穗行数是玉米重要的产量性状之一。本项目以6行自交系组建的连锁群体、大刍草渐渗系群体和玉米关联群体为材料，采用连锁与关联分析相结合的方法，解析玉米穗行数的遗传基础。首先，利用高密度SNP标记构建的Bin遗传图谱，定位玉米穗行数QTL，评价定位QTL的遗传效应和作用方式，并利用近等基因系研究不同QTL/基因的互作效应。同时，在对含500份玉米自交系的关联群体进行多年多点表型鉴定的基础上，利用已开发的50-100万SNP标记开展玉米穗行数的全基因组关联分析，挖掘与玉米穗行数变异关联的位点，剖析玉米穗行数的遗传结构。在以上研究的基础上，精细定位穗行数的主效QTL，利用生物信息学的方法搜索、注释、提取候选基因，最终分离克隆控制玉米穗行数的QTL/基因，进一步采用重测序、表达分析、玉米MU突变体功能互补等手段验证候选基因的功能，挖掘有利等位基因，开发可用于分子育种的功能标记，阐明玉米穗行数的遗传基础。

The ear row number (ERN) is one of the key grain-yield components in maize. In this proposed project, a strategy combining linkage and associated analysis will be employed to dissect the genetic basis of ERN in maize. Through the high-density bin map developed by high throughput SNPs, QTL for ERN will be identified, and their genetic effects will be estimated by using a maize-teosinte introgression population and a recombination population which was derived from a special line with six row numbers. Additionally, a genome-wide association analysis for ERN will be conducted using 0.5-1 million SNPs and multi-environment phenotypic data in a maize association panel consisting of 500 inbred lines. Furthermore, major QTL or genes will be isolated and cloned, which control ERN using map-based cloning. The interaction among the identified QTL for ERN will be further estimated using near iso-genetic lines. Finally, the function of candidate genes, detected in linkage and association analysis, will be further investigated by re-sequencing, expression profiling and complementary test of maize Mu mutant, the favorable alleles associated with ERN will be mined, and function markers will be developed. These research results will provide useful information for understanding the genetic basis of ERN in maize.

玉米是我国最主要的粮食作物，穗行数是玉米产量的重要构成因子之一，解析玉米穗行数建成的遗传基础对于进一步提高玉米产量具有重要意义。本项目分别以6行自交系组建的连锁群体、玉米大刍草渐渗系群体和玉米关联群体为材料，采用连锁与关联分析相结合的方法，定位了17个控制穗行数的QTL，发现少量主效和微效QTL是玉米穗行数建成的重要遗传基础。在此基础上，分别对3个控制穗行数的主效QTL进行精细定位，其中，qKRN2和qKRN4-2被分别精细定位到6.8kb和0.87Mb的区间。通过序列分析发现，编码WD40重复蛋白（KRN2）和SBP转录因子（UB3）分别为qKRN2和qKRN4-2的候选基因。KRN2在玉米雌穗分生组织最高表达，对玉米穗行数的形成起负调控作用。敲除KRN2，玉米雌穗分生组织增大，穗行数显著增多，粒重不变，可提高玉米产量，在玉米产量遗传改良上具有一定的应用潜力。选择驯化分析表明KRN2在玉米驯化过程中受到强烈的选择。互作分析表明KRN2和KRN4-2具有微弱的互作效应。这些研究结果为阐明玉米穗行数建成的遗传学基础奠定了基础，并为玉米产量的遗传改良提供了理论基础和材料支撑。相关结果发表了1篇SCI论文，申请了1项发明专利。培养博士研究生3人。预计本项目获得的上述研究结果将发表SCI论文2-3篇。