的数量性状（QTL）位点，多杂种群体各目标性状的特殊配合力挖掘到了51个显著性QTL位点。结合前期11个环境多杂种群体表型数据，开展了不同杂交类型杂种优势形成遗传学基础研究，发现上位性效应在玉米温热杂种中起着更重要的作用。本研究采用遗传背景丰富的玉米骨干材料开展玉米杂种优势研究，为优异玉米品种的选育提供了重要的遗传学基础理论支持。